Nov. 9, 2000 -- Even if you're too young for cataracts, you probably know that cataract surgery is one of modern medicine's triumphs. It's evolved from a major procedure, which left patients visually disabled during a long recovery, to a stitchless day surgery, after which visual recovery is virtually immediate. The latest chapter is a "multifocal" lens implant, which corrects both distance and near vision.
Investigators have found that patients who get a multifocal implant have better distance and near vision than those who get conventional monofocal implants, which mainly correct for distance vision, according to a study in the November issue of the journal Ophthalmology. However, the jury may still be out. Multifocals may be more associated with annoying visual disturbances, such as haloes and glare, than are conventional implants.
A cataract is a clouding of the lens, which is used to focus light coming into the eye onto the retina, the light-sensitive layer in the back of the eye. Cataracts are a common product of aging, although they can develop from other causes, such as trauma, inflammation in the eye, diseases such as diabetes, and certain medications. During cataract surgery, the cloudy natural lens is removed, and an implant made of plastic is inserted to take over the job of focusing.
Today, with the conventional implants, a cataract patient often has little if any near vision after surgery. Therefore, reading glasses typically are unavoidable, as they are for most people aged 45 and older. The multifocal lens, which has concentric rings of differing correction strengths, is able to correct for both close-up work and for distance. One multifocal lens implant, ARRAY by Allergan, has been approved by the FDA and was used in this study.
"This was one of several studies consistently demonstrating that patients have a sense of overall well-being and good visual function that exceeds conventional cataract surgery and the monofocal lens," co-author Roger F. Steinert, MD, tells WebMD about the current research. "People often aren't happy with the idea of being dependent on a crutch. They view glasses as a support device. The more they can do without an external crutch, the happier they are." Steinert is an assistant clinical professor of ophthalmology at Harvard Medical School and is in private practice with Ophthalmic Consultants of Boston.
The goal with multifocal implants has been to enable patients to be less dependent on spectacles after surgery. In this study, the investigators followed almost 250 patients, divided almost equally between patients receiving multifocal lenses and conventional lenses. All patients had cataract surgery on both eyes, and they had similar lenses in both eyes. Three months after surgery, patients with multifocals had better average near vision than the group with conventional lenses. The patients' average corrected distance vision was better for the multifocal lenses as well.
Among the patients overall, 32% patients with multifocals and 8% of those with conventional lenses reported that they never wore glasses. On a scale of 0 to 10, with a best possible score of 10, patients with multifocal implants gave their uncorrected vision a score of 8.4, compared to 7.9 for patients with conventional lenses. However, patients with multifocals were more likely to report annoying visual disturbances that can interfere with night driving, such as haloes and glare from headlights.
Experts have diverse opinions on how much an advancement the multifocal implant is. "They're not for everybody. The eye in general can only focus in one plane. When we try to have more than one focus ... there is some loss of contrast," Walter Stark, MD, tells WebMD. "Some patients prefer one focal length [to see for distance] and wear glasses to fine-tune visual acuity, rather than a multifocal lens, which can entail a loss in contrast sensitivity and quality of vision." Stark, who was not involved in the current research, is a professor of ophthalmology and director of cornea and cataract services at the Wilmer Eye Institute of Johns Hopkins University in Baltimore.
"After following patients with multifocals, I have confidence that this is a good lens," William Trattler, MD, tells WebMD. "The one issue is nighttime driving and haloes. Antiglare driving glasses can help minimize this problem." Trattler, who was not involved in the current research, is an instructor in ophthalmology at the University of Miami School of Medicine and an attending surgeon at Miami Baptist Hospital.
Whatever its final role, the multifocal implant is in keeping with other innovations in cataract surgery. Fifty years ago, the researchers who developed lens implants were considered renegades and shunned by their colleagues. Implants are now considered a standard of care for the treatment of cataracts. Future treatment may involve an implant with the elasticity of a youthful lens, so that, as in a young eye, the lens itself can be reshaped by the eye's focusing muscles for near and distance vision, Trattler tells WebMD.
As with any other surgical procedure, cataract patients can help themselves by being informed consumers, Steinert tells WebMD. The type of vision correction that is most appropriate, and therefore the most suitable lens implant, varies among patients, he says.
The study was funded by Allergan Inc., the makers of the ARRAY lens. Study authors Javitt and Steinert have been consultants to Allergan but have no other financial interests in the company or in this product.