OCT 24, 2008
Comprehensive Ophthalmology, Cornea/External Disease
This two-year, prospective, case-control study included 367 contact lens wearers with presumed microbial keratitis (MK) seen at a Moorfields, and a large control group of CL wearers. While the relative risk of MK was significantly increased with daily disposable (DD) contact lenses, vision loss is less likely to occur in DD than in reusable soft CL users.
Researchers suggest that different brands of CL may be associated with significantly different risks of keratitis, and conclude that lens/ocular surface interactions maybe more important in the development of corneal infection than oxygen levels and CL case contamination.
They write:
"The disappointing finding that silicone hydrogel CL use has no major effect on MK suggests that other, possibly less easily modifiable factors, such as tear film stagnation, ocular surface compartmentalization behind the lens, and reduced corneal epithelial cell turnover with soft lens wear may play a more significant role in the development of corneal infection than corneal hypoxia. These factors may also be more critical than the effect of exposure to a contaminated CL case, as shown by the finding that no brand of DD CL has had the expected effect of reducing the risk of MK. On the other hand, the finding that the introduction of the DD CL has had a brand-dependent effect on the risk of MK suggests that a difference in soft CL design and/or polymer, rather than its method of use, can modify susceptibility to MK. This has further implications, both for our understanding of the pathogenesis of MK in CL users and/or future lens design."