Clinical Outcomes And In Vitro Susceptibility Analysis Of Severe Fungal Keratitis Treated With Adjunct Rose Bengal Photodynamic Antimicrobial Therapy (Rb-Pdat)

To compare clinical outcomes of fungal keratitis with and without treatment of adjunct Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) and to assess in vitro antifungal susceptibility of the clinical isolates.

Department of Ophthalmology and Visual Science, External Diseases and Cornea Service, Federal University of São Paulo, São Paulo, Brazil

This retrospective cohort study included 60 patients with culture-proven severe fungal keratitis treated at a tertiary referral center between March 2021 and November 2024. Fourteen patients received adjunct RB-PDAT for progressive disease despite standard medical therapy (SMT), while 46 patients received SMT alone. The primary outcome was avoidance of therapeutic penetrating keratoplasty (TPK). Secondary outcomes included time to clinical resolution, recurrence after keratoplasty, and in vitro RB-PDAT susceptibility. 

A total of 60 patients (mean age 49.97 ± 15.41 years) were included. Therapeutic keratoplasty was required in 28.6% of RB-PDAT cases versus 47,8% of controls (OR 0.44, p=0.235). No recurrences were observed in the RB-PDAT group compared to 23,8% in controls. Mean time to clinical resolution was shorter in the RB-PDAT 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-PDAT-treated eyes compared with 66,7% of controls (p=0,029%). Tested isolates demonstrated complete growth inhibition with RB-PDAT in vitro, including species with variable antifungal susceptibility profiles, except for Curvularia spp.

Adjunct RB-PDAT may reduce surgical intervention and recurrence rates in severe fungal keratitis, particularly in Fusarium infections.