Prescribing for Presbyopia
How to Choose Between Soft and GP Lenses
BY DOUGLAS P. BENOIT, OD, FAAO
Aquestion often asked is: “Should I use a soft lens or a GP lens on this patient?” The type of lens selected should be based on individual patients’ visual needs, their refractive error, and their physiologic (and physical) status. Add a little experience with various multifocal designs, and the proper choice becomes clear.
First, determine whether patients are current lens wearers. If so, what type of lens are they wearing, and are they happy with their vision at distance? If their only complaint is with near vision, you could stay with their current material in a presbyopic lens design.
But what if they are not happy with their distance vision? First, evaluate the vision (over-refract to improve distance vision, incorporate add to improve the near vision) and the fit of the current lenses. Next, remove the lenses and perform a careful refraction. Perform a slit lamp examination looking at the lids, lashes, meibomian glands, tear film status, bulbar and tarsal conjunctiva (including the lid wiper zone), cornea, iris (noting horizontal visible iris diameter and pupil size), and the crystalline lens. Determine keratometry values and/or perform topography. Lastly, do a fundus examination to be sure that their distance complaint is not retinal in nature.
If everything is in order and the new refraction provides good vision, it is time to choose a new lens. These fictional examples will help illustrate this process.
Case #1: The Happy Patient Jane, 42, currently wears a monthly replacement spherical soft lens. Her distance vision is 20/20, but near is only 20/50. She works in insurance and does a lot of computer-related tasks. She also is an avid cyclist and hiker.
Jane expresses a desire to change to a daily disposable lens. Her ocular health is normal, and her tear quality and quantity seem good. She is a –3.00D myope with a +1.25D add OD and OS. Her keratometric readings are 42.50/43.00 @ 90 OD and OS. She is an excellent candidate for a daily disposable multifocal. Because Jane does a lot of outdoor activities, a center-distance design was picked. She achieved 20/20 vision at distance and near in each eye and adapted in just a few days.
Case #2: The Not-So-Happy Patient Jean, 42, currently wears a monthly replacement spherical soft lens. Her vision is 20/25, and she complains of fluctuating vision. Keratometry over the lenses shows distortion with the blink. Near vision is 20/50. She is a receptionist and does a fair amount of computer work. She gardens and reads in her spare time. Her ocular health and tear film are unremarkable. Her refraction is –3.00 –0.75 x 180 with an add of +1.25D OD and OS. Her Ks are 42.50/43.50 @ 90 OD and OS.
Jean is a good candidate for either a soft toric multifocal or a GP multifocal. There is only one frequent replacement (monthly) soft toric multifocal on the market. But, there are a number of custom offerings from independent labs. A GP multifocal would also work, and as it turned out, Jean had worn GP lenses until her last practitioner switched her to the soft lenses. A bi-aspheric GP design provided 20/20 vision at all distances. Comfort was excellent, and Jean now regularly refers patients to the office.
These examples show that success is achievable with the proper approach and a little experience with some of the many designs that are available. CLS
Dr. Benoit is the senior optometrist with Concord Eye Center, a multi-subspecialty ophthalmology group in Concord, NH. He is a Diplomate of the American Academy of Optometry’s Section on Cornea, Contact Lenses and Refractive Technologies, currently the Special Advisor for the section. Dr. Benoit is a Distinguished Practitioner and Fellow in the National Academies of Practice-Optometry Section and is a Diplomate of the American Board of Optometry. He is also on the Advisory Board of the GPLI and is the 2016 GPLI Practitioner of the Year. Dr. Benoit is a consultant to, and clinical investigator for, Alcon.