EXTENDED WEAR IN PERSPECTIVE

Background, Convenience and safety are major motivating factors in the choice of a mode of correction for refractive errors. Extended wear o f contact lenses is associated with greater convenience than daily wea r, but questions remain concerning the safety and risks associated wit h this modality. This paper investigates the hurdles that have rendere d extended wear an unfavorable option thus far and seeks to identify s trategies to overcome these obstacles. Method. We review the history o f extended contact lens wear, focusing on soft extended wear for cosme tic use. Results of incidence and relative risk studies for the major complications are scrutinized. The factors that are associated with in creased risk together with mechanisms which have been proposed on base d on scientific research are analyzed to derive strategies for prevent ing adverse reactions in extended wear. Result Infectious keratitis as sociated with extended wear of contact lenses has been identified by t he community as a major issue, although the degree of concern may be d isproportionate. Current perceptions of the relative risk of extended wear versus daily wear in the context of the risk for nonwearers may b e misplaced, and the role of eye closure versus consistency and durati on of wear remains open to debate. In the minds of practitioners and p atients, other adverse reactions may be of greater significance in rej ecting extended wear. Nonetheless, the potential extent of injury from infection demands attention. Studies collectively attest that corneal hypoxia during extended wear is a potential causative mechanism in in fectious keratitis, suggesting that the provision of higher oxygen lev els to the cornea will reduce morbidity rates from this unwanted compl ication, However, the issues of stagnation of the post-lens tear film during eye closure, mechanical properties of the lens, and lens moveme nt remain unresolved and may prove to be contributing factors to adver se responses. Conclusions. Attention to oxygen permeability and mechan ical properties of soft contact lenses should solve the remaining prob lems with extended wear. Materials currently under development promise to meet at least some of the desired properties and may lead to the l ong-awaited advent of safe extended wear.