Contact Lenses

Examination
You need to have a recent vision exam, which you can get through the Casey Eye Institute's Casey Ophthalmic Associates (COA) clinic or with your regular eye doctor. Generally this exam should include dilation, in which special eye drops are used to enlarge the pupils so the eye doctor can see inside the eyes to evaluate the eye health. The standard dilation can cause your vision to be blurry for several hours. Most, but not all people are able to safely drive themselves home with dilated eyes. You won't know how blurry your vision will be until after your eyes are dilated, so it's safest to have a ride arranged.


Diagnosis
The doctor will tell you if you need vision correction. You may be myopic (nearsighted), hyperopic (farsighted), astigmatic, presbyopic, or anisometropic. Contact lenses can be used to correct all of these conditions for most people.


Glasses Prescription
You can get a glasses prescription at your vision exam. This is used as the starting point for your contact lens prescription. The shape of the cornea (front of eye) is also an important measurement.


Contact Lens Fitting
The contact lens specialist will use your glasses prescription as a starting point to determine what type of contact lenses
are best for your vision. You may be fitted with disposable, planned replacement, or conventional, spherical or toric, soft or rigid gas permeable (RGP), monovision, bifocal, or a combination of glasses and contacts. For the fitting, the contact lens specialist will determine the appropriate lenses and either pull them from a selection of diagnostic lenses on site or will order custom lenses. Many patients can get lenses on the day of the initial exam. The lenses are placed on your eyes and the contact lens specialist will evaluate the health of the fit, the clarity of vision, and the comfort. Generally, you then try the lenses in "real life" for a week or more to make sure everything is good, and then come back for a follow-up visit (wearing your lenses), at which the contact lens specialist will again evaluate the lenses for a healthy fit. Be sure to put the lenses in an hour or two prior to the visit, so the lenses are warmed up to body temperature and are saturated with your tears. If you are a new wearer of contact lenses, we will teach you how to insert, remove, and care for your lenses before we send you home with any lenses.


Contact Lens Prescription
The contact lens prescription cannot be written until after the fitting process is completed. Since the contacts sit on the eyes, the contact lens specialist must evaluate the health and clarity of the fit with the lenses on the eyes. The first contact lens tried is the lens that should work based on the glasses prescription and shape of the cornea (front of eye). The final contact lens that the prescription is written for is the one that worked well for you in "real life." Sometimes this is the same lens, but not always. More complicated prescriptions may take several visits and various diagnostic lenses before the prescription is finalized.


Why the glasses prescription is not the same as the contact lens prescription
Your glasses prescription is the starting place in determining the correct contact lens prescription, but the two prescriptions are not the same. You can't use a contact lens prescription to get glasses, and you can't use a glasses prescription to get contact lenses. The contact lenses actually touch the eyes, so they must be precisely fitted and the fit must be evaluated with the lenses on the eyes to be assured that the lenses are a healthy fit. The contact lens prescription can not be finalized until the fit is determined to be healthy.

The numbers on the glasses prescription and contact lens prescription may look very different, especially if you have a big prescription. This is simply due to optical mathematics.


Follow-up Care
When you wear contact lenses, you need to have an eye exam at least annually (or more often if recommended by your doctor). This is because, unlike glasses, contact lenses sit directly on the eye, and may affect the health of your eyes.





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