Worried Your Eyeglasses Prescription Keep Changing Until You Go Blind?

Dr. Kisling Common Eye Questions for Your Optometrist Leave a Comment

A commonly heard question in my optometrist eye care center is will my eyeglasses prescription keep changing? Followed frequently by will I go blind? The latter is a common misperception based very slightly on fact. People due lose eyesight and suffer loss of vision from degenerative myopia or nearsightedness. There is a significant  increase in the percentage of people who  get retinal detachments in the nearsighted population. However, even though this is a significant increase, relatively speaking it is extremely rare. A very small segment of the population do have degenerative nearsightedness. This is a pathological state of the eye where it progressively gets worse at a rapid rate and causes a number of serious vision problems including retinal  detachments, glaucoma, cataracts and retinal degenerations that can cause blindness. This condition is evident in adolescence and if you have to ask you don’t have it.  Degenerative myopia has a reported incidence of 2% in the United States, and is the seventh leading cause of blindness. It is more  common in Chinese, Jewish, Japanese and Arab populations, and women. In my patient population the incidence is much lower, probably less than .02%. It probably has some dependence on how pathological myopia is defined, if it is not sight threatening or decreasing vision I don’t categorize it as pathological nearsightedness. Progressive myopia is associated with some systemic diseases like Marfan’s syndrome (probably what Abraham Lincoln had), retinopathy of prematurity, Ehler’s-Danlos syndrome, and albinism. You would probably know if you had any of these conditions. The prescriptions in degenerative myopia are typically so high at an early age that they are probably 5-10x worse than what you currently experience. All that being said, when will your eyes quit changing? Personally I believe all of the studies are outdated. Years ago when a child reached adolescence the eyeglass prescription stabilized. The periods of rapid body growth seemed to correlate fairly well with eye growth. The period of change has gradually extended out in time. First you have to define what stable means. To some, it means a change of 4 steps which in optical terminology is one diopter. Past studies have indicated myopia develops in about 20% of people over the age of 20 who go back to school (or live in restricted near environments like submarines). If you decide 3 steps is change instead of 4 then this number goes up to over 40%. Define it as 2 steps or less in a year (0.50 diopters) and the numbers go even higher. The one thing that is indisputable today is that blurred vision is a stimulus for change in your glasses prescription. What is not clear (pardon the pun), is what this really means. Under focusing, over focusing, fluctuations in focusing may all cause blurred vision. It may take seconds or hours to start the process. Current research indicates it is not central vision but peripheral blurred vision that may cause visual changes. From the studies of changes in vision in older students it is clear to me that there are genetic and environmental factors at work. Authors of some studies do not think the research substantiates an environmental factor, only the age of onset of myopia-I disagree. What I believe is our world is exponentially changing into a near centered environment (i.e. we all live on the internet where you are now). This is not a normal visual environment and probably not the healthiest for the eyes (computer vision syndrome is on the upswing). The alternative is rapidly becoming unemployment in our computer dependent work environments so it’s really not an option. Maybe when you gaze at the computer for three hours then look up a focusing spasm occurs for 30 seconds and the blurred image causes your visual system to try and adapt (focus for the right distance). This mal-adaptation would cause myopia. Then again you could habitually focus to close or too far (normal is a little behind the object viewed). Probably it is something altogether different. Focusing on a flat plane when we are designed to focus in a 3D world could push the eye into changing. The tear film layer of the eye is crucial for clear vision and dry eyes could cause blurred vision. Working on a computer causes a decrease in blink rate and subsequent drying of the eye and degradation of the tear film layer. A poor tear film equals blurry vision and possibly Dry Eye Syndrome ( DES). Regardless, the result I believe, (with no real evidence to back it up other than what I see day to day and year to year), is that very few people  totally stabilize today at any age. Most show a very marked reduction in changes in their twenties, especially when they get out of school. A lot of optometrists refer “stable” as eyeglass correction changes 2 steps or less in a year. A few patients I see start to get better for no apparent reason. I have asked all the questions I can think of about lifestyle etc. and the only common factor I have ever found is invariably they are wearing their full distance correction, not under corrected like some Eye Doctors believe is beneficial. Please note that only a small subgroup of people wearing their full RX improve year to year. The eye has a built in self correcting mechanism called emmetropization which I believe starts working again in some people at a later age for unknown reasons. If we didn’t have that process there would really be a lot of very, very thick lenses! Also I see much less dramatic differences in prescriptions between the eyes when people wear their glasses full time. Occasionally people have the same prescription in both eyes and ask if it will stay that way-probably not but wearing the correct lens prescription will keep them much closer to each other. Statistically nearsightedness decreases a little in your 40’s due to changes in the lens in the eye. Later in life, the lens changes again as cataracts start to develop and nearsightedness increases. This is really nice for people that are farsighted since they notice improvements (at least for a while). People who are diabetic with poorly controlled blood sugar have prescription changes all over the board. Last but not least, patients ask if they can do anything to prevent their eyes from changing. The answer is—–Maybe-maybe not-or  definitely yes in the future. A prescription drug due out in the next few years may slow changes in childrens eyes. Orhtokeratology (also called corneal molding in some formats) may slow changes but this involves wearing rigid gas permeable lenses and sometimes comfort issues. One soft contact lens which is less “elastic” than others may slow changes. Aspheric soft contact lenses may have some potential in my opinion but there is no basis for this currently that I am aware of. One small study indicated bifocal soft contact lenses may also have some effect, again my guess is due to an aspheric effect on peripheral vision correction. We always recommend good ergonomics if only for the relief of eyestrain they offer: Look up every 15 minutes or so at something far away then close and back and alternate 10 times to break any focusing spasms. Get up every hour even if you only walk around the computer-this breaks the physical and visual posture. Use anti reflection coatings on your glasses prescription and have a separate computer lens prescription if you are presbyopic (need bifocals). An unpreserved artificial tear used 3-4x per day when doing a lot of near work could be helpful. Children who are esophoric (eyes that don’t turn in but have the tendency to turn in at near) may benefit from a multifocal prescription. I would think the same is true of adults but again I am not aware of any research. It probably will change again at some point in the future. Nutritional advice varies all over the place and probably has an effect- eat a healthy diet with lots of fruits and vegetable and little sugar is about as far as I can say at this time. And rest assured, your chances of going blind even though your vision seems to change every year is very, very low-and seeing your eye doctor every year for a dilated eye exam is great preventative care.

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