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Hopkins study shows 30-day soft contact lenses pose very small risk of vision loss
December 02, 2005A team of researchers led by the Johns Hopkins Wilmer Eye Institute have determined that the corneal infection rate associated with the use of 30-day -extended-wear contact lenses made from silicone hydrogel is comparable to that previously reported for older lens types worn for fewer consecutive 24-hour periods.
The study, published in the Dec. 1 issue of Ophthalmology, recruited 6,245 patients, 64 percent of them women with an average age of 35, from 131 practices in North America between August 2002 and July 2003. All participants were prescribed and fitted with CIBA Vision NIGHT & DAY® silicone hydrogel soft contact lenses, to be worn for 30 consecutive 24-hour periods. Participants completed a baseline survey to collect information and potential risk factors for infections. At three and 12 months after enrollment, information regarding contact lens wearing schedules, discontinuation of lens wear and the occurrence of red and painful eye infection requiring medical attention was obtained.
Eighty percent of the participants in the study completed 12 months of lens wear and wore their lenses for three or more weeks continuously. The overall annual rate of evident corneal infection was 18 per 10,000. There were two cases of corneal infection with partial loss of vision and an additional eight cases without vision loss. The rate of infection was lower for users wearing the lenses for three or more weeks than for those wearing the contact lenses for less than three-week continuous periods.
"The incidence of vision loss as a result of corneal infections among users of the silicone hydrogel contact lens was low," said Oliver Schein, M.D., M.P.H. lead investigator of the study and the Burton E. Grossman Professor of Ophthalmology at the Johns Hopkins Wilmer Eye Institute. "The overall rate for corneal infection with the wearing schedule of the silicone hydrogel soft contact lenses for up to 30 nights was similar to that reported for conventional (HEMA) extended-wear soft lenses worn for fewer consecutive nights," he added.
Contact lenses are safe, but have some risks not associated with glasses, added Schein. "Daily wear rigid gas-permeable contact lenses appear to have the lowest risk for corneal infection, followed by daily wear soft contact lenses and seven- or 30-day-wear soft contact lenses," said Schein. "Not everyone can wear the lenses successfully for a full 30-nights, but the risk of infection does not appear to increase with greater number of consecutive nights of wear. This is a different pattern than we previously observed with conventional extended-wear soft lenses, where the risk did go up substantially with additional overnight use."
The study also points out that there are many choices for those who do not want to wear spectacles to correct their vision, including hard and soft daily-wear contact lenses, and refractive surgery, such as LASIK (laser-assisted in situ keratomileusis).
"Individuals tend to make choices based on factors such as comfort, convenience, personal preference and safety," notes Schein. "The data are solid that the risks are least with rigid and soft daily-wear contact lenses, more with overnight wear of contact lenses and most with refractive surgery," he adds.
The current study's results should be viewed in light of the first studies to evaluate the original 30-day extended wear lenses, which were approved by the FDA in 1981. Prior to their approval, the original extended wear lenses had been shown in studies to be relatively safe, but as their popularity increased, many cases of corneal ulcers, caused by bacterial infection, resulted in severe vision loss for users.
Studies in the late 1980s showed that the risk of infection was four times greater for the first-generation extended-wear soft contact lenses compared to daily lenses. The risk of infection increased as the duration of consecutive use increased. As a result, the FDA reduced the allowed wearing time for extended-wear contact lenses to just seven consecutive days.
In 2001, the FDA approved CIBA Vision's silicone hydrogel soft contact lenses for continuous wear up to 30 nights. These silicone hydogel lenses allow greater than four times more oxygen through the lenses than did the original extended-wear soft contact lenses and are therefore thought to be offer health benefits for the cornea However, because of the complications seen in the 1980s with the original extended-wear soft contact lenses and therefore the FDA mandated post-market surveillance studies for these new lenses, which the current study satisfies.
Other researchers who participated in the study include James M. Tielsch, Ph.D., professor in the Johns Hopkins Bloomberg School of Public Health; Joanne Katz, Sc.D., professor in the Johns Hopkins Bloomberg School of Public Health; Dennis O'Day, M.D., Eduardo Alfonso, M.D., John McNally, O.D., Robin L. Chalmers, O.D., Joseph Sholvin, O.D., and Mark Bullimore, M.C. Optom., Ph.D.
Johns Hopkins Medical Institutions
"The incidence of vision loss as a result of corneal infections among users of the silicone hydrogel contact lens was low," said Oliver Schein, M.D., M.P.H. lead investigator of the study and the Burton E. Grossman Professor of Ophthalmology at the Johns Hopkins Wilmer Eye Institute. "The overall rate for corneal infection with the wearing schedule of the silicone hydrogel soft contact lenses for up to 30 nights was similar to that reported for conventional (HEMA) extended-wear soft lenses worn for fewer consecutive nights," he added.
Contact lenses are safe, but have some risks not associated with glasses, added Schein. "Daily wear rigid gas-permeable contact lenses appear to have the lowest risk for corneal infection, followed by daily wear soft contact lenses and seven- or 30-day-wear soft contact lenses," said Schein. "Not everyone can wear the lenses successfully for a full 30-nights, but the risk of infection does not appear to increase with greater number of consecutive nights of wear. This is a different pattern than we previously observed with conventional extended-wear soft lenses, where the risk did go up substantially with additional overnight use."
The study also points out that there are many choices for those who do not want to wear spectacles to correct their vision, including hard and soft daily-wear contact lenses, and refractive surgery, such as LASIK (laser-assisted in situ keratomileusis).
"Individuals tend to make choices based on factors such as comfort, convenience, personal preference and safety," notes Schein. "The data are solid that the risks are least with rigid and soft daily-wear contact lenses, more with overnight wear of contact lenses and most with refractive surgery," he adds.
The current study's results should be viewed in light of the first studies to evaluate the original 30-day extended wear lenses, which were approved by the FDA in 1981. Prior to their approval, the original extended wear lenses had been shown in studies to be relatively safe, but as their popularity increased, many cases of corneal ulcers, caused by bacterial infection, resulted in severe vision loss for users.
Studies in the late 1980s showed that the risk of infection was four times greater for the first-generation extended-wear soft contact lenses compared to daily lenses. The risk of infection increased as the duration of consecutive use increased. As a result, the FDA reduced the allowed wearing time for extended-wear contact lenses to just seven consecutive days.
In 2001, the FDA approved CIBA Vision's silicone hydrogel soft contact lenses for continuous wear up to 30 nights. These silicone hydogel lenses allow greater than four times more oxygen through the lenses than did the original extended-wear soft contact lenses and are therefore thought to be offer health benefits for the cornea However, because of the complications seen in the 1980s with the original extended-wear soft contact lenses and therefore the FDA mandated post-market surveillance studies for these new lenses, which the current study satisfies.
Other researchers who participated in the study include James M. Tielsch, Ph.D., professor in the Johns Hopkins Bloomberg School of Public Health; Joanne Katz, Sc.D., professor in the Johns Hopkins Bloomberg School of Public Health; Dennis O'Day, M.D., Eduardo Alfonso, M.D., John McNally, O.D., Robin L. Chalmers, O.D., Joseph Sholvin, O.D., and Mark Bullimore, M.C. Optom., Ph.D.
Johns Hopkins Medical Institutions
Contact Lenses Current Events and Contact Lenses News RSSCataract surgery helps AMD patients; steroid improves DME; online eye health forum
This month's Ophthalmology, the journal of the American Academy of Ophthalmology (Academy) reports on a national study that finds cataract surgery is likely to benefit patients with age-related macular degeneration (AMD) at all stages of the disease, on a clinical trial showing that the steroid triamcinolone may be effective in advanced diabetic macular edema (DME) patients when standard treatment fails, and on the public's use of two Academy-sponsored online eye health forums.
A drug-dispensing contact lens
Taking eye drops multiple times a day can be difficult for patients to do, and because of blinking and tearing, as little as 1 to 7 percent of the dose is actually absorbed by the eye.
Sight for sore eyes
In a world-first breakthrough, University of New South Wales (UNSW) medical researchers have used stem cells cultured on a simple contact lens to restore sight to sufferers of blinding corneal disease.
'Gecko vision': Key to the multifocal contact lens of the future?
Nocturnal geckos are among the very few living creatures able to see colors at night, and scientists' discovery of series of distinct concentric zones may lead to insight into better cameras and contact lenses.
UAB Tear Research Focused on Contact Lens Risks, Benefit
Contact lenses are great for sight, but do they have an impact on general eye health? Researchers at the University of Alabama at Birmingham (UAB) School of Optometry are working to answer that question by analyzing tears.
Violent Video Games Can Improve Vision
Video killed the radio star, the old song goes - but violent video games, a new Tel Aviv University study finds, can also improve the real-world vision of teens who play them.
Eye exercises help patients work out vision problems, UH optometrist says
You've probably been there. In a doctor's office, being advised to do what you dread - exercise. You get that feeling in your gut, acknowledging that, indeed, you should exercise but probably won't. Now imagine that the doctor is your optometrist.
Knobbly kneed ID
Forget LED thumb-pad identification devices, complex retinal laser scanning, or even computerized iris recognition, the way forward for biometric validation is a quick X-ray snapshot of a person's knees, according to a report published in the International Journal of Biometrics.
Strategy Discovered for Fighting Persistent Bacterial Infections
Researchers at National Jewish Health have discovered a promising strategy for destroying the molecular scaffolding that can make Pseudomonas bacterial infections extremely difficult to treat in cystic fibrosis patients, wearers of contact lenses, and burn victims. Jerry Nick, MD, Associate Professor of Medicine at National Jewish Health, and his colleagues report in the April 2009 issue of The Journal of Medical Microbiology that a long string of aspartic acid molecules disrupts the molecular bonds that hold together the structure supporting Pseudomonas biofilms.
Biofilms: Even Stickier Than Suspected
Biofilms are everywhere - in dental plaque and ear canals, on contact lenses and in water pipelines - and the bacteria that make them get more resilient with age, finds a new study in FEMS Microbiology Letters.
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