Contact Lenses and Microbial Keratitis

Microbial keratitis, an infection of the cornea, is the most serious complication of contact lens wear. It is uncommon, but it can cause corneal scarring and permanent loss of vision. Bacteria, particularly Pseudomonas aeruginosa, cause most cases, while fungi and the free living amoeba Acanthamoeba are less common but harder to treat.

Epidemiological studies have consistently identified overnight or extended wear as the strongest risk factor, and exposure of lenses and cases to tap water, swimming in lenses, poor case hygiene, and use beyond the intended replacement period are also associated with higher risk. Acanthamoeba keratitis is strongly linked to water exposure and can cause severe pain and a prolonged course. Typical symptoms of keratitis include pain, redness, light sensitivity, discharge, and blurred vision.

Diagnosis involves slit lamp examination and often corneal scrapings for culture, and treatment uses intensive antimicrobial eye drops. Decorative lenses obtained without fitting by an eye care professional have been associated with serious infections..