Contact Lens Business
Mastering Multifocals
When they work for your patients, they work for your practice.

BY PETER R. KASTL, M.D., PH.D.

Thanks to the "graying of America," elderly patients who need some sort of bifocal correction now constitute 40% of the vision care market. However, only 1% to 2% of them currently wear multifocal contact lenses. Yet multifocal contact lenses have some significant advantages over the alternatives:

• Wearing spectacles is sort of an "advertisement" of advancing age.
• Wearing reading glasses over distance contact lenses can provide excellent vision, but you still have to wear (and keep track of) a pair of glasses.
• Monovision contact lenses work well most of the time, but night vision -- especially when driving -- can be compromised.

Of course, multifocal contact lenses also have potential disadvantages:

• Soft multifocal lenses focus multiple refractions onto the retina simultaneously; the patient's brain must pay attention to the distance it wants to see. This type of optic system tends to make vision a little blurry at all distances.
• Rigid gas permeable (RGP) bifocal lenses usually have a distance segment at the top and a near segment at the bottom; prism ballast keeps the lens in proper orientation. The lens "translates" (moves up and down) so that it works like a bifocal spectacle lens. These lenses tend to be thick, making them less comfortable than standard RGP lenses, and the bifocal line sometimes bisects the pupil, causing double vision.

Despite these disadvantages, multifocal contact lenses work well in many circumstances, and patients may be happy to avoid the alternatives.

STRATEGIES FOR SUCCESS

When fitting these lenses:

Only offer them to the right patients. Regardless of the type of lens or fitting method you use, if you attempt to fit a poor candidate for these lenses, you'll never succeed.

"Good" patients for multifocal lens fitting include:

• new presbyopes already wearing RGP lenses; they'll readily adapt to wearing RGP multifocals
• presbyopes who have to wear bifocal spectacles, such as hyperopes and high myopes
• patients who are already wearing contact lenses and hate having to wear reading glasses.

"Bad" patients to fit with multifocal lenses include:

• low myopes or emmetropes. These patients can already see well with the unaided eye, either near or far. Multifocal contact lenses may distort the previously unaided distance vision.
• patients with previous contact lens failure for any reason
• picky patients, who usually aren't willing to make compromises.

Use loose lenses (not the phoropter) to refine visual acuity. After refracting for distance, place lenses with slightly different prescriptions on the eyes until distance vision is satisfactory. Use the same technique for near vision.

When measuring distance acuity with soft multifocal lenses, go only as far as 20/25. Never show the 20/20 line to the patient. Usually patients don't see it very well -- an artifact of the simultaneous vision system -- which can make them believe the lenses aren't working. (This isn't usually a problem with RGPs.)

Make sure patients are prepared to accept some trade-offs. You may want to find a polite way to remind them that they're not 20 years old any more.

Expect multifocal lenses to work better for patients in their 40s than in their 50s. By age 50, many patients need trifocals, which aren't available in RGP segmented lenses. Soft multifocal lenses work OK for trifocal distances, but patients in their 50s may require more near power than manufacturers can currently provide in these lens formats.

Charge more for a multifocal contact lens fit. At Tulane, we charge 50% more for a difficult fitting than for a standard contact lens fitting.

Dr. Kastl is professor of ophthalmology and adjunct professor of biochemistry at Tulane University School of Medicine in New Orleans, La. He specializes in cataract, refractive, and corneal surgery, and is an expert in contact lens technology and fitting. He is president-elect of the Contact Lens Association of Ophthalmologists (CLAO) for the year 2002.