Contact lens (CL) wearers should take better care of their lens accessories to help prevent contamination, and if they don’t, their storage case can be used to confirm infectious microbial keratitis (MK).

Researchers in Taiwan conducted a prospective case–control study that compared the bioburden of the lens care system in CL wearers between healthy individuals and patients with keratitis. Researchers collected and assessed CL case fluid samples for bioburden assessment with a noninvasive dot hybridization assay (DHA). The test was composed of three universal bacterial probes for detecting all bacteria, genus-specific probes for Pseudomonas and Acinetobacter and one probe for Acanthamoeba. The control consisted of 24 contact lens wearers, while 26 patients had CL-related keratitis. Within the keratitis group, the study classified 12 patients as presumed noninfectious keratitis and 14 patients as confirmed infectious keratitis.

The study found that the storage case bioburden was significantly higher in those with CL-related keratitis than in control subjects. The patients with CL-related keratitis had stronger standardized signals in all three universal bacterial probes. The bioburden was also significantly heavier in those with confirmed infectious keratitis group than in those with presumed noninfectious keratitis.

The researchers note that although the DHA bioburden cannot provide a definite diagnosis, it offers indirect evidence and acts as a risk predictor of CL-related keratitis. They recommend the technique for diagnosing infectious CL-related keratitis in certain cases such as young children, hesitant adults and those with smaller corneal infiltrates, where corneal sampling is inappropriate or inaccessible. The study concludes that periodical screening with the technique could also be useful to promote lens care quality.

Hsiao YT, Fang PC, Chen JL, et al. Molecular bioburden of the lens storage case for contact lens–related keratitis. Cornea. July 23, 2018. [Epub ahead of print].