Acanthamoeba keratitis treatment outcomes compared for drug delivery by protocol versus physician's individualised...

To compare Acanthamoeba keratitis (AK) outcomes for treatment delivered using a detailed protocol versus physician's individualised treatment.

This double cohort study compared the outcomes of these different delivery methods for PHMB 0.02 % and diamidine 0.1 % dual therapy. The primary outcome was the medical cure rate without surgery within 12 months (MCR_12) and the secondary was visual acuity. Any change of treatment, any surgery, or treatment for >12 months was a failure. Outcomes were both unadjusted and adjusted, using multivariable analysis, for baseline differences affecting outcomes. Patients were from two centres in Milan and London treated at different times; the individualised cohort (1991-2012) and per-protocol cohort (2017-2021).

The individualised cohort included 96 and the per-protocol 47 patients. Both unadjusted and adjusted results were similar. The unadjusted outcomes for both centres combined showed significantly improved outcomes for per-protocol treatment with a 1.59-fold improvement in MCR_12 (95 % CI 1.40-1.80, p < 0.001) and a 2.1-fold increase in visual acuity ≥20/25 (95 % CI 1.34-3.29, p < 0.001). Amongst potential confounding factors examined, neither baseline AK disease stage, treatment centre nor the type of diamidine significantly influenced outcomes.

This study shows significant advantages for the use of protocol delivered versus individualised treatment for AK. The use of evidence-based treatment delivery protocols, like the one used here for AK, might improve outcomes for all causes of microbial keratitis and could offer practitioners and patients the benefit of having an easy-to-follow drug delivery protocol, with known outcomes.