prescribing for presbyopia
the Time for Monovision Over?
BY CRAIG W. NORMAN, FCLSA
For quite some time I've been contemplating exactly what place monovision has in presbyopic contact lens patient management. Our practice, like most, has many monovision wearers, and while we don't necessarily like the idea of not providing patients with maximum vision out of both eyes at all distances, we have learned to live with it when employing monovision. It seems like we don't offer alternatives to monovision wearers if they don't have visual symptoms or complaints, but maybe we should.
So why do we make use of monovision so often? Is it because of a lack of designs? Probably not, as we have a significant number of excellent multifocal and bifocal hydrogel, silicone hydrogel and GP lenses for us to offer to this patient segment. A hybrid lens will also soon be available.
Does ease of fit play a role? Historically that might have been true, but most of the aforementioned designs are relatively simple to fit today.
Is it patient response in that they prefer monocular vision over binocular vision? I doubt it. In fact, Dr. Kathryn Richdale and others from The Ohio State University College of Optometry published a wonderful study in May 2006 called "Comparison of Multifocal and Monovision Soft Contact Lens Corrections in Low-Astigmatic Presbyopic Patients." Richdale et al assessed visual performance and patient satisfaction in a crossover study of 38 presbyopic patients. They randomized the study patients first into either multifocals (Bausch & Lomb SofLens Multi-Focal) or monovision (B&L SofLens 59) for one month. The researchers measured visual performance with high- and low-contrast visual acuity at distance and near as well as near stereoacuity. They measured patient satisfaction using the National Eye Institute Refractive Error Quality of Life Instrument (NEI-RQL) questionnaire and by recording the patients' final lens preference.
Among the many interesting findings in this study:
Patients lost less than one line of vision from the best-spectacle correction with either multifocal or monovision lenses.
The average stereoacuity decreased by 79 seconds of arc with monovision vs. multifocals.
On the NEI-RQL, 76 percent of patients reported that they preferred multifocal contact lenses over monovision.
The authors state that the reason why patients prefer the multifocal contact lens correction to monovision by more than a 3:1 ratio is most likely because the multifocal provided comparable visual acuity without compromising stereoacuity to the same degree as monovision.
Time for a Change
Why do we still use monovision so often? The reasons are multifaceted, but for many it may be nothing more than a habit of taking the path of least resistance and suggesting monovision because it's what we've always done.
Instead, I think we all should consider multifocal and bifocal contact lenses as the first option more often. And when we do, we might be surprised at how positively patients respond. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #134.
Craig Norman is director
of the Contact Lens Section at the South Bend Clinic in South Bend, Indiana. He
is a fellow of the Contact Lens
Society of America and is an advisor to the GP Lens Institute. He is also a consultant to B&L.