Combining corneal cross-linking (CXL) with topical anti-fungal drugs didn’t improve outcomes for recalcitrant deep stromal fungal keratitis in this randomized, controlled trial. Instead, it increased the chance of perforation.
Even though this was a small study, the findings are important because those who received CXL did worse than those who continued with anti-fungal therapy alone. In fact, visual acuity also tended to be worse in CXL-treated eyes, although this difference was not statistically significant. Nevertheless, the authors say it’s possible CXL could be beneficial for less advanced fungal keratitis.
Investigators randomized 13 patients who failed to respond to 2 weeks of topical treatment to receive adjuvant CXL (Dresden protocol) or to continue on topical treatment alone. At 6 weeks, 5 of 6 eyes in the CXL group experienced treatment failure compared to 3 of 7 eyes treated with topical therapy.
It’s unclear why CXL was ineffective in this study, but the authors say it’s possible that CXL’s efficacy depends on the organism, severity of the ulcer (e.g., infiltrate depth, infiltrate diameter, stromal thinning, limbal involvement), host response or other poorly understood factors.
Overall, more studies are needed to delineate the role of CXL in treating infectious keratitis, including which types of patients (based on organism, clinical presentation and timing) would benefit from CXL and which CXL protocols should be used.