Myths About GP Multifocals
Numerous misperceptions exist about GP multifocal designs that are worthy of discussion. While these misperceptions are understandable, to experienced fitters they're simply not true.
1. GP Multifocals Don't Work: Monovision is Better. In comparison studies vs. monovision, Kirschen et al (1999), Johnson et al (presented at CLAO, 2000) and Rajagopalan et al (2006) have concluded that GP and soft multifocal lenses resulted in greater success than did monovision. In particular, the Rajagopalan study found that the GP multifocal wearers exhibited significantly better visual performance than did soft multifocal and monovision wearers.
2. GP Multifocals are Uncomfortable. For both aspheric multifocal and segmented designs to succeed, little movement must occur with the blink. For that reason, as I reported in my February 2005 column "Researching GP Multifocals," GP multifocals are often more initially comfortable than are spherical designs.
3. GP Multifocal Lens Designs are Too Much Hassle. A survey of the 50-member Advisory Committee of the GP Lens Institute reported that on average it takes only three fits with any one GP lens design to reach a comfort level fitting that design. Aspheric multifocal lens designs, in particular, are quite simple to fit. The material is often standard, as is every lens parameter but power, base curve and overall diameter. The lengthy fitting guides of the past now often consist of a one-page fitting nomogram.
4. GP Multifocals Provide Good Vision at Only One Distance. With newer GP multifocal designs, achieving good vision at all distances is definitely possible and often achieved. For patients who have an intermediate demand, first determine their primary visual goals. If distance and intermediate are most important for their needs, your goal is to satisfy their vision at those distances.
5. Patients Will Need Supplemental Glasses. This should be a requirement for monovision wearers, especially for driving at night. However, only a small percentage of GP multifocal wearers require supplemental glasses for detailed near work or night driving.
6. You Don't Need Segmented, Translating Designs in 2007. A small but significant number of patients simply refuse to accept any compromise at distance or near (or both). These individuals are perfect for segmented designs. Determining seg line position and adequate translation with downward gaze are keys for a successful fit with these designs.
7. I Can't Find Resources to Help Me Fit and Troubleshoot GP Multifocal Designs. The best resource by far is your CLMA laboratory consultants. They can also provide diagnostic sets, recommended patient selection pearls, etc.
The "Manual of Gas Permeable Contact Lenses" from www.elsevier.com and co-authored with Milton Hom, OD, FAAO, is a useful reference as is "Pinpoint Success with GP Multifocals"(CLS October 2003), by Robert Davis, OD, FAAO.
The GP Lens Institute (www.gpli.info) has a comprehensive GP practitioner, staff and patient training module titled "Rx for Success." In addition, a 54-case online troubleshooting book including 10 multifocal cases will be available in the first quarter of 2007 and an interactive "Click N' Fit" program will be available later in the year.
The Simple Truth
GP multifocals represent one of the fastest growing segments of the contact lens industry . . . and that's no myth.
For references, please visit www.clspectrum.com/references.asp and click on document #135.
Dr. Bennett is an associate professor of optometry at the University of Missouri-St. Louis and is executive director of the GP Lens Institute.