Contact lens-associated microbial keratitis.

During a 14-year period, 42 cases of microbial keratitis were associated with contact lens (CL) wear. Pseudomonas aeruginosa was isolated in 40% of the cases and Staphylococcus in 31%; Streptococcus pneumoniae, alpha-hemolytic Streptococcus, and Serratia marcescens were the next most commonly isolated pathogens. There was a single fungal corneal ulcer. Bandage CL use was associated with a high prevalence of infection with quasi-commensal organisms and with polymicrobial keratitis, a pattern of disease quite distinct from that induced by other types of CLs. Marked visual loss frequently occurred. There was a disturbing increase in the number of infections associated with extended-wear CLs (worn for either aphakia or myopia) over the last 18 months of the study.