Prism Eyeglasses-Eye Doctors Treatment For Double Vision

Optometrists in Fort Collins Usually Prescribe Prism Eyeglasses For Double Vision

Has your eye doctor prescribed prism eyeglasses for you or your child in a new eyeglass prescription? It could be due to crossed eyes, lazy eye, or some diseases of the eyes or body.

Prisms are thin pieces of the optical material that is used in prescription eyeglasses. You may remember them from high school physics. They have a base that is thicker and an apex that is thinner. Due to the light bending properties of the lens material, the thicker lens base slows light down as it passes through. Since the prism is thicker at the bottom base it slows light down longer than the top apex, and light changes direction down towards the base as it exits the prism. If the lens were equally thick throughout, it would slow the light down but the direction would remain unchanged. The amount of direction change is determined by the index of refraction of the material compared to the index of refraction of air. Lenses with higher indexes of refraction allow optometrists to make the ultra thin lenses that have drastically improved eye comfort and cosmetic appearances in recent years. The light bending capacity of a lens material is referred to as the index of refraction. The value in space in a vacuum is 1.0, essentially the same as in the earth’s atmosphere which is 1.0003.  Eye glass lenses now have indexes of refraction from 1.5 to 1.7, with the higher numbers being the thinnest.

Eyes that cross can turn in or out, and also one eye can turn up or down. Strabismus is the technical term for a turned eye. Eyes that turn out are referred to as exotropic while eyes that turn in are called esotropic. An eye that turns up is hypotropic and one that turns down is hypotropic. These are all considered as cases of strabismus, or eyes that actually do cross. Often they are mistakenly called “Lazy Eyes.”  A lazy eye is a different condition but it may result in a crossed eye. A combination of eyes turning laterally and vertically is common. When this results in double vision, it can be completely disruptive to mobility and lifestyle of the affected person. If the eye turns are present at birth, there may be no double vision present. The brain has the capacity to suppress or turn off the area of vision that results in the eyes perceiving double at early ages. When a person sees double, prisms, eye exercises known as vision therapy, and surgery are the three options eye doctors have to try and restore normal visual functioning. Prisms do not appear as a strange looking triangle in the lens. They usually show up as thicker and thinner edges on the eyeglass lenses. Normally they are ground into the shape of the lenses, but because of optical properties, some lenses can have the optical center repositioned to induce prism. There can be an adjustment to prism added to a prescription while the brain relearns how to interpret the eyes seeing single. When diseases such as strokes and diabetes cause double vision there can be some fluctuation over time, and frequent eyeglass prescriptions changes to adjust the amount of prism may be required. Temporary press on prisms known as Fresnel lenses may be used in some cases when change is expected but their optical quality tends to be very poor.

Your eye  doctor may prescribe prism in your eyeglasses for other reasons

Some people will only have a tendency for an eye to turn, and while it may not actually turn it will result in eyestrain, fatigue with reading, headaches from using your eyes, and other symptoms. These are referred to as heterophorias instead of strabismus. Instead of exotropia your optometrist would call it exophoria. Any term ending in phoria means a tendency to turn while tropia indicates an eye that is turned. To complicate matters, sometimes eyes will cross at one distance and not another, or when viewing in only certain fields of gaze. In cases of traumatic head injuries yoked prisms may be used to help retrain a disrupted visual system by altering spatial perception.

Some serious health problems can cause double vision, and any new onset or increasing condition of double vision should be thoroughly examined by your optometrist

When double vision occurs after the age of fifty, common causes are thyroid conditions, high blood pressure and diabetes. Try to notice when it occurs and what makes it worse to help your optometrist in treating your eye condition with the best methods possible. In the case of a brain tumor inducing double vision, a trip to the eye doctor could save your life.

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129 Responses to “Prism Eyeglasses-Eye Doctors Treatment For Double Vision”

  1. Shereena May 19, 2010 at 5:43 am #

    Dear Doc,
    My father is experiencing double vision because of his brain stem stroke. Can a prism be used, the neuro opth who consulted him said its NOT possible since his number is 20x in right eye and 4x in left.

    Can you please let us if its possible OR surgery is the ONLY option.
    Many thanks,

  2. admin May 21, 2010 at 2:17 pm #

    Hi Shereena,

    Partially it depends on how far out from his stroke he is and whether his eyes turn in or out. The 20 is likely the horizontal component (an eye turn in or out) and the 4 is likely the prism for the vertical eye turn (up or down). There is often a reduction over the first 6 months or so and it becomes manageable just with time. The question to ask is whether the 20 diopters is the actual amount of the eye turn or is it the amount of prism needed. While 20 diopters of prism cannot be incorporated into an eyeglass prescription, 20 diopters of eye turn is another question altogether. If 20 diopters of eye turn is present usually 11/2 to 2/3 that amount is needed. 8 – 12 diopters of prism (which is 4 to 6 in each eye) can usually be done.The 4 diopters is not a problem. Also you need to know if the eye turn is the same in all fields of gaze. It can be more complicated with prism or surgery when it varies a significant amount in different directions of looking. Vision therapy can also help build up fusion reserves to help compensate. Fresnel prisms can be tried over regular lenses temporarily to see if it will help. These are plastic press on lenses, but they do degrade visual acuity somewhat.
    I would find the answers to:
    *Is it is a 20 diopter deviation or 20 diopters of prism needed
    * If it varies from looking in the 8 cardinal directions (up, down , right, left, and the up & right types of combinations
    * Factor in 6 months after the stroke

    Hope this Helps,

  3. Charlotte Jankowiak February 2, 2011 at 2:03 pm #

    My daughter has steroid induced glaucoma. Will prisms help her double vision?

  4. admin February 5, 2011 at 6:46 pm #

    The prism could help with her double vision depending on how much she has. Double vision is usually not caused by steroids. If possible you might ask a few more questions. Is it truly double vision (seeing two of the same object) or more of a halo type of effect from swelling. Is there another medical condition being treated that could have caused the double vision? Often fresnel prisms are applied over the lenses in existing eye glasses to test the possibility of using prisms. These are plastic membranes that adhere to the lens and they can be removed. Optically they do not provide good vision but they do allow testing of prism, especially for larger amounts. Hope this helps and wishing her the best.

  5. Dawn Vincent February 13, 2011 at 2:13 pm #

    My husband recently had intermittent episodes of double vision and was examined by a neurologist. My husband did not have the anitbodies found in ocular myasthenia and was also unable to take the drug used to diagnose/treat that condition due to severe diarrhea. He then consulted an opthalmologist who gave him a press on prism for his left eye. which at first seemed to help so he had more permanent prism made. However, my husband insists that the press on works better, but even that isn’t 100%. Although he passes all of the eye exams, he really doesn’t seem to see things that I see and he sees things that aren’t there….which I guess is a brain function rather than an ocular one. He doesn’t see double when reading, but then he doesn’t read much anymore. He is 69 years old and very concerned about driving.

  6. admin February 18, 2011 at 10:44 am #

    The press on fresnel prisms are often used as a test to see if prism will help. Because the are reasonably inexpensive, I often try stronger amounts than I end up prescribing. I don’t know exactly why but I presume other eye docs do the same thing. So the amount of prism in the lenses could be less. There can also be changes in the amount of prism needed over time which could change the response even though the amount is the same. Fresnel press on prisms deliver poor optical quality to the eyes and the vision is much worse than the permanent prisms. There can be an advantage to the degraded vision if it helps suppress or help the brain ignore the eye that is turning. It is possible that the press on prisms blurred the vision just enough to help him not notice some central double vision while assisting the eyes alignment. The press on prisms may have worked better for some reason but that are not a very good long term solution. Is he nor seeing things as well in general or is he missing things in his peripheral vision? Having gaps in peripheral vision is a much more problematic for driving than a mild reduction in overall vision. If he is passing all of the drivers license requirements maybe a simple refresher course would help boost his confidence. Best wishes.

  7. Dee March 15, 2011 at 10:51 am #

    I am having cataract surgery and my dr told me I could have a special lens put into each eye to clear my vision. I wear Prism lens – can surgery correct this problem?

  8. admin April 1, 2011 at 12:42 pm #

    Hi Dee,

    To my knowledge there are no lens implants that have prescribed prism available. Unfortunately, sometimes the lenses are misaligned and can induce unwanted prism. When prism is induced by misalignment it tends to degrade the optical quality of the image seen, unlike prism that i ground into a lens. To incorporate prism into an IOL it would either have to be inserted into perfect alignment, there is very little tolerance for misplaced vertical prism. Someday there will be a way to add the prism after the lens is stabilized in the eye but that may be quite a few years away.

    Best Wishes

  9. Lexy April 8, 2011 at 3:57 pm #

    I was born with strabismus, and it has been a long time since my eyes see double without me forcing it. However my right eye still turns inward when I am tired, or when I follow something with my vision. I am 25. Is it possible that the prism would help strengthen the muscle. I wear contacts, and sometimes glasses, but I get a lot of headaches still because of one eye being ~ -2.50, the other ~ -1.00. It seems impossible to get the right prescription that will not cause my eyes to strain. Would you recommend I try prism, or am I at a loss? Thank you.

  10. admin April 12, 2011 at 4:58 pm #

    Hi Lexy,

    I would definitely give it a try. Since your eye tends to turn in it is much more likely to help (than if they turned out). Prism generally will not strengthen the muscles but will allow the eyes to stay straight. Actually the muscles are probably much than they need to be, the problems usually are in the feedback to the brain and how the muscles and ligaments are attached to the bones around the eye.

    Best of Luck!

  11. Craig April 26, 2011 at 10:45 am #

    I had emergency retinal detachment surgery in Dec. 2011 and unfortunately it was not reattached properly. I have decent vision in that eye (20/60) but I have slight vertical diplopia and it is slanted slightly to one side. Since the surgery (5 months now) my eye muscles fight to get everything lined up but by the end of the day my eye muscles are sore and my double vision gets worse. Have prism lenses helped in cases like mine?

  12. admin April 26, 2011 at 6:22 pm #

    Hi Craig,

    Prism can help with vertical imbalances. It gets more complicated if it is due to retinal tissue being mis-aligned, since it is still aligned properly in large parts of the eye. There is not a prism that corrects for cyclorotation, or tilts in the image plane. Correcting a vertical imbalance may remove enough stress to allow overcoming this is some cases. You might want to have your eye doc try some fresnel temporary press on prisms to see if it might help. They are not very clear but sometimes will give you an idea of how well it could work. Let me know how it works out.

    Best Wishes

  13. Naomi June 7, 2011 at 5:51 am #

    I have been reading with my left eye closed for quite a few years without conciously realizing it. My eye dr has put temporary prisms on one lens and now both to see if that will help. The stronger prism (5) did not let me drive comfortably except when I closed my left eye. With the new prisms (3) I can drive fine and can read better but looking at the computer is very dificult. My left eye wanders all over and I have been seeing mostly with my right eye. Is it possible to put the prism in the reading portion of the glasses and not in the rest of my no line bifocal. I work answering phones and in between phone calls I read so I need to see both the computer and the book.
    Thanks Naomi

  14. Julie June 12, 2011 at 12:09 pm #

    In March of 2010 my husband had an accident and his bottom eye muscle was detached. We found an eye doctor who was able to reattach the muscle, however he has double vision looking down and to the right. The doctor also did a faden procedure, but it didn’t not completely correct the double vision. He suggested prism glasses, he would like us to find someone in the country who can make these glasses and then he will get in touch with them about my husbands measurements and more specific info. If you are able to help, or can suggest someone who can help us that would be wonderful.


  15. admin June 22, 2011 at 5:59 pm #

    Hi Julie,

    What part of the country are you in?

  16. admin June 22, 2011 at 6:15 pm #

    Hi Naomi,

    I am not aware of any way to do this with a linefree multifocal other than adding a fresnel stick on prism (they degrade the optical quality significantly). It can be done in a lined lens. It might work OK if you had a pair of glasses made with the top set for the computer distance and the bottom set for near. The prism thoughout the lens should be more tolerable than what it is for a full disitance and near Rx. A lens like the “office design” would fit these types of visual demands (but have to be chaged for driving). Hope this option helps.

  17. Worried June 29, 2011 at 1:04 pm #

    Hey, I wear prism glasses, and I have a lazy eye.
    However, I really, REALLY wanna get contacts.
    Can I just get contacts without the prism?
    Is the prism really that necessary?
    My lazy eye is pretty inactive right now. (It started when I was about 5 and now I’m 16)

  18. admin June 30, 2011 at 3:52 pm #

    Hi Annoyed,

    It sounds like you are annoyed with your glasses! Sometimes it works out when you take the prism out for contact lenses. At 16, you are no longer in the critical age period for neuronal development. In other words, you have all the brain cells you are going to get-sort of- well at least in the visual pathway. (There is thinking these days that the frontal lobes of the brain don’t fully develop until the mid twenties which is probably why a lot of people over the age of 30 think anyone under the age of 20 has no brain:) If you don’t help that eye see its best by age 7 to 9 it is very hard (if not impossible in many cases) to generate the part of the brain you need to see 20/20. So you are probably OK to try contacts without the prism. There is no guarantee the lazy eye won’t backslide and get worse but resuming wear of the prisms will usually fix that fairly easy if it happens. Best of Luck.

  19. John July 2, 2011 at 6:04 pm #

    Hello Admin,

    I have a quick question regarding Prisms. My eyes are normal/straight in everything I do…;however, when I look at something up close 1-3 inches (bad) 3-5 inches (moderate) 5-7 (less) I get double vision.

    Now it’s bad since I don’t never looked at things closely…; however, I recently got into dental school and I have to stare at small objects in close proximity for hours a day. 4-10 hours. Eventually my eye gives out from straining, and I go double vision from 1-7+ inches. My right eye also turns upwards which means I do have slight strabismis.

    I went to the Optometrist and they corrected it with prisms, and its a WORLD of difference. However, I’m worried…will the extended use 8+ hours a day results in PERMANENT strabismus? I understand that prisms reflect the light/image into affected eye results in singular vision…but if I strain it in that direction for extended periods of time…will my strabismus actually get worse? For example when I look normally- I’m currently normal…but with the extended use…will I actually develop strabismus when I am NOT doing dentistry and just doing normal everyday activities.

    If so…I might actually drop out of dental school…I’m really worried. I have nothing against the condition, and I love my prisms…but if it makes it permanent when I’m looking at things afar…I might reconsider my profession all together….

    Thanks Admin

    Concerned patient.

  20. admin July 2, 2011 at 8:20 pm #

    Hi Currently Normal John:)

    Usually prisms are prescribed based on the viewing distance that has the lowest amount of measured tendency for the eyes to turn. In your case that is probably at 20 feet or more. That allows patients to not have eyestrain created by unneeded prism. If eyes tend to turn in a bifocal can also be used, allowing for more compensation at near.
    For eyes that turn in there is usually no long term adaptation to prism. For eyes that turn in there can be long term adaptation. Long term adaptation does not make problems permanent, it only means the amount keeps needing to be increased to get the desired effect. If you don’t wear the prism, things should return to their initial state fairly rapidly. If your eyes turn in causing double vision (or up or down), prism will likely just make things better. If they turn out, extended near work combined with the fatigue of studying hours on end will could result in things getting a little worse, especially when you are tired at the end of the day. The prism will not cause anything to become permanent, but the strain of working up close all the time could cause more frequent double vision but I do not believe there is any evidence that prism or close work causes permanent double vision. I’m sure there are people who would claim that had happened, but some people will develop permanent double vision coincidentally with changes in near work (that would have occurred regardless of what they were doing). That being said, go to dental school if that is what you want to. If the prisms don’t give you enough help over time you can always do a course of vision therapy. The eye exercises work best for eyes that tend to turn out anyway. Therapy also works better for people who only have a problem at one viewing range (in your case very close).

    Stereopsis 3d vision is helpful for dentistry, especially for the type of things endodontists do. Check to see if you have it with the prism correction. You can still do dentistry without it. There are loupes or magnifying aides that can be used over one eye only that eliminate the eyestrain issue altogether. Magnifying scopes over both eyes often have prism built in to help. Extended viewing at 1 to 7 inches is not a normal visual task and creates problems for a lot of people. I think its great you are thinking about these things now.

    Best of Luck!

  21. Veronica July 29, 2011 at 6:22 pm #

    Hi, Admin,
    I have double vision caused by multiple sclerosis – a lesion on my brainstem. It has gotten worse over the past few years. It used to in my peripheral vision only, but now it’s in my entire field of vision. I had a test (can’t recall its name, but it measured signal speed from the brain to each eye and involved looking at a monitor with wires hooked to my scalp) that showed the brain sends signals to each eye at different speeds. The good news is my brain often compensates for my double vision – but not always, especially if I’m tired, hot or trying to to change my focus frequently. (I can’t look from the TV across the room to knitting in my lap, for example. My question: since my double vision seems to change, would prisms be an option? Thanks very much.

  22. admin July 30, 2011 at 7:48 pm #

    Hi Veronica,

    You probably had a VEP or Visually Evoked Potential Test that measure the difference in nerve conduction speed in the optic nerves of each eye. Ms can cause double vision from damage to the myelin 6th cranial nerve that helps eye turn out or from damage to the nerve sheath of the medial longitudinal fasciculus (MLF) in the brainstem. The MLF is just a little too complicated for me to remember; it carries a bunch of different information up and down from the brain. Some of these nerve pathways carry visual information to the eye muscles on how to work together. Sometimes MS damages these tracts and results in Internuclear ophthalmoplegia (INO). INO creates double vision when you try to look to one side due to the inability of the effected eye to turn towards the nose. The other eye turns out normally but has nystagmus (or shakes). This only occurs when both eyes are looking in the same lateral direction, not when you look at something up close for reading.

    That being said, it is very difficult to answer your question due to the intermittent nature of MS. Prism could help if you had a bad stretch where it was really bothering you an due to a 6th nerve palsy. If it is due to INO yoked prism might help also, and while it is a little strange at first, you might be able to leave it in the prescription even it was coming and going. Yoked prisms allow you to see to one side without turning your eyes as much. Other options can include a small central occluder (or dark spot) in the central area of glasses or contact lenses (on one eye only). This can reduce the incidence of double vision without effecting peripheral vision when it is problematic. In a contact lens it appears like the normal pupil. You can also under correct the problem eye to blur it up enough to help the brain overcome the diplopia.

    I have seen a few people go from severe MS to complete remission (long term). Who knows why but I hope you fall into that category and never need any of the above information!

    Best Wishes

  23. janet August 25, 2011 at 10:09 pm #

    I was prescribed prism glasses. My eye will often “stick” and then I suddenly have double vision, up and down images, in both eyes. If I close one eye, either eye, it goes away. I had Graves disease which was treated with radioactive iodine about ten years ago. My question is, am I supposed to wear the prism glasses all the time? or should I use them only when tired? or when driving, which obviously can be dangerous when the eye turns and “sticks,” which seems to happen when I am looking for other vehicles to make a lane change or turn.

  24. admin September 6, 2011 at 4:49 pm #

    Hi Janet,
    They really should have told you when to wear the glasses when you got them:) It sounds like you could benefit from wearing them all the time if you are having intermittent double vision-not the best thing to have when you are driving down the highway at 70 mph! The thyroid treatment helps treat the thyroid problem but does not necessarily correlate with the eye problems of Graves disease. The muscles that move the eye can become swollen and restrict movement, which results in double vision. If you pay close attention you will probably find it tends to happen when you look in certain directions. The most important thing you can do to prevent progression of this condition is to stop smoking (if you do). Occasionally the double vision goes away over time – I hope that happens to you!

    Best Wishes

  25. Chris October 12, 2011 at 7:25 pm #


    I recently received a prism in my eye glasses because my eye doctor diagnosed with me with a lazy eye and I was feeling discomfort in my right eye for quite sometime. He also recommended the prism because sometimes I can see slightly double. Now after having these new glasses for about 48 hours the prism doesn’t seem to be working since I still feel straining in my right eye. What could / should I do? I contacted the doctor and he said to get back to me in a MONTH and tell me if it still hurts then. I have a very strong prescription and can’t function without my glasses, I’m clueless in what to do.

    Thanks For Your Help!


  26. admin October 23, 2011 at 9:39 pm #

    Hi Chris,

    I presume the lazy eye was turning out or in at times (or has a tendency to turn that was causing eyestrain). 48 hours is not long to adapt to prism, sometimes it does take a few weeks. If the double vision is gone or significantly lessened you are headed in the correct direction. Eyestrain might take a while to go away or the prescription may need to be adjusted at some point in the future. If you are having resolution of double vision hang in there a few weeks it will probably get better. If you still have double vision call & tell them you need to get in sooner and if not possible get a second opinion. To me, double vision can be dangerous when driving or working and needs to be addressed, even if there is a period of discomfort while adjusting to the prism.

    Best Wishes

  27. Tammy October 24, 2011 at 1:16 pm #

    I have worn prisms in my glasses for about 20 years. I am having trouble with my eyes now. I am seeing a shadow on things. The shadow goes right and down. At night, in light or dark, when I am tired my vision goes completely double. I can pull the image back to the shadowed image by blinking hard. The shadowed images are easier to see when looking at letters or numbers. The shadowed images are not a glow it is like the image is trying to double. It seems to me that the image is a doubled outline or what I am looking at. I am having a lot of trouble with helping my eye doctor to help me. She doesn’t seem to want to deal with the problem. My prisms are 5up and 5down. Is this a lot of prism? Will more prism help me or am I just going to have to live with this or get help in some other way? I hope there is something that I can do because seeing signs to drive is becoming all most impossible. How can I help my eye doctor help me?



  28. admin October 24, 2011 at 2:50 pm #

    Hi Tammy,

    You do have a large amount of prism. Sometimes it is hard to distinguish double vision symptoms from blurred vision. It helps if you close one eye-the symptoms should go away if it is from double vision. I would write down something for your doc just like you did here and take it in with you. If you are having diplopia or symptoms related to a breakdown in binocular vision the prism should be able to be adjusted to compensate. On occasion some vision therapy or eye exercises can also be used to help the eyes work together. Try again but if you can’t get help look for a second opinion.

    Best Wishes

  29. Jen October 24, 2011 at 6:26 pm #

    HI, I was recently prescribed prism glasses for a strabismus. The md suggested I wear them for 2 months to see if it would help. I currently do not wear any glasses and my vision is fine. My main question that I did not ask md was if i wear them for 2 months, will my eyes get used to wearing glasses and will i get stuck with glasses even if it does not help correct condition? Or, will i be able to take the glasses off and go back to “normal”? Basically, is there a big risk in trying this?

  30. admin October 25, 2011 at 5:02 pm #

    Hi Jen,

    There is a risk for everything but not so much with your situation. If you are seeing double at times the prism can help (and it is kind of risky driving and doing other things like using power tools when you have to decide which one is real!). Some people may adapt to prism over time but if you stop wearing them normally things return to the state they were originally in. The only significant risk theoretically could be for someone who is suffering from eyestrain without double vision. It could be possible to develop double vision if the prisms allowed for some suppression of vision in one eye to lessen and the prism was not adequate for keeping the eyes aligned. That being said, I have never heard of any cases of this from simply wearing prism. I don’t really think there is a downside or risk other than it not working and spending a little money. I would not hesitate to try it, the upside is clear, single, comfortable vision. Keep in mind that strabismus can change over time completely unrelated to wearing or not wearing corrective lenses or prism.

    Best Wishes

  31. Jessa November 15, 2011 at 10:58 am #

    My daughter went for her for her annual eye exam, last year needing reading glasses +.75 this year he says it’s the same but needing prisim??? The info I have found it seems she would need the prisim all the time not just for reading. Unfortunately this eye office is rude and doesn’t want to waste time answering questions, but is the only office that my insurance covers. So my question is about prisim’s and reading glasses.

  32. admin November 15, 2011 at 4:24 pm #

    Hi Jessa,

    I don’t know why your eye doctor prescribed the glasses but frequently kids have eyestrain from esophoria (or a tendency for the eyes to turn in) when using their near vision. The eyes involuntary turn in when we focus for near objects. This relationship (or synkenesis) between accommodation and convergence can be treated with glasses if it is abnormal. Plus power lenses relieve the eye of some of the focusing and thus also reduce the amount of esophoria at near. Sometimes the lenses alone are not enough and prism must also be added to the prescription.

    A similar problem but on a much smaller scale is a “fixation disparity”. This is a very small eye alignment error that can also be associated with focusing for near objects. Since the eye does not have to alter the lens shape to focus for distance (except in hyperopia i.e. farsightedness), both of these conditions typically only need treatment for reading and close vision.

    It might be worth your while to check on the added cost of seeing someone out of network if you are not happy with your current options.

    Best Wishes

  33. DJ November 15, 2011 at 6:21 pm #

    Hi Admin:

    I’ve worn prisms for over 40 years. Recently I was prescribed high blood pressure medicine. Can it increase problems that prisms are supposed to correct like double vision. I noticed it is worse when it’s bright out, not too noticeable at nighttime. I’m scheduled for a eye checkup in a few weeks. Thx

  34. admin November 15, 2011 at 8:26 pm #

    Hi DJ,

    Blood pressure medications can cause double vision but that is unlikely. High blood pressure is a fairly common cause of double vision and you could have created a problem that was not related to the start of the medication. Fortunately this type of double vision usually resolves without treatment within 6 months or so. Most likely would be a breakdown of how your eyes are working together just from time. You may only need a tweak in your prescription to set you back on the right track. You are taking the right step in seeking professional eye care to determine the cause. Just keep in mind that the consequences of untreated hypertension are devastating and if it does happen to be a rare case related to the medication persist in getting it changed to something else that works better. So many people just stop treatment when faced with side effects thinking there are no other options-there always are!

    Best Wishes

  35. RG December 11, 2011 at 11:47 am #

    Hi Doc,

    I had gone through Lasik surgery(Epi-lasik), initially everything was ok but later i felt stress on my eyes and finally i found out that my right eye vision is degrading gradually. Actually it had developed double vision. Due to which i got severe headaches. I consulted doc who operated me. He tried different medicines, Exercises but no good results, After that he decided to operates it again to remove any abrasions left on the eye. again after three months as it takes that much time after Epi lasik for an eye to get normal, double vision reoccurred in my right eye. Again doctor tried some medicines like pilocarpine to make eyes muscle contract to make single vision, it worked 60 to 70% but as soon as i leave it problem reoccurs and worse than before. I have stopped visiting the doc for few months. As m not finding any anything good visiting him. During work, sometimes I feel severe pain like my eyes specially the right one is gonna come out and also its feels like my right eye is becoming less responsive when i try to focus any object. Doc can you suggest me what should i do, If i visit some other doctor and if he says that i need to get operate again, should i go for it or not as my right eye has already got operated two times. Is it safe to get operated that many times?…Please help……

    Thanks and regards,

  36. admin December 21, 2011 at 10:04 pm #

    Hi RG,

    It sounds like you have had a tough time. The outcome of additional surgery is not as good at this point for most patients. I would recommend you see someone who specializes in treating dry eyes and contact lenses. There are a number of options available in contact lenses today to help correct the irregularities that can occur after refractive surgery. These irregularities are the normal cause of double vision. Dry eye after LASIK is the most common cause of discomfort after surgery. Occasionally the cornea will have recurring abrasions in the morning after awakening and these can be quite painful. You might want to notice if the discomfort is worse in the early morning or mare as the day wears on. Dry eye syndrome
    usually is worse towards the end of the day.

    Best Wishes

  37. JJCIII December 23, 2011 at 1:23 pm #

    I have had prism added to my glass lenses for about five years. Recently ,I purchased new glasses because of changes in my right eye. The new glasses are causing double vision when reading. To correct the problem I have been ujsing a bookmark under the lines in a book to stabalize my vision which helps to some extent but obviously an unsatisfactory solution.

    I returned to the glass shop and the optician examined the glasses and said that the prescription had been filled correctly and suggested that I return to the doctor for a re-exam.

    Is the a common occurance? It has never happened to me before.

  38. Craig December 26, 2011 at 8:30 am #


    My mother was recently diagnosed with Graves disease. She is having a lot of problems with double vision and her doctor wants to try prism glasses. Any thoughts on this?


  39. Peggy December 31, 2011 at 12:04 pm #

    First, thanks for helping all of us! Yesterday I went to get my eyes checked and, when he did the tell me when the lines match up test, the one on the left side would disappear from sometimes. He told me I had a floating eye. It occurred to me that I sometimes see double, typically when I am focusing on one thing. There doesn’t seem to be any difference in distances. He asked me when the double vision started but I really can’t remember. 3 years ago an idiot pulled into my lane on Thanksgiving and hit my car head on with both of us going 70. I woke up after a month of being in a medically induced to the news that my Mom had died and been buried a couple of weeks before…Merry Christmas! As you can imagine, between the mental issues of dealing with sleeping through a month when the most important in your life died, as well as the huge physical hurtles I would spent 3 months in the hospital/rehab trying to get to a point I could at least survive at home, a little double vision here and there wasn’t a huge priority. As one of the people above, when I sometimes close my left eye but not sure why. Ok, 4 pages later, when I told him I had been in an accident he said that must have damaged a nerve. As far as I know, I had no head trauma, I was awake from the moment we collided until they knocked me out in the helicopter. I did fill out a sheet to see if I could remember random things and had no problems. I was fine with his answer until I googled double vision and found that there are tons of things that can cause it. He didn’t give me disposable prisms just wrote me a prescription with it added. I am 45, have worn glasses most of my life, was given my first bifocals just over a year ago. Since my eye tests haven’t shown this issue before and it seems like my current glasses have made a sharp decline in clarity over the last few months, is it probable that this is something from the wreck after 3 years? Should I go see my primary care dr? Another type of dr? He didn’t seem to want to give me any answers as to is this permanent? Going to get worse? He just said with head trauma you never knew but that pot smokers destroy their optic nerves…I really appreciated knowing that when I have smoked it once in my life and look more suburban mom than pot smoker! Help! Happy New Years and thanks again for all the help!

  40. admin January 3, 2012 at 7:22 pm #

    Hi Peggy,

    So sorry about your accident, I hope 2012 turns out to be much better. It is miraculous just to survive that type of impact. I would think the double vision probably is a result of the accident and some unknown trauma to the head or neck, but you should have a routine work up with your family doc to make sure there are not any other problems that have caused the problem, especially if it is getting worse. There are people who specialize in neuro-optometry and optometric rehabilitation and I would recommend seeing one if the new prescription is not solving your problems. Unless there are other health issues, it will probably not get worse. Double vision from diabetes is one of the cases where it normally goes away over a period of months. Some cases can be helped with eye exercises, but if prism resolves the problem that is the normal method of treatment. If your vision is getting worse at reading and near work, that is an expected change. Even though it changes gradually in your 40’s, when it bumps into distance you work at it seem like it changes overnight. Distance vision normally does not seem to change nearly as fast at this age. If you are experiencing rapid changes in your distance vision it still is probably normal, but should be looked at more carefully.

    It sounds like your eye dr was the one who had been smoking pot. Marijuana does not destroy the optic nerve and may provide a minor amount of protection against nerve damage from glaucoma. It is not very practical to have people use it every two hours plus there are a few side effects (like intoxication and forgetting to use it every 2 hours). If you smoked it once I cannot even remotely imagine how someone could imply that it could effect your eye sight. I think maybe he did inhale.

    Best Wishes

  41. Richard Hughes January 12, 2012 at 9:46 am #

    If I site in a handgun that I shoot with one eye closed when I have an eyeglass prescription with a prism of 1 and my prescription changes to a prism of 2 will I need to sight in the handgun again?
    In other words, will now not be looking where I was before and the gun not be shooting where I am looking?

    Thank you,


  42. admin January 13, 2012 at 7:21 pm #

    Hi Richard,

    Normally prism only effects your vision when both eyes are open. It does move things a little in space with one eye open but the adaptation to that effect will be over before the second shot leave the barrel. The adaptation with both eyes is more a matter of how both eyes work together and can take some time. Even with both eyes open you tend to shut down one eye when you focus in on the front sight. It should not be a problem. I would presume with 2 it is probably a vertical alignment issue. If all else fails aim for the top target (and away from me)!

    Best Wishes

  43. admin January 13, 2012 at 8:28 pm #

    Hi JJ,

    Prism can be a little difficult, and when your prescription changes sometimes it effectively alters the total amount of prism in the glasses, even thought the prescribes amount of prism stays the same. Have your beye doctor recheck your eyes, they should be happy to make sure everything is the best it can be.]

    Best Wishes

  44. admin January 13, 2012 at 8:33 pm #

    Hi Craig,

    It sounds like a good idea to me. Graves disease can create swelling in the eye muscles that control how the eyes work together and prism can compensate for this. If her vision starts to decrease you do want to have XRays or an MRI of the eyes to make sure the swelling is not effecting the optic nerve. Compression of the nerve can lead to blindness if not treated.

    Best Wishes

  45. Melissa January 23, 2012 at 2:23 am #


    I was currently received a new prescription of OD: Pl with Prism 2B0 and OS: -.25 with no prism. I got and they are for wearing all the time. (Up until this new prescription i only had to wear them while i was reading for double vision, but because of my left eye deteriorating a bit he would like me to wear them all the time). I had the prescription filled and the glasses are working just fine. But I would like to get a few additional pairs of glasses filled, and was wondering if I could leave the prism out of it?!? and if it would make much of a difference, as for the double vision only occurs while reading.

    I am 25, and had corrective eye surgery when i was 7 to straighten the the turn in my right eye. As for vision in that eye, according to my dr. i don’t really use it, as its so distorted, and my brain just has my Left eye over power it. (but it kicks in while reading and i get the double hazy vision).

    So am I able to get some additional glasses with out the prism for when i’m out and about, and just make sure i use my glasses with the prism when i’m reading/at the computer?


  46. cc January 28, 2012 at 8:53 pm #

    I am 34 yo and for the past mo had proptosis (where eye looks to be bulging), this caused my eyes to look asymmetrical. My pcp did labs, (thyroid, sugar, cholestoral), all were norm. He did say I had bad inflam in my sinuses and thats the culprit to my proptosis. Now my swelling is going down but the when I saw the eye dr. (after i saw my pcp) he said I had and eye turn and that its just more pronounced with my proptosis. now he thinks i might need a prism in my glasses. I was just wondering if my eye will begin to rely on the prism to see straight? do prisms help with an eye that turns slightly up? thanks much for your help.

  47. brendan gallagher January 29, 2012 at 4:19 pm #

    Dear Sir/Madam

    My question is how many prisms can one have in your lenses. I have 4 in my left lense and 2 in my right lense

    Kind Regards

  48. Liesel Meier January 30, 2012 at 5:32 am #

    I had buckle surgery for detached retina (no gas bubble) four weeks ago. I still have extreme double vision; especially when looking straight or up. Looking down seems better. Still in a lot of pain, as well as headaches. The surgery eye does not seem to follow the good eye as far as the muscle is concerned. Eye doctor says he might have to do another surgery to snip the muscle. I do not think I could physically and psychologically do another surgery. I am 72 yrs. old. He will in the meantime send me to have prism glasses fitted.
    Should I first just try the glasses or should I go for a second opinion?

  49. Peggy February 1, 2012 at 2:04 pm #

    Hello, admin,

    I was prescribed prism lenses a few months ago to try to cope with chronic nystagmus I have as a result of Meniere’s Disease that was treated with surgery last year (labyrinthectomy). For the first month I felt OK with the new glasses, after an initial week or so of very strange feelings of dizziness. It became better going into the second month, but very recently I’ve felt more eye strain and discomfort, as well as slightly blurred vision.

    I’m wondering why I’m not fully accustomed to the lenses at this point, and whether I need to go back to the ophthalmologist. I still feel dizzy every day, too, which was the symptom we hoped the prism lenses would make go away. The prism prescription is very mild, and only on the right lens. My glasses are progressives, with a mild magnification for distance and somewhat stronger magnification for reading.

    Any advice or comments would be greatly appreciated.

  50. admin February 1, 2012 at 8:41 pm #

    Hi Peggy,

    Meniere’s Disease must be rally tough to cope with the dizziness, you have my respect. When the base input from the ears to the brain is imbalanced from asymmetric damage in the ears, jerk nystagmus results. If there is a null zone, or area of gaze where the nystagmus is lessened, prism can be used to keep the eyes turned towards that field of view without turning the head. I presume that is why the prism was prescribed, but usually that would be in the form of “yoked prism”, which entails prism in front of each eye. It is possible there was a small amount of prism placed in your prescription for a vertical eye imbalance that predated the Meniere’s. In that case your eye doc was trying to improve the way your eyes work together overall to try and help them compensate for the nystagmus.

    It is normal to have some fluctuation in the nystagmus just like the overall disease. The brain also tends to dampen nystagmus over the course of the first month. Either way (or both combined) it would not be surprising to adapt at first and then have some changes like you have described. Prism can be a very odd thing for the brain and leave funny feelings in your head for a day or so if it is not matched up to what you need. Spatial shifts are induced in the brain and the brain has to reset so to speak.

    I would go back and have it rechecked. There are also some optometrists that specialize in neuro-optometric rehabilitation. Sometimes sensitivity to nystagmus can be reduced through vision therapy procedures.

    Best Wishes

  51. admin February 1, 2012 at 8:59 pm #

    Hi Brendan,

    The amount of prism that can be ground into a lens is determined by the frame size, shape, and the amount of prescription in the lenses. Too much prism will not allow the lens to stay in the frame, and the distortion induced by the prism may become excessive. That being said, 5-6 in each eye is probably the upper limit of what is practical. Fresnel press on prism can extend this range but they do significantly reduce the clarity of vision. People that are partially sighted can tolerate higher amounts of prism in specially ground lenses since the distortion of vision form the prism will not be as noticeable. Hope that helps.

    Best Wishes

  52. admin February 1, 2012 at 9:07 pm #

    Hi Melissa,

    Normally with prism being used Base Out it would be used in front of each eye. Are you sure there is not some vertical prism base up or base down in the glasses? If it is just in front of one eye I would think you should be fine without it at those times but you would need to ask your eye doc for an Rx without it.

    Best Wishes

  53. Peggy February 2, 2012 at 8:47 am #

    Thanks for your reply, that all makes sense. When you talk about vision therapy, could that be the same type of exercises I used to do when I was undergoing vestibular rehab therapy? I would toss objects and follow them with my eyes, read a chart that had letters all over the place, and turn my head back and forth while keeping my eyes focused on an object in front of me. Sound familiar? If those are what you’re talking about, I can go back to doing those exercises at home, or get my ENT to prescribe more formal VRT. If those aren’t what you meant by vision therapy, would you please explain what this is and how I could get some?

    Thank you again. I’m glad I found this site. (Funny detail: I lived in Colorado for eight years but am now back on the East Coast.)

  54. admin February 6, 2012 at 9:05 pm #

    Hi Peggy,

    That is pretty close to what I mean. One of the things that I feel is important is adding motion to the activities. By that I mean after tracking objects you track with your head in motions like you described, then move on to tracking and focusing with your body in motion, then adding the challenge of varying postural balancing while doing the above. Beyond that other perceptual strains (like noise and mental processes like math) are added to overload the system. When you can deal with high levels of sensory input and function well you can usually overcome the symptoms. You may see it referred to as visually-related motion sickness, See Sick Syndrome(SSS), or Neuro-Ocular-Vestibular Dysfunction and a few other names.

    Best Wishes!

  55. admin February 6, 2012 at 9:11 pm #

    Hi Liesal,

    You are still pretty early in the process so give it some more time to improve. I would try the prisms knowing it could still change over time. Second opinions are always a good idea but it will probably take a little while to get an appointment. If things get better in the meantime you can always cancel the appointment.

    Best Wishes

  56. admin February 6, 2012 at 9:15 pm #

    Hi cc,

    With vertical prism there is not normally adaptation over time so its not much of a concern. Some other types of prism may have adaptation and prove less effective as it is worn. Vertical eye turns usually require smaller amounts of prism. You might notice double;e vision more frequently when you don’t wear the prism but that is usually moire awareness and not more reliance on their prism.

    Best Wishes

  57. Peggy February 10, 2012 at 7:21 am #

    This is great… I really think I might be on the right track for something that could help me now.

    Could you tell me what kind of specialist I should be looking for to help me with this? Am I looking for an ophthalmologist who specializes in this, or a neurologist, or a physical therapist? Where can I start looking for an expert to guide me through this? I’m on the East Coast, so unfortunately I can’t come in to your office. :(

    Thank you so much for the new clues. I think pursuing this could really help me improve my balance beyond where I am now.

  58. F.D. March 5, 2012 at 3:44 pm #

    I’m wondering, is any downside to prism eyeglasses? I sometimes see double when looking at faraway objects, but not always. My optometrist gave me an eyeglass prescription with a new prism component, which fixed the problem (at least, when looking at the eye chart). But if I get new glasses with the prism component, will my eye muscles get complacent and weaker? Or will my eye muscles be healthier, or no effect?

  59. admin March 16, 2012 at 7:24 pm #

    Hi F.D.,

    There was a saying when I was in school that went something like this “Base In is a Sin, Base Out without a doubt. Base out prism is used for eyes that turn out (exotropia) ans base in for eyes that turn in (esotropia). There is not a problem when it is used either way. For eyes that have a tendency to turn out or only turn occasionally there can be adaptation to the prism requiring increasing amounts over time. It is not permanent, if you quit wearing the prism it will normally return to its former state. It’s a “sin” to use the prism in many cases like this because it does not do any good over the long term. The eye muscles are about 100x stronger than required to maintain eye alignment. Prisms have no effect one way or the other on their strength or health. Eyes turn due to inadequate nerve impulses, faulty insertions or faulty tendons. When all is said and done, prisms are worth trying in most cases of eye turns but they may not always work.

    Best Wishes

  60. KARAN RAVAL March 21, 2012 at 3:59 am #

    Hi Sir,

    i am an optometrist from India,now i have a case where a patient of mine is having congenital nystagmus ,his rx consist of OD: -2.75/-1.75 X 10 OS: -0.75/-3.0 X 175 , now the problem is that he has null position in the dextroversion and needs to do bit chin down in order to dampen and to read with proper clarity in both distance and near, Can you suugest what should be done in this as i have found prism of 13 bi in OD @ 30 and 10 BO@160 so as to bring his null postion in primary gaze,therefore kindly suggest or advice as what next should be done…… .the patient is wearing contact lenses in both the eyes and is aged 22 yrs.

    looking forward for your valuable suggestion…

    karan raval

  61. Anna March 29, 2012 at 8:45 am #

    I’ve had brain surgery about 6months ago and as a result I am suffering from double vision. I had prism glasses made to correct it. I have two questions a) do contact lenses exist for such a problem b) are there any exercises I can do to help reduce or eliminate the problem of double vision please? Thanks for your help

  62. admin April 3, 2012 at 7:41 pm #

    Hi Anna,

    Some contact lenses with certain type of prescriptions can incorporate small amounts of vertical prism but not horizontal. It usually is not enough to resolve issues like yours, but in the right cases can help a little. Vision therapy type of eye exercises can help many cases. Prism in glasses is the easiest and least time consuming approach. There can be other benefits from vision therapy for patients who have had head injuries or brain surgery. You might want to talk to an optometrist in your area who does neuro-optometric rehabilitation.

    Best Wishes

  63. admin April 3, 2012 at 8:03 pm #

    Hi Karan,

    A lot of people seem to be having success with mini scleral rigid gas permeable contact lenses in dampening congenital nystagmus. I have only tried it with one patient so far using a 16.5mm diameter lens.
    It seems to work very well in some patients. I hope that is some help if you have not tried it yey.

    Best Wishes

  64. Michael April 11, 2012 at 6:15 pm #

    I am having problems with pain on one side of my head. My doctors are currently looking into this, but I saw my optometrist today and he told me to make sure my doctor knows that I have Prism glasses, that it may be relevant. He was very busy so I could not talk to him. What did he mean? Do you know? What should I be telling my doctors about?



  65. admin April 25, 2012 at 2:36 pm #

    Hi Michael,

    One sided pain is always a worry. You eye doctor must have found an imbalance in how your eyes were working together. Prism can help neutralize that imbalance and relieve stress in the visual system. If that does not help there are a number of other conditions that can create pain on one side of the head. Temporal arteritis tends to cause head pain, scalp tenderness, and pain when chewing. Blood tests can detect this a similar diseases. Tumors in the brain can be detected by imaging with MRI’s. Migraines headaches are also common although they usually are not localized to one side all of the time. Prism in glasses are a very inexpensive way to rule out eye muscle imbalances as the cause (compared to most other forms of testing). If you don’t get quick resolution ask for a referral to see a neuroloigist.

    Best Wishes

  66. admin April 25, 2012 at 2:39 pm #

    Also- keep a record of when they occur, where they are, how long they last, if anything makes them better or worse, is it only during the week or on the weekend also. Any other symptoms that may also be occurring. It also can help to know how bad they are on a scale od one to ten. Keep a log and discuss it with your doctor. After you get the new glasses you will quickly be able to tell if they are helping.

  67. Suzanne April 28, 2012 at 3:35 am #

    Hi I have for years wore eyeglasses with prism, but I have notices an increase in double vision. I had my eyes rechecked and found out my prism went up from April 2011 at a 1,October 2011 up to an 8 and now April 2012 up to a 20 prism. I have not been diagnosed with any major medical problem. I had eye muscle surgery in 2005. At the time of surgery I had a 13 prism. Is this possibly more than needing eye muscle surgery? The rapid increase is unusual this time.

  68. malcolm horsley May 1, 2012 at 3:53 am #

    i started to have blurred vision/double vision tuesday last week . tests have been done and a muscle ombalance have been found. i have been using a pair of prescribed glasses with a prism in the left lens. i need to get back to work soon but although i can adjust to the glasses sitting down , when i move my head or walk about i start to feel nausious and i cant see this improving . do you think this will improve if i persevier please ?

  69. admin May 5, 2012 at 1:28 pm #

    Hi Malcolm,

    Do you know the cause of the muscle imbalance? While a primary cause is not always found it does have bearing on how well you will adapt over time. In most cases the symptoms you are describing will decrease and you will adapt to the prism. If there is an underlying systemic problem like thyroid disease the muscle imbalance could change over time making adaptation more difficult. The majority of people never show a specific cause and adaptation occurs over several weeks to several months.

    Best Wishes

  70. Lupércio Hernandez May 12, 2012 at 2:16 pm #

    I am looking for a glaucoma glasses to allow a cousin of mine to play football or others sports.
    As he lost the peripheriferal vision its very difficult for him to play some sports.
    If tyou don’t have the right glasses could you inform were can I find it?
    Would be necessary a doctor prescription to find the correct glasses?
    thank you

  71. admin May 15, 2012 at 8:22 pm #

    Hi Lucercio,

    The first question is does he have a loss of peripheral vision that encircles a central zone, or is it a loss of one side in each eye.

    For circular losses he can uses lenses that have a vertical strip of prism placed toward the out side edge of each lens. Then when you look to a side one eye will have expansion of the field of vision while the other will still be viewing through a normal part of the lens. This can work fairly well if the vision field covers about 100+ degrees. For larger areas of peripheral vision loss he may need to use a tubular type of field expansion system. This entails either surrounding a normal central area with prisms that are focused in different directions so the field can be expanded not only to the sides but also up or down. Small round segment areas can also be added to the side of each lens. When these are viewed through they serve to minify what is seen. Since things are smaller they also have a larger field of view and expand peripheral vision.

    For vision losses to the side there are two systems that are frequently used, The Goettlib System and the Peli system. For people who have lost vision from strokes or certain types of head/eye injuries these can expand (and sometimes help treat) losses of side vision.

    Many of these type of systems can be tried with inexpensive Fresnel prism that adhere to the lens and can be removed. The optics are not usually good enough for permanent use, but they help let you know how they work, and if that is something you want to pursue.

    All of these systems are rather costly and you are better off taking him to a specialist in low vision or neuro-optometric rehabilitation. It takes some knowledge to find the right solution for the right patient. There are frequently low vision centers in larger cities that may have resources if cost is a concern. He is lucky to have you helping him.

    Best Wishes

  72. Cathy May 26, 2012 at 9:04 am #

    Do you know a doctor in TX who does exactly what you do? I’m brain injured

  73. admin May 29, 2012 at 8:17 pm #

    Hi Cathy,

    What cities are you close to?

  74. Robert August 30, 2012 at 6:02 am #

    Hi Dr. Kisling,

    I just got my prism glasses to help me with my double vision. However, even when I am wearing them, I still have double vision. I don’t know what to do. Aren’t prism glasses supposed to alleviate double vision? I have a history of strabismus and amblyopia. Could this be due to it? Should I revisit my eye doctor?


  75. admin August 31, 2012 at 10:27 am #

    Hi Robert,

    Prism is used for double vision but sometimes the amounts are not quite right. You might take notes for your eye doc on when you seem to notice the double vision when wearing the new glasses. Is it all of the time or only with certain tasks? Does anything make it better or worse. (Looking to one side or up or down, or even at a certain distance). Strabismus can often vary depending on the viewing distance, head turn, and head tilt. You doc may be able to refine the Rx a little or it just may take some time or eye exercises to get your eyes working together.

    Best Wishes

  76. admin August 31, 2012 at 10:27 am #

    Hi Robert,

    Prism is used for double vision but sometimes the amounts are not quite right. You might take notes for your eye doc on when you seem to notice the double vision when wearing the new glasses. Is it all of the time or only with certain tasks? Does anything make it better or worse. (Looking to one side or up or down, or even at a certain distance). Strabismus can often vary depending on the viewing distance, head turn, and head tilt. You doc may be able to refine the Rx a little or it just may take some time or eye exercises to get your eyes working together.

    Best Wishes

  77. Yvonne September 5, 2012 at 4:36 pm #

    Just a quick comment. In the third paragraph, fourth sentence, the statement “An eye that turns up is hypotropic and one that turns down is hypotropic.” is saying both eyes are the same thing, hypotropic.

  78. admin September 6, 2012 at 9:53 am #

    Hi Yvonne,

    Nice perception! Usually we specify by the right eye though so there is an implied up or down right eye turn. But you are correct.

    Best Wishes

  79. Megan October 27, 2012 at 7:37 am #

    I have constant alternatinog esotropia and have fresnel prisms in my glasses. This helps amazingly with the double vision but badly reduces visual acuity. I’m constantly yanking my glasses off as I can’t see with them for conversation or computer use, or basically anything that isn’t distance. Also, can’t read street signs with the little prism stickers in my glasses. I’m supposed to get a new pair of glasses made with the prisms ground in but hesitate for the reasons listed about. And the cost is staggering. Any thoughts?

  80. Michael October 31, 2012 at 7:16 am #

    Dr. Kisling,

    Do you know of anyone who has prescribed prism eyeglasses to treat superior oblique myokymia (SOM)? If so, do you know how successful the treatment was?



  81. admin November 5, 2012 at 12:07 am #

    Hi Megan,

    The Fresnel prisms do degrade the optical quality of the image but they are cheap and can be used for very large amounts of prism. If the prism is being ground in it will not have the poor optics associated with Fresnel prisms. In this case, the cost should be worth the difference!

    Best Wishes!

  82. admin November 5, 2012 at 12:24 am #

    Hi Michael,

    I do not know of anyone personally who has used this method of treatment. It can be useful when the myokymia is precipitated by gazing in a certain direction. (So if you notice it usually happens when you look a certain way it is worth trying the prisms). I don’t know if you have tried any drug treatment but sometimes specific eye drops or oral medications can be useful in reducing symptoms.

    Best Wishes!

  83. Carolyn November 25, 2012 at 7:06 pm #

    I have Chronic progressive external ophthalmoplegia(CPEO) have had double vision when looking to the side for about 9 yrs.
    I have just picked up my prism glasses. I have a pair for reading/computer. the prism is 5.5B1 These finally seem ok, I am adjusting.
    I also got a pair for distance again prism 5.5B1 when I am wearing these I look straight and see double. I adjust my head a tad and it goes away. I am thinking these have not been made correctly, something is off.

    When the specialist at the store measured my face with that machine he didnt have it straight on my face.
    I am not sure if this would cause the problem-maybe the prism is off??? or if it is me having to get use to these.
    I have only had them for 3 days now.
    thanks for any advice!

  84. admin November 26, 2012 at 8:51 pm #

    Hi Carolyn,

    The first thing you might want have checked in the PD (pupillary distance or distance between where the center of the lenses are located). Since you have a separate distance and near pair, this normally a different number. When you read, the eyes turn in and decrease the pupillary distance by 3 to 5 mm. That can have a significant effect on the amount of induced prism if it is not accounted for. You also tend to look down a little when you read. If the ophthalmoplegia is a little asymmetric (different between the eyes- and it sounds like it is), you might have a need for a little vertical prism at distance (or near). That would be BU or BD. As you said, the prism could also be off in one pair. I would have them rechecked to make sure they are made to the prescription. While you are doing this, have them check the PD also- it should be a little different for the separate pairs. Finally, if those are both correct give it a few weeks. If your Doctor has not discussed CoQ10 with you you might want to ask about it. There are a few small studies that have shown a little improvement from this supplement.

    Best Wishes and Blessings!

  85. Jan December 17, 2012 at 5:17 pm #

    I am prescribed R 4base out and 1Base up. And L 4base out and 2Base down. I have recently had cataract surgery in both eyes. Double vision was not checked but prescribed same as in the past. Could the double vision have changed following surgery? Also why can’t the edges be thinned down? Thanks

  86. Tom December 30, 2012 at 2:27 pm #

    Hi I’m been to three different doctors and one Doctor is telling me I need a prism on an angle, not up or down. I have double vision where the objects are on top of each other. I know the bottom image is the correct image but driving ans seeing the center line floating is a pain.

    Event he eyeglass manufactures don’t think a angle prism can be make. Who is right?


  87. admin January 1, 2013 at 11:45 pm #

    Hi Tom,

    That is a really good question that I had to ponder on a little. Traditionally, prism is made base up or down, and also base in or out. An eyeglass prescription can specify (for example) 2 base up and 2 base in. This help move the image down a little and to the side a little (or help an eye that was turned up and to the side see things single). We can’t really directly measure how much prism is required at an angle in a clinic. What we can measure is how much an eye is turned up or down, combined with how much an eye is turned in or out. Here is where it gets a tad confusing (at least to me). When you grind prism into a lens and combine vertical prism with horizontal prism the end result is a vector that provides prism at an angle. I am going to have to check how this is done in the labs today. Just adding vertical or horizontal prism alone is fairly straight forward and is vertical (or horizontal) removal of a wedge of lens material. When you combine them, I believe with the older technology, the lens was modified effectively at an angle. In all likelihood, the digital surfacing technology used today generates prism at an angle also. (This difference from the concept we tend to hold in our heads of doing to separate procedures to remove material vertically then horizontally). Since we can’t measure at an angle we are more or less stuck thinking of prism the way we measure it. The end result is I believe both answers are right. You still end up with prism effectively added at an angle, but specified only by vertical and horizontal amounts. I will provide an update if I find out differently from the manufacturer. Thanks for giving me a little puzzle!

    Best Wishes

  88. Jared January 8, 2013 at 5:19 pm #


    I am really hoping you can help me understand something going on with both my head and vision recently. After receiving a prescription for prism lenses for the first time in July 2012, I had begun having some vision issues, particularly with nearer objects (like a PC screen), in addition to right side headaches and a scalp that is somewhat tender tothe touch on the right side.
    I cannot say it is ‘double vision’, but the general feeling is that both the right and left eyes do not cooperate when focusing on something. I do not have the typical wandering or turning eye issue, but these prisms were recommended when I mentioned to my doctor that objects close-up were harder to focus on. When I rely only on one eye (regardless of which one) the vision is more or less clear, but not when using both together.

    When reading the prescription, I assume the prism is 1.5BO for both eyes. With the astigmatism, the presc. reads as -7.00-2.25×180 1.5BO
    -7.00-3.25×170 1.5BO

    Do you have any thoughts as to whether or not after 6 months, this prescription:

    – could be causing the vision problems
    – my prescription could have changed again
    – a past post reply related to temporal arteritis could be to blame (A Nov. 2012 MRI was done on the head – which was clear of anything out of the ordinary – although I guess you need other tests done to confirm the Temp. Art.)

    or some totally different reason is the cause?

    Your insight would be most appreciated.

    Best regards,


  89. betty January 13, 2013 at 10:14 am #

    I need a very thick prism and wonder what type of lens to ask for, i.e.
    1.74 hi index or does it matter with prism?

  90. admin January 17, 2013 at 12:46 am #

    Hi Jared,

    There are a few possibilities. You are correct in thinking about temporal arteritis as it can cause scalp tenderness on one side. It can also cause esotropia, an eye turning in due to a vascular problem in the 6th cranial nerve. This nerve controls the muscles that turn the eye out, and a weakness on one side results in an eye turning in. It is possible to have a partial paralysis that only lowers the ability of the eye to keep turned inward on target. This would result in eyestrain and possibly blurriness with both eyes open as the eye is intermittently drifting off alignment in small degrees. When you close one eye, there is no need for the eyes to correctly align together so both images are aligned, and thus no eyestrain or blurriness. Since you have already had an MRI to rule out a problem from a tumor, you probably should talk to your doctor to make sure a recent ESR, or SED rate has been done. This is helpful in diagnosing temporal arteritis, although a biopsy is a higher (but more invasive) level of confirmation. Usually these more serious types of causes will create (at least in the short term) a non-concomitant eye turn or tendency for the eye turn. These tendencies are referred to as phorias, and in your case would be measured in prism diopters-thus you might have 6PD (prism diopter) BO (Base Out) prism at distance measured and 8 pd BO at near. The amount of prescribed prism would typically be less than the measured. In a non-concomitant eye turn, the amount of prism measured will vary with the direction of gaze. If your eye turn or tendency for eye turn is concomitant (constant in every direction you look), your concerns are not nearly as much. These types of eye turns are more typically from problems that were present at a much earlier age. In some people these only become problematic as time passes.

    Unilateral headaches are always a concern, since the majority of headaches from non serious reasons do not typically localize like this. Sometimes things don’t act “normal” and I have certainly seen a lot of people with headaches that occurred on one side from “non serious causes”, variations of migraines being the most common. Migraines can happen from eye muscle imbalances or the phorias that reveal a tendency for the eyes to turn.

    The amounts of prism needed can change over that short of a time period so you should have it remeasured. Prism is always a little bit of a guessing game to start with since the full amount is normally not prescribed.

    I would recommend (1) have the prescription checked right away to find out if it still meets your needs and while you are there find out if the problems is concomitant or non- concomitant. They may need to re-measure since most of us don’t do this the first time. (2) talk to your doctor about an ESR test. if neither resolves your problem, go see a neuro-ophthalmologist. They are a little harder to find, but usually very good in diagnosing the serious concerns. Hope this helps some.

    Best Wishes!

  91. admin January 17, 2013 at 1:24 am #

    Hi Betty,

    While that may seem like an easy question it is not for me at least! Spectacle lenses were initially just one spherical curve on the front and a different one on the back and only came in glass. When you look to the side of a lens, the angle through the lenses induces some optical distortions so they started adjusting the curvature on the front surface of the lens to create a better optical quality image. At some point, thinner lens materials came out to reduce the weight , thickness, and the bubble effect that some prescriptions have. The original plastic lens material has a 1.49 index of refraction. First came the 1.54, then 1.60, 1.67, 1.70, and now 1.74. As the number gets higher the lens is thinner but the different colors in light are spread out more and there can be some degrading of optical quality. You end up with a trade off between a thick, heavy, ugly lens and one that looks good but does not see as well. That being said, they have improved. The 1.60 index lenses are almost never a problem and many people wear the 1.70 and 1.74 without any complaints. Polycarbonate (which is about 1.59) is probably the worst material in terms of poor optical quality and stability). Many chain or big box optical stores push poly in some fancy sounding version- don’t go for it! The measure of this color distortion is the “abbe value”. Poly has an index of 1.59 with an abbe value of 30. A typical 1.74 index lens has a better abbe value even though it is much thinner. The strength of your prescription plays into this since the difference in a -1.00 is not nearly as profound as a -6.00 power. Once you use these higher index material you also need to add a quality anti-reflection coating since the reflections typically increase.

    You have made it this far sooooo! Move forward to the 90’s as the “Star Wars Strategic Missile Defense” started by President Reagen was moving into development. There was a need to overcome the atmospheric distortions that altered the light waves generated by LASERS used to guide the defensive missile technology. “Adaptive Optics” was a method invented to do just this. Fast forward a little more and this was “adapted” to measure distortions in the optical system of the eyes. With a little more work we have come to understand that lenses are very imperfect things. With the old “corrected lenses” mentioned above, we know when you look to the side in a lens that corrects for astigmatism (which most people have at least a little), the correction is off. The angle the frame tilts the lens, and the angle the frame bends horizontally around your face also degrade the optical quality. The distance you look, how the lens ios centered in the frame, how far away there frame is from your face- well it’s a long list of things that degrade the image in variations of math that as far as I’m concerned are best left to those missile people.

    What is changing is the way lenses are manufactured today. The new technology is referred to as “Freeform of digitally designed lenses”. The old technology (which is perfectly adequate for many lower prescriptions), produces lenses accurate to about .10 diopters. The new technology is not only 10 times more accurate, but can do this accuracy in curves that vary across the back of the lens to compensate for many of these optical abberations induced by the things I listed above plus many more. These so called “atorics” freefrom lenses are kind of like a lens individually designed for you ( only sort of but that’s a different story). I believe when prism is ground into the lens it is probably much less likely to create more distortion if it is digitally surfaces, but I need to check on that.

    The end result is, for higher amounts of prism in higher prescriptions a digitally designed freeform lens is probably your best bet. Using a 1.60 index material at minimum will help offset some of the added thickness prism creates. I would probably opt for the 1.67, and be sure to add a good anti-reflection coating on the lens. Use a smaller, rounder frame if you can; you will significantly reduce lens thickness by doing this!

    Best Wishes!

  92. admin January 17, 2013 at 2:23 am #

    Hi Jan,

    It could have changed after the surgery but you should have increased symptoms of more eyestrain or double vision if that were to be the case. I’m not sure but it sounds like that is not going on with you so it is probably OK. A prism is really two straight edges at an angle to change the direction of light without altering the focus. That just another way of saying you need the added thickness for it to work, at least with our current technology. Next time, try using the smallest, roundest frame that will work with your prescription in a hi index material (at least a 1.60 preferably a 1.67. Add an anti-reflection coating, and you might be a little surprised how much that softens the thicker edge!

    Best Wishes!

  93. admin January 20, 2013 at 5:42 pm #

    Hi Suzanne,

    Sorry for the rather long delay in replying. Every once in a while something slips by me and I only discover when going back through the older comments. While the increase could be due to various medical issues, it is probably unlikely in your case. Strabismus surgery for eye turns is still not all that accurate for a variety of reasons. It can be caused by muscle that are too strong, too weak, inserted abnormally, and also by tendons in similar manners. Crossed eyes are also associated with nerve centers in the brain-stem, and they may receive too strong or two weak of an electrical impulse. This may occur from birth or be the result of a disease process. The nerve can be compromised along it’s pathway to the eye muscle by an abnormal route that is traversed, from compression due to a smaller than normal pathway, disease, or trauma. The receptor sites of the individual nerves may be altered from birth or from a disease. The neurotransmitters that influence the transmission of the electrical impulse to the eye muscle may be altered from birth or disease.

    Even more compounding, the amount of focusing and attention to visual objects can greatly alter the amount of eye turn that is measured, and thus surgically corrected. How well your eyes are able to work together and fuse the world into a single perception can vary with age and fatigue, and what correction you need today may not be adequate tomorrow.

    The end result of my soliloquy is that one year after strabismus surgery the success rate is reported as between 60-80%. Success is defined by different means, and usually does not included eyes that are aligned with true stereo vision and no episodes of double vision. It is more realistic to look at strabismus surgery twofold:
    (1) Cosmetic, especially for adults. That implies that the eye turn is not noticeable to most people. That can be no small concern as you probably know.
    (2) Reduction in episodes of double vision. A successful outcome would be one where the incidence of double vision was greatly reduced and occurring primarily when you were very fatigued.

    Looked at this way, strabismus surgery is not so bad in it’s outcomes. You have the potential for surgery to be done in a number of different ways, attaching the muscle farther back or closer. One surgery is frequently not enough for ideal long term outcomes. It is not unusual to have regression over time like you described. I would talk to your surgeon again if you have not dome so already. The other possibility is orthoptics, or eye exercises. Normal relationships between eye muscle do get altered after surgery so it may not work. There are also a number of variables that determine whether orthoptics is applicable to an individual case, such as the size of the eye turn. Usually (surprise) surgeons don’t believe in orthoptics at all and (surprise) docs who primarily do orthoptics for eye turns don’t believe in surgery.

    Most of all I would recommend being under the care of someone who has your best interest at heart, and proceed as an informed healthcare consumer.

    Best Wishes!

  94. Tim January 29, 2013 at 8:45 pm #

    Dr. Kisling, I submitted a question a few days ago about prism glasses, but my circumstances have changed and I now have an appointment with a neuro opthalmologist to discuss the issue and to get advice. I still would be very interested in your thoughts, though, if you have some time to respond. thanks

  95. Tim January 29, 2013 at 8:55 pm #

    I saw recently that Hillary Clinton is wearing prism glasses and now am wondering if I should try the same–i have been diagnosed with “bilatral cranial nerve 6th plasy.” From what I have read, I get the feeling that neither the prism nor the surgery options are guaranteed to resolve my problem permanently. I realize prisms are a stop gap–but how do I determine the likelihood that my diplopia is likely to correct itself so that I will not need surgery? And if I opt for surgery, how likely is my vision to change post-surgery so that I will need repeat surgery down the road?

  96. Dr. Kisling January 29, 2013 at 10:57 pm #

    Hi Tim,

    With the type of eye turn you are experiencing, there does tend to be some healing over 6 to 12 month period. This can vary by what the underlying cause was that resulted in the strabismus, or crossed eye. Since it is bilateral, I am presuming that there was a problem close to the center where the nerve originated from. The difficult part about an extended recovery time frame is the degree of turn will likely vary. This does make it hard to have a one shot surgical or prism cure. Added to that is the way muscle contract under constant strain (the opposing muscle to the weak one), and the way muscles act in three multiple ways depending on the direction of your gaze.

    That’s where the “Hillary” prism glasses come into play. If you look closely at the pictures of her newest eye wear (something I’m sure she hates to do!), you will notice tiny vertically oriented lines across the backside of the lens. This is a thin membrane vinyl composed of numerous prisms known as a Fresnel prism (after a French physicist Augustin-Jean Fresnel born in 1788. Since the lines are vertical, the prism is horizontal in her case. It is also across the entire back surface of the left lens, so it is probably being used for a horizontal eye turn problem similar to what you are experiencing. These lenses were initially used for lighthouses, then automobile headlights. They have many different applications today. Because multiple prisms are used, they are much thinner and lighter than a regular prism would be. On the down side, they are not very attractive as I am sure Secretary Clinton agree. They also degrade the image quality, so there is a balance between vision clarity and double vision that needs to be weighed.

    Fresnel prisms are great for cases like yours. They are inexpensive and easily applied in a temporary manner to the back of your lens. They can help compensate for large degrees of eye turns, and due to the low cost, they can be readily altered as the healing process occurs. For the next 6-12 months it may be just what you need.

    Other options are used including surgical procedures to weaken or strengthen muscles, moving muscle attachments to help alter and balance their function, and even procedures to help stabilize the eye in straight ahead gaze (at the expense of an increase in double vision when looking to the sides). Botulinum toxin has been injected into muscles to help lessen double vision and/or prevent permanent contraction of opposing muscles. It sounds pretty horrible to inject one of the most toxic substance known, but the doses used are so low that it really is a safe procedure.

    You really need to discuss your options with the doc that is treating you. If they can’t communicate all of your options in a manner that is clear and complete, seek a second opinion. I would certainly want to explore the use of Fresnel prisms for the nest 6-12 months if it was one of my family members. The risk is almost negligible other that the possibility of muscle contractures and needing to change them over time (and they aren’t the most attractive thing to greet you in the mirror first thing in the morning). At the end of 6-12 months there is always the chance to re-evaluate options.

    The only other thing I would recommend is trying to get the best understanding you can of why the problem happened in the first place. There may be underlying health conditions you can take preventative measures for now that will greatly effect the quality of your life in the future. It is extremely tough to deal with double vision, even with fresnel lenses. Double vision, or just the effort to try and keep it at bay, create a large drain on mental capacity to read and process visual information. Keep that in mind and don’t be too hard on yourself as embark on the steps to compensating for and curing this problem!

    Best Wishes!

  97. Dr. Kisling January 29, 2013 at 11:02 pm #

    Hi Tim,

    Read my previous post. A neuro-ophthalmology consult is the right track, as a rule they are almost always top notch in diagnostics and surgery. If you decide to go the prism route there are neuro-optometrists who do a great job at that. You could probably find one at the patient portal of NORA

  98. Tim February 12, 2013 at 12:15 pm #

    Dr Kisling,
    thanks very much for your responses. I visited the neuro opthalmologist this month and now wear a 9 diopter Fresnel lens on one eye. It makes a huge difference. I have had diplopia since a bad fall nine months ago, and this is the first week in 9 months w/o double vision. It is so nice to have close to normal vision again…at least when wearing the prism and when looking straight ahead. My near vision actually is almost normal without glasses or prisms, it is the far vision and side vision that doubles. But I will continue with a neuro opthalmologist and see how things develop. Since I am in my ninth month of diplopia, am thinking of consulting a surgeon to get feedback on how much longer I should give the healing process before deciding whether to go with surgery. As appreciative as I am for the prisms, I am thinking that since I am almost at the end of the 12 month healing period and since I still have diplopia without the prisms, maybe I should look in to surgery. Thoughts?

  99. Stacy February 17, 2013 at 4:20 pm #

    I have been cross eyed since birth. Every time something crossed my line of vision my eyes would cross. They don’t just cross to the sides they will cross anyway that they chose to cross. My left eye is a lot worse than my right eye. I dealt with the crossing of my eyes until a few months ago when I saw that my eyes started to cross even worse than they did before. My eye doctor said that he wanted to try prism lenses to see if it would help. I have been using my lenses for about 5 months now and I see a big difference. My eyes don’t cross as much, but they do still cross when I am overly tired or stressed. Another thing I have noticed since using these glasses I have been so tired and moody. Is there any way that using prism lenses can effect my mental state? Also my eye doctor said he gave me the highest prescription of prism that he could. If he did give me the highest he could does that mean treatment stops for me unless I get surgery? Thank you for responding.

  100. Dr. Kisling March 3, 2013 at 9:33 pm #

    Hi Stacy,

    With strabismus, or crossed eyes, it is very common for the problems to be worse with fatigue, stress, and lack of sleep. I wish there was a good answer to your question about the fatigue and mood changes from the prism but there is very little research along these lines. There are a number of factors that could play into it. When binocular vision breaks down (the two eyes not working together to form a unified single perception of the world around us) there is a resultant stress on the visual system while it tries to cope with seeing two images. As with any physical stressors, there can be an overlap with your mood. The perception of two objects instead of one can lead to anxiety and other problems. If you think about the consequences to our forebearers, visual confusion could be deadly when they were threatened by something like a saber-toothed tiger-so it’s not so surprising that you could feel the same way. At times, adding prism to a correction could decrease the frequency of your eyes crossing but also break down some of the suppression (or turning off of part of the vision in one eye) resulting in more visual stress as your eyes work overtime trying to fuse the images from each eye into one. It could also create some problems if you start experiencing 3D vision intermittently. That is not necessarily a bad thing since it can be another cue to help you know how to align your eyes.

    There are limits to the amounts of prism that can be incorporated into an eyeglass prescription. Some of this is determined by the amount of prescription you have and the size and shape of the eyeglass frame. You could have a second opinion to make sure you are maximizing what you have but my guess would be your eye doctor is probably correct. Some forms of strabismus are very treatable with vision therapy, a form of eye exercises to improve how the eyes work together. Surgery has more variable outcomes, especially in adults. Strabismus surgery in adults is usually more aimed at improving how the eyes appear, while binocular vision and 3D vision is a less likely outcome. You might want to check Dr Maino’s web site at

    Best Wishes

  101. Kathy April 24, 2013 at 12:53 pm #

    Dr. Kisling,

    I was originally prescribed prism lenses 2.5 years ago. I didn’t notice a problem but while in for my annual eye exam, the doctor noticed that I could be seeing double. It took a while to adjust to the prisms, longer than usual for a new prescription. Then at the next year’s eye exam, the doctor said the test for double vision showed that I really didn’t need as much of a prism as I had so he suggested I go back to my pre-prism prescription. My vision was so blurry (I had a stressful job using a computer all day so work and driving to work were difficult) that I asked to switch back to the prisms after 5 days of trying the non-prisms. The doctor mentioned at my next visit that had I been able to give it more time I may have adjusted to the non-prism lenses as my eyes did not seem to need them. In fact, over the years, my eyes had gone from requiring a very slight prism (which he never prescribed and I was fine), to no prism, to the necessary prism. So now I have decided to try the non-prism lenses (18 months later) again, partially because if my eyes are switching back and forth at each annual examination between prisms and non-prisms, I may as well get my eyes accustomed to non-prism. How long should I try the non-prism lenses before I give up and go back to the prism lenses? I know it is bad to switch between prism and non-prism on a regular basis. Is it possible that my eyes may switch back and forth like that over the years? Is it possible to become accustomed to the prisms and require them even when they are not medically necessary based on the eye exam in a particular year?

    Thank so much.

  102. Dr. Kisling April 26, 2013 at 8:21 pm #

    Hi Kathy,

    My usual rule of thumb is people are about 75% adapted at 3-4 weeks and fully adapted after 3-4 months. So if you try it without the prism and it is unbearable at 3 weeks you should probably go back to the prism. If it is OK but not great at 3 weeks you might want to give it another 2 months.

    In my experience tests for prism are notoriously unreliable. We stick a big black instrument close to your face and are always surprised when the findings aren’t all that accurate. If you have it tested a few different ways you get a little but of a better idea. Even then, the best way to check is correlating findings without instruments (using hand held prisms) and correlating that with actual symptoms. Many eye docs would disagree, but I don’t like trying to fix problems that have no symptoms. I think it is reasonable to try the glasses without the prisms and seeing if the symptoms of blurred vision and eyestrain don’t return.

    Depending on the type of prism correction, there can be a tendency to require more prism over time as the eyes adjust. Other types of prescription such as vertical prism will not show this type of issue. Any prism correction can vary with fatigue and your overall level of health. Your normal ability to keep the eyes working together lessens when you are tired. So it is possible that from year to year the prism amounts could change. More rapid changes could indicate some underlying health issues. If you were to find larger swings in the amounts of prism needed over several weeks or months you should seek further answers.

    It sounds like you are dealing with smaller amounts of prism so I don’t thinks that is the case. The other option is trying some visual therapy or eye exercises. In some cases this works very well depending on the type of muscle imbalance. Eye therapy is also subject to degradation over time so it may need to be repeated. These imbalance can be due to faulty muscle insertions, ligaments, muscles (or ligaments that are too short, too long etc.). Often it is not the muscle at all but the nerves or the nerve center that tells the muscle how much to contract or relax. Usually eye therapy is effecting the flow through the nerves instead of the actual muscle. Prism is letting the eye remain turned a little or letting it stay straight without as much of a nerve impulse. All of this verbiage is a long way of saying that it is not so straightforward to measure or prescribe a set amount that will always be correct in the future. My best advice is to do what”feels good” and if you give it adequate time and it doesn’t feel good go back to the way that did. No one has ever been addicted to prism or had it damage their eyes to my knowledge. On the other hand, if you are driving down the highway going 75 mph squinting, rubbing your eyes, seeing double-well that’s not always a good thing!

    Best Wishes!

  103. Kathy May 2, 2013 at 4:31 am #

    Thanks a bunch, Dr. Kisling, for the response. I switched back to the prism lenses after a week as I was squinting while driving and seeing double at times. I have worn glasses since 3rd grade so wear them every waking hour – my correction is quite strong, even before the prisms were added. Seeing clearly with my glasses is very important to me. Thanks again for your time.

  104. Debbi June 25, 2013 at 9:14 am #

    My child is 10 and had vision therapy for a year to help convergence insufficiency. He has made great strides but we are not completely happy with how he reads yet. Someone told us that prism glasses would help him. What do you think?

  105. Dr. Kisling June 29, 2013 at 10:37 pm #

    Hi Debbi,

    Most of the time prism glasses will not help with convergence insufficiency. Convergence insufficiency is characterized by exophoria at near (eyes that want to turn out when working up close or reading) and a reduced point of near convergence (eyes that do turn out before they should when you track an object getting closer to your face). Some studies have indicated that the best treatment for convergence insufficiency is vision therapy in office sessions. A recent study found home therapy was no better than placebo treatment. The effect of prism glasses on convergence insufficiency has had very few studies and does not appear to help most of the time. There is rapid adaption to the type of prism used for exophoria in many people which renders the glasses ineffective. If there is a difference in the amount of exophoria at near distances compared to far away distances it may be difficult to leave them on. There probably are some cases where prism does help with convergence insufficiency. Some people will not undergo rapid adaptation, and some cases of micro eye alignment errors may benefit. People who have head significant head injuries often show an unusual response to prism and it may help with convergence insufficiency. Convergence insufficiency is usually thought of as being sue to the exophoria but it probably is not that easy. I often see eyes that cross turning out at 16 inches or more with little exophoria. There is a delicate balance between accommodation (focusing) and convergence (eyes turning in to track an object as it gets closer). It also includes a complex fusional process where the separate images of each eye are turned into the perception of one 3D image. Attention, peripheral vision, alertness, and a number of other factors are part of this process. If a child is struggling with print that blurs and doubles reading will definitely suffer. Reading is a learned skill, and your child could be suffering from gaps in learning when the convergence insufficiency was still being treated. If their vision is now comfortable and without eyestrain or other symptoms, it might be more productive to have an evaluation and some help from a reading therapist or occupation therapist. I encourage you to ask your child’s optometrist if this might help.

    Best Wishes!

  106. Dr. Kisling June 29, 2013 at 10:37 pm #

    Hi Debbi,

    Most of the time prism glasses will not help with convergence insufficiency. Convergence insufficiency is characterized by exophoria at near (eyes that want to turn out when working up close or reading) and a reduced point of near convergence (eyes that do turn out before they should when you track an object getting closer to your face). Some studies have indicated that the best treatment for convergence insufficiency is vision therapy in office sessions. A recent study found home therapy was no better than placebo treatment. The effect of prism glasses on convergence insufficiency has had very few studies and does not appear to help most of the time. There is rapid adaption to the type of prism used for exophoria in many people which renders the glasses ineffective. If there is a difference in the amount of exophoria at near distances compared to far away distances it may be difficult to leave them on. There probably are some cases where prism does help with convergence insufficiency. Some people will not undergo rapid adaptation, and some cases of micro eye alignment errors may benefit. People who have head significant head injuries often show an unusual response to prism and it may help with convergence insufficiency. Convergence insufficiency is usually thought of as being sue to the exophoria but it probably is not that easy. I often see eyes that cross turning out at 16 inches or more with little exophoria. There is a delicate balance between accommodation (focusing) and convergence (eyes turning in to track an object as it gets closer). It also includes a complex fusional process where the separate images of each eye are turned into the perception of one 3D image. Attention, peripheral vision, alertness, and a number of other factors are part of this process. If a child is struggling with print that blurs and doubles reading will definitely suffer. Reading is a learned skill, and your child could be suffering from gaps in learning when the convergence insufficiency was still being treated. If their vision is now comfortable and without eyestrain or other symptoms, it might be more productive to have an evaluation and some help from a reading therapist or occupation therapist. I encourage you to ask your child’s optometrist if this might help.

    Best Wishes!

  107. Margaret July 5, 2013 at 9:21 am #

    I read all the questions and found one on Dec 11, 2011 from RG. I’ve had the same thing and have looked for over 13 years for help. I had LASIK and it gave me esotropia within a few weeks. No doctor knows why. I have been to doctor after doctor after doctor. I am now wearing a press on prism and hate it. I can see single vision within about 18″ but after that my vision doubles and my eye turns in. Actually, I think I can make either eye turn in. I have the press on because the doctor said I guess a ground in prism would be so very thick so it’s done for cosmetic reasons. I continue to look for answers. Do you know why this happened to me? I really don’t want to have eye muscle surgery.

  108. Dr. Kisling July 25, 2013 at 5:42 pm #

    Hi Margaret,

    There are a few reasons why people might end up with esotropia after LASIK.

      If myopia or nearsightedness has been over corrected you have to focus more for reading and this is tied to turning the eyes in
      Clarity of vision fluctuations after surgery can decrease the details you see to the extent that the way the eyes work together breaks down
      The dominant eye or the degree of dominance could change due to changes in the prescription difference between eyes or clarity of vision after surgery

    Most of the small number of cases that have occurred seem to be in people that were corrected for myopia and had some previous disorder in how their eyes worked together, even if it was not causing problems prior to surgery. In most cases the patients ended up with esotropia for near vision, or eyes that turned in. This can be very disrupting to daily living as you have experienced. I would suggest seeking out an optometrist in your area that does vision therapy for strabismsus. If you do not currently need a bifocal lens your eye turn might benefit from one. You also could benefit by wearing a stronger bifocal than what you actually need. If you do not find the help you need I would keep looking. The C.O.V.D. (College of Vision Development) maintains a member listing which might help. Dr. Dominick M. Maino, OD at the Illinois College of Optometry would also be a good resource for the type of problem you are experiencing.

    Best Wishes

  109. Debbie September 5, 2013 at 7:58 am #

    I was diagnosed with Vertical and Horizontal heterophoria and have been given horizontal and vertical prisms with progressive lenses. I was told that as the muscles relax, additional prisms maybe required. I was told that I should adapt quickly to the prisms and progressive lenses, but that has not happened. I have been wearing the glasses for about 5 days, so should I give it more time?

  110. Dr. Kisling September 21, 2013 at 6:53 pm #

    Hi Debbie,

    Adjustment to progressive lenses is pretty fast today for most people. There are some of us who adjust a little slower. My rule of thumb is you are usually about 75% adjusted at 3 weeks but the last 25% can take a few months. If someone is having horrible problems at 3 weeks they probably won’t adapt, but if it is OK but not as good as they would like it’s worth hanging in there for a few months. Prism is a little harder to adjust to depending on the amounts. I would give it a few months unless you are having intolerable headaches and nausea when you wear the glasses. Hope that helps.

    Bets Wishes!

  111. Victoria October 14, 2013 at 4:15 pm #

    I was born with a lazy eye and at 10months my mother took me a specialist. They fit me with glasses, they also had me do the patching. At that age I didn’t tolerate eye drops and my mother said that the doctor offered to fix my eyes with surgery, but as a young girl, I can’t recall my mother ever mentioning it (surgery). I had other specialist along the way; however, even if my eye was not straight I dealt with it until I started driving at night. I went to see an optometrist who fit me with glasses and added a prism in my lens to help me see at night. I wore them for a bit and started seeing double. I went back to the optometrist and told him that I can’t stop seeing double. He referred me to a specialst, this was in 2005…I dealt with a specialist who was puzzled and he referred me to another specialist…and that specialist referred me to another specialist…I was passed onto several specialist that didn’t know what to do with me. I was 28 years old when I started seeing double and I’m already 37. I had one strabismus surgery and 3 different botox injections and several prism changes. The doctor told me that my double vision up close is different from my distance double vision. He didn’t want to mess with my eyes. I’m really frustrated…I want to stop seeing double. I use an eye patch when i can’t tolerate it anymore. I sometimes don’t wear my patch at work because it brings attention to me and people start asking questions or make pirate comments, “Arrrghhh!!!” Or ask me if I’m a Raider Fan…I’m really tired and sometimes I get depressed. I keep on asking myself why me. Why is it that I’m the one with the screwed up eyes and my twin is not. I realize that if I stop using my eyes, like being on the computer for days like I am at work, it improves, but as soon as I start using a computer or a small hand held device, my double vision gets worse, even if I’m not using a computer and I’m using my eyes to read papers, my double vision gets worse. Is there a light at the end of the tunnel? Will I be able to turn off the double vision that was caused by a prism? This really affected me getting jobs that I really wanted in law enforcement. I have strabismus, amblyopia, myopia, estropia (left eye) and diplopia. I can’t see far away and I noticed that I’m struggling to read the fine print on medication bottles. Even my mother offered to donate her eyes to me when she died. I told her it’s more complicated. I want to get rid my diplopia forever.

  112. Dr. Kisling December 11, 2013 at 9:52 pm #

    Hi Victoria,

    It sounds like you have been through a lot. My best suggestion would be to make an appointment at the closet College of Optometry to where you live and see the resident expert on binocular vision. Other than that you could use two different pairs of glasses, one for distance and one for near. That way the prism could be varied for each distance. Sometimes a multifocal lens can help if the eye turn is for more esotropia at near than distance. It is also possible to use a contact lens with an small opaque area in the center in place of an eye patch. Vision therapy might help. I do not think the prism precipitated the diplopia, it probably was more of two independent events occurring at the same time. Don’t write of prism as a solution to your current dilemma.

    Best Wishes!

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  113. Sally Clark March 6, 2014 at 7:22 pm #

    hey all,
    I have worn glasses since i was 7 and Im now 32 so that is fine. although I have just started wearing glasses with a prism 7 weeks ago. i have had continual head aches since. in between both my eyes and on my forehead. Im not sure if it is the glasses/my neck/sinus or maybe something worse. I have had 4 doses of antibiotics for sinus so Ive ruled that out and am booked in to neautrologist and a bowen therapist but thought it could be as easy as just going back to my old script.
    Im very sick of having a headache because its ruining my life! I guess Im interested if this is the location for where a headache would be if it was caused by the prism. Im also feeling kind of seedy but i can see fine. thanks in advance.

  114. Dr. Kisling March 25, 2014 at 7:38 pm #

    Hi Sally,

    A lot of people get headaches when they first start wearing prism in their eyeglasses. After 7 weeks you should have most of the adaptation to the prism possible. The headaches are usually described as “eyestrain, pulling on the eyes, behind the eyes, on the front of the head or sides, and possible a hatband type of pain pattern. They are usually on both sides of the head, or if not, they appear on different sides of the head at different times. Going back to the old prescription should answer the question but I would suggest talking to your eye doctor first. Sinus problems can certainly create headaches and it is hard to rule them out as a cause without having xray images of the sinus cavities around the eyes. I think you are wise to see a neurologist. Any chronic headaches, especially headaches that are getting worse and/or occurring only on one side of the head warrant a visit to the neurologist.

    Best Wishes!

  115. Wendy Catto June 16, 2014 at 9:53 am #

    My mother has recently been diagnosed with Parkinsons as well as Visual Midline Shift Syndrome. She was prescribed Yoked Prism Glasses and immediately upon putting them on had about an 80% improvement in her balance and ability to stand and walk which was amazing. Unfortunately after only 3 or 4 days the effect seems to have worn off and now they make her dizzy. She went back to the Optometrist to see if they could make an adjustment but was told to just keep wearing them all of the time. Does this sound right?

  116. Karen July 18, 2014 at 3:09 pm #

    I have just been given a prism in just one side of my glasses. Why just one and don’t I need some exercises.

  117. Dr. Kisling July 21, 2014 at 9:38 pm #

    Hi Karen,

    Prism in front of one eye effects both eyes. Since adding prism adds thickness to the lens the typical reason to add prism to both eyes is to balance the changes in thickness. With lower amounts of prism it is not necessary. I usually adhere to the line of logic that the simplest way to solve a problems is usually the best. If your eye problem can be resolved by adding a little prism to one eye and you need the glasses anyway, why spend extra time (and money) on therapy. Hope that helps.

    Best Wishes!

  118. Dr. Kisling July 22, 2014 at 7:24 pm #

    Hi Wendy,

    Fortunately you found an eye doctor who even recognizes midline shift syndrome. Depending on the case specifics what they are doing is not unreasonable. Sometimes yoked prism is used to reacquaint the patient with the neglected side of their body. Sometimes it is used intermittently to either adjust posture or disrupt the habitual posture. Discuss with the doctor what they are trying to accomplish. If you don’t get an explanation that makes sense you might want to try a second opinion.

    Best Wishes!

  119. jodi August 6, 2014 at 6:32 am #

    I wonder if you can help. I would like to know what the result would be if the prism, fitted in glasses as a prescription, was fitted the wrong way. The prism is to correct a near convergent squint with tight medial rectus muscle and double vision.
    Your response would be very much appreciated.

  120. Dr. Kisling August 18, 2014 at 4:28 pm #

    Hi Jodi,

    If the prism was put in the wrong way it would likely increase the amount of double vision and the separation between the two images. There would probably also be an increase in eyestrain.

    Best Wishes!

  121. Lyndsay Holbrook September 24, 2014 at 10:18 am #

    Dr. Kisling, I had bilateral eye muscle surgery on both eyes to correct the turning inward. I also have to wear glasses or contacts for my vision. After the surgery I saw two different doctors and they prescribed me prescriptions for glasses. The prescription was very similar the only difference was one had prism in it and the other did not. I was wondering what prescription I would be better off going with and if choosing the prescription with the prism in it with reduce the effectiveness of the bilateral eye muscle surgery.

  122. Dr. Kisling September 25, 2014 at 11:51 pm #

    Hi Lyndsay,

    I would try the prescription with the prism in it first to see if it is more comfortable and helps you maintain single vision better. It actually is better if it works since it helps the eyes to work together. If they can’t keep aligned on the same point the surgery could be wasted. You can always lessen the prism later once your capacity to maintain single vision is solid. You could think of like a jet runway that allows the plane to get up to speed and get in the air. Without the runway it never has the capacity to fly. Without needed prism, the eyes might never get a chance to fuse two images into one and work together. Hope that helps.

    Best Wishes,
    Dr Dave

  123. Michelle October 3, 2014 at 10:52 am #

    Dr. Kipling’s had a couple of answers that answered the question I have, but they seemed to be contradictory. I had a prism of 3.5 BO in each eye for about 12 years. Then it changed to 6.0 last year, and 7.5 this year. I never noticed any improvement in my vision with each change (and never any double vision before the change). I quickly adapted to the prism changes but could also go back to the prior set of glasses and see fine. My question is if these prism increases could be causing more prism increases? Dr. Kisling first said that a prism does not permanently damage the eyes, but then said as the eyes adapt, they could need stronger prisms. These two seem to contradict the other. I am wondering if I should stick with the 6.0 prism since I see the same as the 7.5 ones and with the 7.5 ones, the next exam could show an increase needed yet again at my next exam.


  124. Dr. Kisling November 11, 2014 at 8:15 pm #

    Hi Michelle,

    Prism will not damage your eyes. There is adaptation in some cases to base in prism but typically not to base out prism. Sometimes the need for prism increases over time but this is not adaptation, it is more likely related to fatigue and sometimes changes in focusing. When you focus there is an automatic amount of convergence (turning in of the eyes) that goes along with it. In some cases people will use focusing to compensate for uncorrected far farsightedness and end up with eyes that turn in. If the farsightedness is fully corrected they drop the accompanying turning in and need less base in prism. Someone who is very fatigued may need more prism to keep their vision clear. Your body can change overall and change the amount of prism you need. We have our rules for the amount of prism to prescribe but really they are just guidelines. Normally the lowest amount of prism needed to give you clear, comfortable single vision is the right amount. Too much prism could cause eyestrain and double vision, but it would go away as soon as you had the correct amount. Hope that helps.

    Best Wishes

  125. Brenda McAllister January 15, 2015 at 4:35 am #

    This “prism” stuff is new to me. But Stickler’s Syndrome is not. Detached retinas started at 12; had intraoccular implants in each eye before 30 with follow-up YAGs; diagnosed with glaucoma 2 years ago. In 2011 a victretomy and Schleral buckle repaired a major retina tear in my right eye. After the surgery, for the first time, I began to have double vision only long distance. Now driving is near impossible. By habit I close my right eye when driving. I’m 56, have diabetes, and high blood pressure. Am I a candidate for prism glasses since I only need them for long distance or should I just find someone else to drive for me? Are there any more alternatives than prism eyeglasses, eye patches, or simply closing one eye?

  126. jawad shafqat January 23, 2015 at 7:16 am #

    my father is experiencing double vision binocular diplopia since 2 weeks.Doctor has done hess charting test and with tests have found out damage to sixth nerve on left eye with limited father is diabetic for 20 years..recently his BS levels were very high but now we have started insulin and BS levels are undercontrolled..Doctors say it will take 3 months but he is a driver so he needs immediate solution till in 3 months eye sight will return to prisms in eye glasses but one of the doctor has contraindicated prisms as he said we prescribe prisms in cases in which diabetic diplopia is permanent but i need solution..recwntly he has taken lyrica 100mg for leg neuropathy and now i have started neurobion injections ..please tell me prisms are safe to use or not as some say it will stop the recovery process.t
    thanks alot.

  127. Dr. Kisling April 12, 2015 at 5:40 pm #

    Hi Jawad,

    Prism are safe to use. Press on fresnel prisms work great in a case like this and they can be replaced with lower amounts as time goes by. They do degrade vision so depending on driving demands you still may have to use regular prisms in a temporary prescription. Have them use the minimum amount needed so it will last a little longer.

    Best Wishes!

  128. Dr. Kisling April 12, 2015 at 5:48 pm #

    Hi Brenda,

    It’s always nice to be driven around but…. You could use a distance only paor just for driving. Another option would be a custom contact lens with an opaque center. You could try putting a small circle of opaque scotch tape in the center on a pair of glasses in the right eye also.

    Best Wishes!


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