Oliver D. Schein, M.D., whose landmark 1989 study cast doubt upon the safety of extended contact lens wear, is probably the last person youd expect a contact lens manufacturer to want studying its lenses.
Guess again. Earlier this week, CIBA Vision announced a research agreement with Johns Hopkins University to conduct a post-market study of Focus Night & Day. CIBA Vision agreed to conduct a post-market study when the FDA approved the lens in October 2001 for up to 30 nights of continuous wear.
Dr. Schein was a principal investigator in the 1989 study, published in the New England Journal of Medicine. That study found a much higher incidence of ulcerative keratitis with extended wear vs. daily wear20.9 cases vs. 4.1 cases per 10,000prompting contact lens manufacturers to voluntarily reduce allowable wearing times from 30 to seven days.1
The new study will track 5,000 patients in the United States wearing Night & Day for a year. Dr. Schein and a team from the Johns Hopkins Wilmer Eye Institute and Bloomberg School of Public Health worked with CIBA Vision to design the study. Dr. Schein also has chosen an independent committee of ophthalmologists, optometrists and epidemiologists, who will review the studys progress and analyze adverse events.
Two study features were most important to us, says John McNally, O.D., head of continuous wear contact lens research at CIBA Vision. We wanted a real world setting where we could monitor the product in the way it is actually used, and we wanted to select an independent board of expert reviewers to assess the performance.
Focus Night & Day and Bausch & Lombs PureVision, which is also approved for up to 30 days of wear, are silicone hydrogel lenses designed to avoid hypoxia, a major problem with earlier-generation extended wear materials. Focus Night & Day (lotrafilcon A) and PureVision (balafilcon A) have oxygen transmissibility (Dk/t) of 175 and 110, respectively.
The lenses are also designed to provide adequate movement on the eye to prevent debris buildup under the lens, and improved deposit resistance to lower the risk of Pseudomonas aeruginosa. A recent study by Dwight Cavanaugh, M.D., Ph.D., and his colleagues at the University of Texas Southwestern Medical Center found significantly less Pseudomonas binding to epithelial cells in the eyes of those who wore silicone hydrogel lenses vs. conventional soft lenses.2
1. Poggio EC, Glynn RJ, Schein OD, et al. the incidence of ulcerative keratitis among users of daily-wear and extended-wear soft contact lenses. N Engl J Med 1989 Sep 21;321(12):779-83.
2. Ren D, Yamamoto K, Ladage P, et al. Adaptive effects of 30-night lens wear of hyper-O(2) transmissible contact lenses on bacterial binding and corneal epithelium: a one-year clinical trial. Ophthalmology 2002 Jan 190:27-40.
