Fitting a Range of Presbyopes With GP Multifocal Lenses
BY EDWARD S. BENNETT, OD, MSED, & STEPHEN P. BYRNES, OD
Presbyopic patients represent a great area of potential growth in the contact lens industry, notably because of new advances in materials and designs for these patients. GP lens designs are especially promising because advancements in manufacturing technology result in better optical quality and visual acuity at all distances. In particular, the availability of multifocal designs in high add powers is becoming the rule rather than the exception.
Presenting the Options
It's important to be proactive with every presbyopic patient by discussing multifocal contact lenses. If a patient expresses interest, it's important to present all contact lens options including over-readers, monovision and soft and GP multifocal lenses. Although we both prefer GP multifocals, realistically some patients will opt for monovision. It's important to provide such patients with spectacles to wear over their lenses for critical distance tasks, notably night driving.
Determining patients' primary goals from multifocal contact lenses (such as good vision while driving and at the computer; good vision for reading and at the computer, etc.) and attempting to meet them is important. You should also indicate that occasional over-spectacle wear may be desired, possibly during night driving and/or reading small print in dim illumination.
Ease of Fitting
Many patients find that GP multifocal lenses are more comfortable initially compared to spherical GPs. And they may lend themselves well to empirical fitting, which allows patients to experience more natural vision at all distances during their first experience with GP multifocal lenses.
Encourage patients to walk around the office and perform desired visual tasks such as reading a magazine, looking at a computer screen and viewing off at a distance. If your office is located in a commercial setting, patients can walk to a neighboring store. Loose trial lenses or flipper bars can help you fine-tune the power, preferably performed binocularly.
High Add Designs
Almost every laboratory now has GP multifocal lenses available in high add powers. Examples of such lenses include the Renovation Multifocal (Art Optical) and the Essential CSA (Blanchard).
The Renovation Multifocal has a center-distance intermediate section ranging from 3.5mm to 4.25mm and an annular near section. It's a front-surface aspheric, back-surface sphere design, although it is available with back-surface asphericity (Renovation-e) if necessary to increase the effective add.
The Essential CSA is a back-surface aspheric design. Additional add power can be placed on the front surface in an annular ring that surrounds a center-distance zone ranging from 4.0mm to 4.6mm.
For both designs to be successful for moderate-to-high add powers, the lenses need to translate, at minimum, 1mm to 2mm with downward gaze.
Multifocal resources are available through the GP Lens Institute (GPLI) Web site at www.gpli.info. These include a comprehensive educational kit titled "Rx for Success," laminated cards and brochures, a narrated PowerPoint presentation and cases in the "GP Lens Case Grand Rounds Troubleshooting Guide." CLS
Some of this information was obtained from the September GPLI online symposium on GP Bifocal and Multifocal Lens Correction.
Dr. Bennett is an associate professor of optometry at the University of Missouri-St. Louis and is executive director of the GP Lens Institute. Dr. Byrnes maintains a primary eyecare private practice specializing in contact lenses in Londonderry, NH. He is also an educational consultant to schools and colleges of optometry for Bausch & Lomb and Polymer Technology.