The clinical use of contact lenses and collagen shields.

Contact lens wear before and after photorefractive or phototherapeutic keratectomy with excimer lasers has become an increasingly interesting subject. No negative side effects of contact lens wear prior to photorefractive keratectomy have yet been shown and refractive errors postoperatively do not seem to constitute a major practical problem. Normal side effects include the risk of bacterial infection and keratitis. The major pathogen in this context is still Pseudomonas aeruginosa, although increased insight into the mechanisms of bacterial adhesion and improvements in cleaning procedures now allow more effective preventive care of contact lenses themselves and of contact lens cases. Tear fluid research using leucotriene C4 as a possible indicator for subclinical inflammation has led to interesting results, and the importance of the arachidonic pathway and its metabolites has become more evident. These advances contribute considerably to the safe use of contact lenses in clinical ophthalmology, although major innovations such as the multifocal contact lenses have not reached the stage of perfection.