EVALUATING POTENTIAL SPECIALTY LENS PATIENTS
STEPHANIE L. WOO, OD
Fitting a patient into specialty contact lenses can be a rewarding experience. But what happens when the vision is not what you or the patient had expected? After fitting many different eye diseases, I’ve learned that specialty contact lenses are not for everyone. Through challenging cases, I’ve discovered my own screening process that works well for my practice to identify good and poor candidates for specialty contact lenses.
In my office, every patient who is referred for specialty contact lenses has a consultation before any lenses are even attempted. I used to include only topography, pachymetry, a vision check, and a quick slit lamp assessment; now, I also include specular microscopy to check endothelial health as well as optical coherence tomography (OCT) evaluation to check the health of the macula. The reason for this is that even with the best-fitting contact lenses, patients who have retinal diseases will have limited vision.
A 67-year-old white male was referred to me for a contact lens fitting for his irregular cornea OD. His referring ophthalmologist had diagnosed him with dry macular degeneration OD and wet macular degeneration OS. Best-corrected visual acuity was 20/200 OD and 20/hand motion OS. He had seen a corneal specialist about a month prior who had fit him with a diagnostic GP lens OD, through which he achieved 20/50 vision. After reviewing his topography, pachymetry, slit lamp exam, and notes from the corneal specialist and referring ophthalmologist, I was confident that a specialty contact lens would help improve his vision.
After discussing all options, the patient opted for a molded scleral lens OD. Though the price was higher compared to a traditional scleral lens, he wanted a premium product. We obtained an impression of his ocular surface, sent it to the lab, and we received the molded scleral lens.
Upon application, he could still see only 20/200. Even over-refraction would not improve his vision. I dilated his eye, performed OCT on the macula, and discovered that he had progressed from dry macular degeneration to wet macular degeneration without knowing (Figure 1).
Figure 1. Wet macular degeneration causing severely limited vision OD.
I had to explain to him that his vision could not be improved. As you can imagine, he was extremely upset that he had spent so much time and money at my clinic. In that moment, I realized that every patient needed a more in-depth consultation before proceeding with a specialty lens fit.
Post-radial keratotomy (RK) patients may also be difficult. Sometimes the scarring from the RK surgery extends all the way into the pupil zone, creating an extra-small optic zone. This alone can affect their visual outcome. Another issue is that if the posterior cornea is too irregular, even the best contact lens will not resolve the posterior float irregularities (Dr. Christine Sindt explained the challenging nature of the posterior corneas of RK patients to me).
I do not have access to an instrument to evaluate the posterior cornea, so now I need to be extra cautious when setting visual expectations with these patients. There is no way to know how their vision will respond to a specialty contact lens without a diagnostic fitting.
Learn from My Mistakes
Consider performing a complete eye exam or at least a more detailed consultation on all potential specialty contact lens candidates to ensure that you and the patient discuss realistic visual acuity outcomes and prevent unpleasant surprises. CLS
Dr. Woo currently practices at Havasu Eye Center in Lake Havasu, AZ. She is also the treasurer for the Scleral Lens Education Society and is an Advisory Board member for the GPLI. She is a consultant or advisor to Alcon, Blanchard, Bio-Tissue, B+L, Essilor, and X-Cel.