How Eye Exams for Contact Lens Are Different from an Eyeglass Exam

Dr. Kisling Contact Lenses Leave a Comment

There is a difference between eye exams for contact lenses versus eye exams for eyeglass wearers. When making an appointment for an eye exam, express your desires for either eyeglasses or contact lenses.  Typically, people already wearing eyeglasses schedule appointments to switch over to contact lenses. The motivation may be cosmetic, better peripheral vision, or for athletics. Those who have never worn glasses and find out during a routine eye exam that they need corrective lenses can discuss their options with the eye doctor. Then they can choose to either proceed with a contact lens exam and fitting or come back at a later date after careful consideration of the options that will best fit their lifestyle.

An exam for eyeglasses consists of a series of tests performed by the eye doctor and their technician. A computer aided analysis is performed by the optometrist by asking you to stare at a certain point in an instrument. By doing this, the doctor is determining how the light wave is altered as it bounces off the inside of your eye. This gives the doctor a good starting point for the strength of prescription you need. A Refraction test is also performed with a Phoropter where you will look through a mask like device at a series of letters.The doctor flips lenses in the mask and asks when it looks the most clear. This is the dreaded point of commitment to one or two. Since it is a forced choice test (that is a psychological term for being restrained in the exam chair until you decide on two horrible, blurry options) many patients feel uncomfortable with deciding on an answer. While this may feel like a day in the voting booth, you need not worry. A vision exam never relies on a single answer. Also, the lenses may change even though the number stays the same. Occasionally patients worry that it was clearer in a previous view, or even in between changing views. Since you can’t see the exam from the eye doctors point of view, you can’t see the logic in what may appear to be faulty testing. Don’t be concerned, repeated testing sequences assure that your answers are reliable before a prescriptions is finalized. The result is a clear determination of whether you are nearsighted or farsighted, whether you have astigmatism and whether presbyopia is present.  Last, the doctor will perform a slit lamp exam and examine the inside of your eye to look for eye diseases such as glaucoma, cataracts and macular degeneration.

During a contact lens exam, the cornea surface is the center of the exam.  The doctor runs tests to assess the cornea to get the right fit for the contact lenses.  An instrument measures surface and curvature of the eye. It works like a digital camera that takes pictures of the eye and creates mathematical depictions of the curvature of the cornea surface.  This gives the doctor the sizing for the contact lens.  A microscope is used to determine the health of your cornea and your  pupils may need to be measured if you are being fit for bifocal contact lenses.Your tears may be measured with a tear film evaluation to determine the amount of eye moisture in the eye as well as a fluorescent dye that is placed in the eye to see the quantity of tears present and any cellular compromise to the cornea. Careful attention is paid toward analyzing the eyelid margins and the clear tissue covering the white part of the eyes and under the eyelids for any signs of eye disease or problems that may interfere with successful contact lens wear. After testing, the doctor will select a contact lens that best matches your eye. This lens is usually fit for a trial period to make sure your eyes are adapting in a healthy manner. More complicated contact lens fittings may require several visits to find the optimum lens for your eyes. In cases where bifocal contact lenses or contact lenses for eye conditions causing  irregular astigmatism this may take several months to reach a finalized prescription.

In its important to remember that contact lenses are never a replacement for eyeglasses. I have seen numerous cases where patients wearing contact lenses did not have a pair of prescription eyeglasses and acquired an infection, a scratched eye, or a particle of metal lodge in the cornea tissue on the front of the eye. Having no backup option when away on a trip they continue to wear thier lenses and the end result can be scarring and eye damage. Always having a backup pair of spectacles is priceless in preserving your eye health.. This is even more important with teens and children who tend to not complain until their eyes are already in an advanced state of compromise. Because they are more concerned with appearance at certain ages, they are much more reluctant to understand the necessity of eyeglasses as an emergency preventative health device.

Contact lenses are a medical device controlled by the Food and Drug Administration and should be given the care an respect as any other medical device. Part of this care is an annual eye exam that assures your eyes are continuing to have a healthy adaption to this marvel of technology, first envisioned by Leonardo da Vinci in the 16th century.

Leave a Reply

Your email address will not be published. Required fields are marked *