Passing the Torch from Monovision to Multifocals
BY WALTER S. RAMSEY, OD, FAAO
Presbyopia is a daily challenge for many of the 75 million baby boomers who seek an active lifestyle and young-at-heart mentality. As recently as five years ago, the best answer to address the vision problems of presbyopes was monovision. Seeing at distance in one eye and at near in the other was acceptable when the best alternative was bifocal eyeglasses. But the freedom monovision afforded came at a price, yielding poor depth perception and mid-range vision.
Some practitioners still choose monovision first when fitting early presbyopes because lens adaptation is relatively easy and patients find the results acceptable.
Monovision's Achilles' Heel
An unavoidable drawback of monovision is its lack of binocular summation. Its very nature severely limits the full enjoyment of near activities that require hand-eye coordination, such as sewing, tying flies for fishing, needlepoint or building models.
Monovision can also hinder on-the-go baby boomers who may play tennis or golf, not to mention the legitimate safety issues that may result from reduced night vision with monovision.
Multifocals Come of Age
While bifocal contact lenses have existed for years, only about two out of 10 patients could initially wear them successfully. But new materials and designs have greatly improved this success rate.
Although no single, multifocal lens panacea for all presbyopes currently exists, the array of available lens choices makes fitting multifocals easier than ever.
My Multifocal Lens of Choice
When fitting new presbyopes, the first lens I try is the Bausch & Lomb SofLens Multi-Focal. According to the company, the SofLens Multi-Focal is cast-molded in polymacon, a Group I, low-water content (38 percent), non-ionic polymer. The lens also has an aspheric, center-near add zone, which B&L says provides smoother transitions for near, far and intermediate vision. Its patented Natra-Sight Optics allow for incremental power variance across the entire optic zone.
The SofLens Multi-Focal's patented rounded-edge design helps reduce lens awareness to further improve patient comfort.
Fitting This Design
You can improve patient success by discussing realistic expectations before applying the lenses, because some visual compromise is almost always a reality.
Cylinders above 1.00D, especially bilaterally, may pose an obstacle to a successful fit. K readings above 45.00 diopters usually require the steeper SofLens Multi-Focal base curve to avoid edge buckle, which can affect vision and comfort. For early presbyopes, try to obtain maximum plus with the distant prescription instead of increased add.
You may also succeed with modified monovision. If the patient does a great deal of near work, then it's best to increase the plus in his dominant eye. If the patient uses distance vision most of the time, then use his non-dominant eye for maximum near correction.
When refitting patients into this lens, remember to compare acuities with their old contact lenses, not with their eyeglasses.
The Goal: Best Vision Possible
The obvious goal for any practitioner is to provide patients with the best vision possible. A decade ago, monovision was the best alternative to achieve that eyeglasses-free goal for presbyopes. Today, thanks to the next genera tion of multifocal lens designs and materials, we can provide presbyopic patients with a better vision solution that can truly enhance their quality of life.
Dr. Ramsey is in private practice in Charleston, WV. He has been active in the professional and industrial aspects of optometry, with a special interest in ocular allergy.