- Dr. Paul Karpecki and Dr. Richard Durocher
As recently as five years ago, monovision was the "standard of care" for addressing the vision problems of presbyopes. Although monovision requires the patient to see at a distance in one eye and close up in the other - hindering depth perception and mid-range vision - it was considered an acceptable tradeoff when the alternative was bifocal glasses.
Some eye care professionals today continue to choose monovision when fitting early presbyopes (+1.50D or less) because the lens adaptation is relatively easy and the results are generally acceptable to patients. But the unavoidable drawback of monovision is its lack of binocular summation, which severely limits up-close activities that require hand-eye coordination.
While bifocal contact lenses have been around for several years, only about two out of 10 patients1 could wear them successfully. However, that success rate has improved dramatically with the recent development of new materials and designs. There is no single, multifocal contact lens option that is right for all presbyopes, but the expanded availability of lens choices today makes fitting multifocal designs easier than ever before and patients are ready for something other than monovision.
Ohio State Study of Multifocal Contact Lenses vs. Monovision
In fact a recent study2 conducted at Ohio State University College of Optometry pitted the industry-leading multifocal design (Bausch + Lomb SofLens Multi-Focal) against traditional monovision. The investigative protocol was a randomized two-month crossover study of 38 presbyopic patients with the mutlifocal lenses and monovision lenses worn for one month each. The mean age of participants was 50.1 +/- 4.7 years with an actual age range of 41 - 64. The distance refractive error mean for each eye was OD -0.74 +/- 1.96D with an actual range of -4.63D to +3.00D and OS -0.81 +/- 2.10D with an actual range of -6.50D to +2.75 D.
The key findings of this study include:
- Three out of four patients reported that they preferred mutlifocal contact lenses to monovision.
- There was a significant association between near, low-contrast visual acuity and the preferred lens modality.
- Three times more multifocal patients than monovision patients were still wearing their chosen contact lenses at least three days a week six-12 months after completing the study.
- None of the monovision patients considered contact lenses to be their preferred form of vision correction.
I think these results are telling in that there is a statistically significant preference for a proven multifocal contact lens design. While the study was conducted using the Bausch + Lomb SofLens Multi-Focal lens, even that lens has been enhanced with the Bausch + Lomb PureVision material. PureVision Multi-Focal lenses use the same progressive, center-near vision design with advanced aspheric optics and is made from a silicone hydrogel material. This is an exciting development for any doctor that wants to provide presbyopes with the highest quality of vision in an even healthier and comfortable lens material.
In the past when fitting new presbyopes, the first lens I have always tried is the Bausch + Lomb SofLens Multi-Focal. Now I will reach for PureVision Multi-Focal. While both lenses have the same unique design that provides impressive near, far and in-between vision, I like the prospect of offering patients a higher Dk that comes with a silicone hydrogel material such as balafilcon A which is used in all PureVision lenses.
The PureVision Multi-Focal Difference
According to the company, the PureVision Multi-Focal is cast-molded in balafilcon A, which is a highly breathable lens that is durable, resists protein deposits and dehydrates less than most hydrogel materials. Beyond the lens material the unique design of PureVision Multi-Focal adds to the patient's comfort with its patented rounded edge design, which helps reduce lens awareness and its patented wide-intermediate-power profile allows for incremental power variance across the entire optic zone for clear, crisp vision at all distances.
1 The Eye Care Revolution. Robert Abel, MD. p. 59. 1999
2 Subjective and Objective Performance of the Bausch + Lomb SofLens Multifocal and Monovision.Richdale, Kathryn, OD, MS. Ohio State UniversityCollege of Optometry. Randomized two-month crossover study of 38 presbyopic patients. 2005.