Assessing the risks of extended wear.

Risks associated with contact lens wear vary in the literature with respect to identity and severity. To more adequately portray these risks, a meta-analysis of complications was performed, using (1) contact lens package inserts; (2) reports of complications in nonreferral populations of extended-wear patients; (3) reports of complications for contact lens wearers seen in emergency rooms; (4) reports of corneal ulceration in referral populations of contact lens wearers; and (5) studies comparing daily- and extended-wear patients in terms of ulcerative keratitis. Total complication rates for extended wear of rigid and hydrogel lenses ranged from 7% to 31% of eyes over corresponding mean wearing durations of 12 to 22 months. Mean corneal ulceration rates were 0.44% and 0.21% per eye per year for the extended wear of hydrogel and rigid contact lenses, respectively. The risk of ulcerative keratitis among hydrogel extended-wear patients was 4.2 times that of hydrogel daily-wear patients, and rigid lens extended wear entailed roughly half of the risk of ulcerative keratitis of hydrogel extended wear. When applied to contact lens wearers in the United States, these risks indicate an estimated incidence of ulcerative keratitis greater than 71,000 cases per year, averaging approximately 1.7 ulcerations annually for each eye care practitioner in the United States.