Clinical Outcomes and In Vitro Growth Inhibition of Severe Fungal Keratitis Treated With Adjunct Rose Bengal Photodynamic Therapy (RB PDT).

PURPOSE: To compare clinical outcomes of fungal keratitis with and without adjuvant Rose Bengal Photodynamic Therapy (RB PDT) and to assess the in vitro antifungal susceptibility of the clinical isolates. METHODS: This retrospective cohort study included 60 patients with culture-proven severe fungal keratitis who were treated at a tertiary referral center between March 2021 and January 2025. Fourteen patients received adjunctive RB PDT for progressive disease despite standard medical therapy, amphotericin B, or voriconazole, whereas 46 patients received standard medical therapy alone. The primary outcome was avoidance of therapeutic penetrating keratoplasty (TPK). The secondary outcomes included time to clinical resolution, recurrence after TPK, and in vitro inhibition of RB PDT. Logistic regression and effect-size analyses were performed. RESULTS: A total of 60 patients (mean age 49.97 ± 15.41 years) were included. TPK was required in 28.6% of RB PDT cases versus 47.8% of the untreated group (odds ratio 0.44, P = 0.235). No recurrence was observed in the RB PDT group compared with 23.8% in the untreated group. Mean time to clinical resolution was shorter in the RB PDT group (43.40 ± 19.27 vs. 70.60 ± 29.24 days; P = 0.017). In the Fusarium subgroup, TPK was required in 14.3% of RB PDT-treated eyes compared with 66.7% of untreated eyes (P = 0.029). The tested isolates demonstrated complete growth inhibition with RB PDT in vitro, including species with variable antifungal susceptibility profiles, except Curvularia spp. CONCLUSIONS: Adjunct RB PDT may reduce the need for surgical intervention and reduce recurrence rates in severe fungal keratitis, particularly in Fusarium infections.