contact lens exam
Prosthetic Soft Lens Basics
DAVID KADING, OD, & JENNIFER L. SMYTHE, OD, MS, FAAO
The recent explosion in direct-to-consumer advertising
and the availability of cosmetic tinted contact lenses have generated interest in
our practice for using tinted lenses to mask ocular disfigurement. The goals of prosthetic lens
fitting vary from improving appearance to enhancing vision or visual comfort.
Prosthetic lenses require a systematic fitting approach with
additional testing. In some cases this falls under a therapeutic evaluation that
medical insurance may cover under CPT Code 92070, accompanied by a contact lens
"V" code and a diagnosis code to indicate medical necessity.
Pre-fitting Points of Discussion
The first step is to set realistic expectations. It's imperative
to elicit as much information from the patient as possible regarding both cosmetic
and visual goals.
When reviewing prosthetic lens options, explain that it may not
be possible to perfectly match the "good eye" in all situations and environments.
The lens performance and aesthetics are dependent upon lighting conditions, pupil
size and glare. As with any specialty lens, outlining the drawbacks and being realistic
about expectations prevents potential frustration or disappointment after the fitting
process has begun.
Add digital photography, corneal topography, and pupil and corneal/iris
diameter measurement to your normal contact lens exam. In the case of a disfigured
but seeing eye, you can use a detailed refraction and possibly a GP lens over-refraction
to determine the visual acuity potential.
You can piggyback a hyper-Dk GP lens over a prosthetic soft lens
to correct irregular astigmatism. Perform corneal topography or keratometry over
the soft lens and then select the GP lens parameters based on the curvature over
the prosthetic lens.
Figure 1. A prosthetic lens improved the appearance
of this disfigured eye.
Iris color varies dramatically with changes in lighting conditions,
head position and eye movement. Although it's difficult to perfectly match the
color of the good eye, a digital camera can aid in the process. Capture the following
images: Close-up shots of the affected eye, unaffected eye and the two eyes together,
plus a full-face photo. Take all of the images with and without a flash to simulate
bright and dim illumination.
Follow up and Fine-tuning
You can refine the color and fit after you allow the dispensed
lenses to equilibrate. To problem solve color variations, repeat the photography
protocol with the lenses on under varying light conditions with and without a flash.
You might consider prescribing an opaque cosmetic lens for the "good eye" to more
closely match the prosthetic lens color. In a light-eyed patient, the normal eye
may need a darker opaque lens to resemble the prosthetic lens.
A final tip is to prescribe non-AR coated polycarbonate spectacles
to wear with the contact lenses. These protect the eyes, and the glare from the
lens surface helps camouflage any irregularities in color or shape matching.
Dr. Kading completed a cornea
and contact lens residency at the Pacific University College of Optometry and is
now in private practice in Bellevue, Washington. Dr. Smythe is an associate professor
of optometry at Pacific University and is in private group practice in Beaverton,
Contact Lens Spectrum, Issue: October 2005