How Contact Lens Power and Prescription Differ

How Contact Lens Power and Prescription Differ

by Brian Chou, OD, FAAO, FSLS

  • February 15, 2023

A contact lens prescription includes several parameters including power. Lens power describes light-bending efficacy. It is just one part of a contact lens prescription.

Other elements of a contact lens prescription include material, diameter, and base curve. Custom scleral lenses have other complex specifications for sagittal vault, limbal clearance, and scleral landing zones. There is an art and science behind custom lens prescribing, and this is why an experienced and knowledgeable contact lens practitioner is important to your successful outcome.

To further elucidate, take for example the following two scleral lenses which share the exact same base curve of 6.37mm, power of -13.62D, and diameter of 16.5mm. It is obvious that despite these same three parameters, they are drastically different and not equivalent. Custom contact lenses often have other specifications which are more detailed than traditional parameters. Without all of these custom specifications, you will not receive the lens that your eye doctor intends for you. Your eye doctor controls the lens specifications and works with a custom lens laboratory to bring you a desirable outcome.

Power and prescription are not synonymous when it comes to contact lenses. Lens power can remain unchanged even though your contact lens prescription is different.


ReVision Optometry is a referral-based practice in San Diego providing scleral contact lens services for patients with keratoconus and other complex eye conditions. To schedule, request your examination online or call our office at 619.299.6064.