What type of lens is best after cataract surgery – multifocal or monofocal? It depends, study says
Multifocal intraocular lenses improve near vision without compromising distance vision. However, patients with these intraocular lenses may experience reduced contrast sensitivity and they may see haloes around lights. These are the conclusions of a study appearing in the September issue of Ophthalmology, the clinical journal of the American Academy of Ophthalmology, the Eye M.D. Association.
Monofocal lenses are the current standard of treatment, but usually require spectacles for near vision. The choice between the two types of lenses depends on patients motivation to be free of glasses and contact lenses and on their having realistic expectations about the outcomes and compromises involved.
In this systematic literature review and meta-analysis of eight randomized controlled trials, the researchers examined a number of different outcomes: distance and near visual acuity, both unaided and corrected; spectacle independence; depth of field; contrast sensitivity; glare; subjective assessment of quality of life or visual function; and surgical complications.
Though there was significant variability in outcomes among the trials, in general it was found that distance acuity was similar in multifocal and monofocal intraocular lenses, and that unaided near vision tended to improve with the multifocal lens. Independence from spectacles was found in 26 percent to 47 percent of patients with multifocal lenses, but only in 1 percent to 11 percent of those with monofocal lenses. In addition, multifocal lenses increased depth of field. However, the multifocal lens also reduced contrast sensitivity and resulted in the subjective experience of seeing haloes around lights.
"This study is a very realistic interpretation of the multifocal versus monofocal tradeoff," said Academy spokesperson Samuel Masket, MD, clinical professor of ophthalmology at the Jules Stein Eye Institute, UCLA School of Medicine. "The key to choosing multifocal lenses is strong motivation on the part of the patient to be free of glasses and contact lenses. The patient must consciously accept a reduction in the quality of vision in order to have just under a 50-50 chance of being spectacle free."
Dr. Masket said because of the information and advertising about refractive surgery outcomes, many patients have high expectations. "They often anticipate that lens replacement surgery is equivalent to refractive surgery. In fact, as the study indicates, current multifocal lenses may or may not match those expectations. He added that truly accommodating intraocular lenses, which move back and forth inside the lens capsule so the eye can focus both near and far, are currently under development and will probably replace the existing types of lenses in four to six years.
The American Academy of Ophthalmology is the worlds largest association of eye physicians and surgeons – Eye M.D.s – with more than 27,000 members worldwide. For more information about eye health care, visit the Academys partner Web site, the Medem Network at www.medem.com/eyemd. To find an Eye M.D. in your area, visit the Academys Web site at www.aao.org.
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