Cross-Linking–Assisted Infection Reduction: A Randomized Clinical Trial Evaluating the Effect of Adjuvant Cross-Linking on Outcomes in Fungal Keratitis

Abstract

To determine if there is a benefit to adjuvant corneal crosslinking (CXL) and to compare natamycin versus amphotericin B for filamentous fungal keratitis. Outcome-masked, 2×2 factorial design, randomized controlled clinical trial. Consecutive patients presenting with moderate vision loss from a smear-positive fungal ulcer at Aravind Eye Hospital, Madurai, India. Study eyes were randomized to 1 of 4 treatment combinations using an adaptive randomization protocol. The treatment arms included (1) topical natamycin 5% alone, (2) topical natamycin 5% plus CXL, (3) topical amphotericin B 0.15% alone, and (4) topical amphotericin 0.15% plus CXL. The primary outcome of the trial was microbiological cure at 24 hours on repeat culture. Secondary outcomes included best spectacle-corrected visual acuity (BSCVA) at 3 weeks and 3 months, percentage of study participants with epithelial healing at 3 days, 3 weeks, and 3 months, infiltrate or scar size at 3 weeks and 3 months, 3-day smear and culture, and adverse events. Those randomized to CXL regardless of medication (topical natamycin or amphotericin) had 1.32-fold increased odds of 24-hour culture positivity, although this was not statistically significant (95% confidence interval [CI], 0.57-3.06; P= 0.51). We were also unable to find a difference in 24-hour culture positivity between those randomized to amphotericin and those randomized to natamycin when evaluating as a group regardless of whether or not they received CXL (coefficient 1.10; 95% CI, 0.47-2.54; P= 0.84). The BSCVA was approximately 0.22 logarithm of the minimum angle of resolution (logMAR) (2.2 Snellen lines) worse on average at 3 weeks among those receiving CXL regardless of medication (95% CI,-0.04 to 0.40; P= 0.04) and 0.32 logMAR (3.2 Snellen lines) worse visual acuity at 3 months after controlling for baseline visual acuity (95% CI, 0.03-0.54; P= 0.02). There was no difference in infiltrate or scar size, percentage of epithelialized or adverse events when comparing CXL with no CXL or the 2 topical medications. There appears to be no benefit of adjuvant CXL in the primary treatment of moderate filamentous fungal ulcers, and it may result in decreased visual acuity.