Infectious keratitis is a major sight-threatening complication of contact lens (CL) wear and its incidence has remained stable for the last decades, in spite of the improvements in CL materials and care systems.
1 Given that the CL storage case is the main source of contamination in lens care equipment,
Kuo et al.
2 used a DNA dot hybridization assay to identify bacterial presence in orthokeratology CL cases from normal wearers. They demonstrated significant correlation between bacterial colony-forming units found in culture and hybridization signal intensities in 2 of 3 universal bacteria probes. Further, they used specific probes for
Pseudomonas,
Acinetobacter, and
Klebsiella, and successfully traced these bacteria in all cases that had positive culture and also in some other cases in which the same bacteria did not grow in culture.
Molecular methods have emerged as accurate alternatives for microbial identification, but it is necessary to formally and continually compare these newer methods with traditional culture technique.
3 Molecular testing is able to detect bacteria in very low density and regardless of their viability status. In a clinical context, this extremely high sensitivity may be undesired because nonviable bacteria do not cause infectious keratitis. However, this feature is especially interesting when evaluating a CL care system, since nonviable microorganisms indicate the eradicating efficacy of a disinfection system. A previous study showed that infrequent storage case replacement, poor storage case hygiene, and solution type are independent risk factors for moderate to severe microbial keratitis.
1 Therefore, lens care quality is among our main concerns to prevent ocular infection and vision loss in CL wearers.