Contact lens wear is a common predisposing factor in microbial
keratitis and is one of the two preventable risk factors for corneal
infection in a working age population. Our understanding of the prevention and prophylaxis of
contact lens-related corneal
infection is informed by recent epidemiological studies describing the incidence of and risk factors for the disease, the effect of causative organism on disease severity, and an appreciation of individual immune profiles in susceptibility to and severity of the disease. Although contemporary
contact lenses have not reduced the overall incidence of
keratitis, a reduction in morbidity may be achievable through recognition of appropriate risk factors in severe disease, including avoiding delays in presenting for appropriate treatment, and attention to storage case hygiene practise. Severe
keratitis is most commonly associated with an environmental causative organism, and daily disposable
lenses are associated with less severe disease. Pseudomonas aeruginosa remains the commonest cause of
contact lens-related corneal
infection probably because of its unique virulence characteristics and ability to survive in the
contact lens/storage case/ocular environment. In two recent outbreaks of
contact lens-related
infections, there has been a strong association demonstrated with particular
contact lens solutions. Since the recall of these specific
contact lens solutions, the rate of
Acanthamoeba keratitis has remained above the expected baseline, indicating unidentified risk factors that may include environmental exposures. Individual differences in susceptibility to microbial
keratitis may be partly explained by differences in single-nucleotide polymorphisms in certain
cytokine genes, particularly those with a proven protective role in corneal
infection.