Rose Bengal Photodynamic Antimicrobial Therapy (RB-PDAT) for Patients with Progressive Infectious Keratitis: A Pilot Clinical Study

Abstract 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 BSS) to the de-epithelized cornea for 30 minutes followed by irradiation with a 6mW/cm2 custom-made green LED source for 15 minutes (5.4J/cm2). Results The current study included 18 patients (7 males and 11 females) ranging from 17-83 years. 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%) and one 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 ± 27mm2 and average stromal depth hyper-reflectivity measured with anterior segment OCT was 269 ± 75μm. 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-epithelization 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.