Why a contact lens prescription is different
Glasses sit a centimeter from the eye; a contact lens sits on it, so the power is different, and the lens must also match the cornea's curvature and diameter, move correctly with each blink, and suit the eye's tear film and oxygen needs. A contact lens prescription specifies the brand, base curve, diameter, power and replacement schedule, and it is valid only after the fit has been checked on the eye. That is what the contact lens exam adds to a standard exam.
What the exam involves
- A comprehensive eye exam, including the health of the cornea and the tear film, which decide whether lenses are advisable
- Corneal measurement: curvature by keratometry or topography, and diameter
- A discussion of how you will use lenses: all day, for sport, occasionally, with reading needs, with dry eyes
- Selection of lens type and material: daily disposable, two-week or monthly soft lenses, toric for astigmatism, multifocal for presbyopia, or rigid or specialty lenses where needed
- Trial lenses placed and assessed after settling: centration, movement, coverage and comfort
- Vision through the lenses, refined with an over-refraction
- Training in insertion, removal and care for new wearers
- A follow-up after a week or two of wear to confirm the fit and finalize the prescription
Annual contact lens exams
Contact lenses change the cornea's environment, reducing oxygen and altering the tear film, and problems develop quietly: new blood vessels growing into the cornea, surface staining, giant papillary conjunctivitis under the lid, or gland dysfunction. The yearly exam checks the cornea under magnification with the lens on and off, confirms the fit still suits the eye, updates the power, and reviews wearing habits and hygiene. It is also when a better lens, a newer material or a daily disposable is offered.
When standard lenses are not enough
If the cornea is irregular, the astigmatism high, the eyes dry, or previous lenses have failed, the exam moves into a specialty fitting with custom soft, rigid, hybrid or scleral lenses. And if you are tired of lenses altogether, the same visit can begin the conversation about LASIK, SMILE or the EVO ICL.
Is this right for your eyes?
Nothing on this page is a diagnosis. Whether this is the right choice for you is decided by a full examination at one of our 4 offices: Pasadena, Huntington Beach, Woodland Hills and Beverly Hills.
About this content: This page was written with the assistance of AI tools and reviewed for medical accuracy by Dr. Arbi Melikian, OD. It is general information, not medical advice, and does not replace an eye examination. Individual results vary. Read our medical disclaimer.
