Prescribing for Presbyopia
Consider Bifocal GPs for Early Presbyopes
BY CRAIG W. NORMAN, FCLSA
Recently I traveled to the University of Houston, College of Optometry where I was hosted by Dr. Judith Perrigin and asked to provide a lecture to her students on GP presbyopic contact lens systems. This was followed by a bifocal/multifocal workshop with her students that involved a dozen or so patients in some phase of the fitting or wearing process with GP lenses as their presbyopic correction.
Contrary to the myth that today's young eyecare practitioners aren't interested in contact lenses—especially GP lenses—the students enthusiastically embraced the challenge of fitting, evaluating, and refitting patients who were early and more mature presbyopes and whose vision correction needs included all types of spectacle prescriptions.
Like most people who are fortunate enough to be involved in teaching, I usually am able to learn one or two key pearls as I'm lecturing while hopefully imparting some of my own experiences and knowledge at the same time. On that particular evening, what struck me as odd was how many of these workshop patients were wearing bifocal (rather than multifocal) GP lenses; especially in patients who were early presbyopes and had add powers from 1.00D to 1.75D. Fitting bifocals or multifocals early has long been a strategy in soft lens use, but this was the first time I had witnessed this with GP bifocals.
For most early presbyopic GP lens candidates, I usually begin by recommending multifocal designs, then consider a segmented bifocal when a higher add power is indicated and not achievable with a multifocal. This strategy has worked well, although occasionally there is an adjustment to a segmented, weighted design when the switch is made.
Figure 1. Early presbyopes who have difficulty with intermediate vision in a GP bifocal may succeed with Truform Optics' Llevations Multifocal Lens Design.
A Different Philosophy for Presbyopic GP Designs
Dr. Perrigin's philosophy is a little different. She maintains that fitting bifocal GP lenses earlier makes more sense for three reasons. First, it allows patients to adapt to bifocal vision while still having enough accommodative power to ease the initial visual adaption. Second, patients adapt to the movement of the lens and additional thickness of a prism-ballasted modality at the same time. Third—and probably the most important of them all—as patients age and their reading requirements change, all that's necessary is a simple update in add power, with no other modification needed to the lens design.
One of the "urban myths" of segmented GP bifocal lenses is that patients cannot use this design at the computer or intermediate reading level. My experience is that while this might be an issue for some patients, it usually isn't a major one.
Dr. Perrigin's philosophy is helpful here also. Early presbyopes usually don't have as much issue at the intermediate level; if they do become symptomatic, then changing from a bifocal to a similar GP multifocal—such as switching from the Solitaire bifocal (TruForm Optics) to Tru-Form's trifocal Llevations Thin Multifocal (Figure 1)—is an easy process.
Thanks, Judy—this was a wonderful tip. CLS
Craig Norman is director of the Contact Lens Section at the South Bend Clinic in South Bend, Indiana. He is a fellow of the Contact Lens Society of America and is an advisor to the GP Lens Institute. He is also a consultant to B&L. You can reach him at firstname.lastname@example.org.