Optometrists are familiar with rose bengal’s clinical value in diagnosing ocular surface disease by staining dead corneal and conjunctival cells. Turns out, it also has a potential role to play in treating infections. The procedure, called rose bengal photodynamic antimicrobial therapy (RB-PDAT), can be considered an appropriate adjunct treatment for severe, progressive infectious keratitis, according to researcher from the University of Miami Miller School of Medicine.

The investigation evaluated 18 patients—seven males and11 females with ages ranging from 17 to 83 years—with active microbiologic infections. Those with a progressive infectious keratitis who did not respond to standard medical therapy underwent RB-PDAT at the Bascom Palmer Eye Institute from January 2016 through March 2018. Of the subjects, 10 had Acanthamoeba, four had Fusarium spp., two had Pseudomonas aeruginosa and one had Curvularia spp. The last patient had no confirmed microbiologic diagnosis.

 The researchers noted a number of conclusions from the study. The most frequent clinical risk factor for keratitis was contact lens wear, present 79% of the time. The average area of epithelial defect prior to the first RB-PDAT treatment was 32mm2±27mm2, and the average stromal depth hyper-reflectivity measured with anterior segment OCT was 269µm±75μm. Patients who underwent RB-PDAT were considered successful cases if they were able to avoid therapeutic keratoplasty. This was achieved in 72% of cases, with an average time to clinical resolution of 46.9±26.4 days.

Naranjo A, Arboleda A, Martinez J, et al. Rose bengal photodynamic antimicrobial therapy (RB-PDAT) for patients with progressive infectious keratitis: A pilot clinical study. Am J Ophthalmol. September 5, 2019. [Epub ahead of print].