Is there a problem?

Well -- yes. After a general eye examination, patients often ask their optometrist for a contact lens prescription from the general examination and having it filled at a local ”contact lens outlet” for an advertised cut-rate cost which may sound appealing. But most patients are unaware that, to achieve the best possible result, there must be active involvement of the optometrist in examining the eyes, fitting the lenses, professional decision making, and care for a period of months before a contact lens prescription is finalized and ready for the option of release.

Verbally communicating to patients why we cannot write a contact lens prescription from the spectacle refraction is time consuming for doctors and staff members. Unfortunately, these explanations are often interpreted by the patient as a defensive and uncooperative attitude of the doctor.

Recognizing this, Dr. Christopher Snyder O.D., M. Sc., at the School of Optometry, University of Alabama has devised a simple, one-page handout for patients to educate them and clear up any misconceptions on their part before they think to ask “the contact lens prescription question.” Patients are asked to read the handout before their general eye examination. The handout is reproduced here as it appeared in the March 1989 issue of the Journal of the American Optometric Association.

What is a contact lens prescription?

A contact lens prescription is not the same as a prescription for glasses! A contact lens prescription includes specifications not only for the optical correction of the eye, but also for the lens material and design features so the lenses fit safely and properly on the eyes. The ultimate goal is for the contact lens wearer to see well, be comfortable, and not harm his or her eyes by wearing the lenses.

Let us show you an example of a patient’s prescription for a spectacle lens:  

-4.50 -0.50 X 178

Now an example of this same patient’s possible prescription for a gas permeable contact lens:

-3.75 D.S.; 9.2/7.6; 7.42 mm; 8.5/0; 11/0.2; Paraperm 02+; blue; dot

And now an example of this same patients’ prescription for a soft contact lens:

-4.00 D.S.; 8.6 mm; 13.8; CibaSoft; Visitint

These examples are not to overwhelm you but to demonstrate that a spectacle prescription and a contact lens prescription can have few, if any, similarities. The important differences are determined through careful and special measurements and evaluation of the eyes and contact lenses. Such tests as K readings (curvature of cornea) and the other should be performed by the practitioner fitting the lenses.

A thorough diagnostic fitting with contact lenses coupled with several progress check visits to determine that the prescribed lenses are the optimum for the eyes, allows us to finalize a contact lens prescription. With some patients, lens design modifications may be necessary before the practitioner can arrive at a final contact lens prescription

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