prescribing for presbyopia
Change Breeds Success With Bifocal Soft Lenses
BY THOMAS G. QUINN, OD, MS, FAAO
Embrace change and you will experience soft bifocal contact lens fitting success. Implement these changes to help you and your presbyopic patients become winners.
Settle Down, Now
We've heard it for years. Contact lens manufacturers have always recommended that we allow lenses to settle for 10 to 15 minutes before assessment. How many of us actually heed this advice?
When fitting bifocal soft lenses, the wait is well worth it. The patient's vision improves over this time (usually the near vision clears sooner than the distance vision), and the patient can develop a "scouting report" for you. Send him out into the reception area and encourage him to explore his visual world. When he returns to the exam room, ask a very open question such as, "How are you seeing?" If he reports a problem, you know immediately where to focus your energy. In essence, the patient does your work for you. Give him the time to do it.
Virtually all popular bifocal soft lenses utilize a simultaneous vision design. Both distance and near light enter the pupil at the same time. The brain then pays attention to the light it needs (such as distance light rays while driving). Pupil size influences the amount of light exposed to the retina. When measuring acuity and performing over-refractions, try to simulate the lighting conditions the patient operates under most of the time. This usually means turning up the lights in the exam room.
As the bifocal power increases, it is more likely to interfere with distance vision. High add patients often need a low add on the dominant eye to maintain clear distance vision. Keep the high add on the non-dominant eye to provide adequate near vision.
See in Stereo
Test vision under binocular conditions. This not only improves visual performance, it provides a truer measurement of how the patient sees under normal, everyday conditions. I explain to patients that when it comes to bifocal soft lenses, two eyes are much better than one. This helps patients overcome the tendency to compare vision between the eyes, which is particularly problematic when employing unequal adds.
Over-refract with Flippers
Over-refract bifocal lens wearers using loose lenses, conveniently available in flippers, which have minus and plus lenses of the same power mounted on opposites sides of the flipper holder. Flipper lenses allow us to easily demonstrate changes with minimal disruption to the normal visual environment. Plus you don't have to worry about pupil size effects and proximal accommodation as with a phoroptor. Besides, flippers are easier.
Flippers of ±0.25D and ±0.50D are a must. I also have a ±1.00D pair. I frequently hold the +1.00D over the opposing eye when testing its partner. I find the patient is less likely to "eat the minus" compared to using an occluder over the opposing eye.
Most of these techniques attempt to create an environment similar to what patients experience during their day-to-day activities. It's more "real world" for the patient, and it creates a new world for us...a world of success with bifocal soft lenses.
Dr. Quinn is in group practice in Athens, Ohio, and has served as a faculty member at The Ohio State University College of Optometry.