Rose Bengal Photodynamic Antimicrobial Therapy for Patients With Progressive Infectious Keratitis: A Pilot Clinical Study.

Purpose: To report clinical outcomes of rose bengal photodynamic antimicrobial therapy (RB-PDAT) as an adjunct treatment for severe, progressive infectious keratitis.

Design: Consecutive interventional case series.

Methods: Patients with progressive infectious keratitis unresponsive to standard medical therapy underwent RB-PDAT at the Bascom Palmer Eye Institute from January 2016 through March 2018. RB-PDAT was performed by applying a solution of rose bengal (0.1% or 0.2% RB in balanced salt solution) to the de-epithelialized cornea for 30 minutes, followed by irradiation with a 6 mW/cm custom-made green LED source for 15 minutes (5.4 J/cm).

Results: The current study included 18 patients (7 male and 11 female) ranging from 17 to 83 years old. Acanthamoeba was the most frequent microbe (10/17; 59%), followed by Fusarium spp. (4/17; 24%), Pseudomonas aeruginosa (2/17; 12%), and Curvularia spp. (1/17; 6%); 1 patient had no confirmed microbiologic diagnosis. Main clinical risk factor for keratitis included contact lens wear (79%). The average area of epithelial defect prior to first RB-PDAT was 32 ± 27 mm and average stromal depth hyperreflectivity measured with anterior segment optical coherence tomography was 269 ± 75 μm. Successful RB-PDAT (avoidance of therapeutic keratoplasty) was achieved in 72% of the cases, with an average time to clinical resolution (decreased pain and inflammation with re-epithelialization and infiltrate resolution) of 46.9 ± 26.4 days after RB-PDAT. Time of follow-up after RB-PDAT was 13.3 ± 5.7 months.

Conclusion: RB-PDAT can be considered as an adjunct therapy for cases of severe, progressive infectious keratitis before performing a therapeutic keratoplasty.