Rose Bengal-mediated PDT appears effective in fungal keratitis

This prospective study found that rose bengal–mediated photodynamic therapy (PDT) successfully inhibited the growth of three different fungal isolates.

The authors compared the in vitro effect of rose bengal and riboflavin as photosensitizing agents for PDT on three fungal isolates (Fusarium solani, Aspergillus fumigatus, Candida albicans) recovered from patients with fungal keratitis. Treatment groups included: no treatment; 0.1% rose bengal alone; 518 nm irradiation alone; riboflavin PDT (375 nm irradiation); and rose bengal PDT (518 nm irradiation). Plates were then placed in a 30 C incubator and observed for growth.

Rose bengal–mediated PDT successfully inhibited growth of all three types of fungi. No other experimental groups, including riboflavin-mediated PDT, had any inhibitory effect on the isolates.

This study is important as the incidence of fungal keratitis is on the rise both in the United States and worldwide. With natamycin being the only commercially available agent to treat the disease, new therapies are needed to combat this visually threatening condition.

Riboflavin PDT has been used as an off-label treatment in severe bacterial keratitis but its efficacy in fungal keratitis is not known. This study suggests that riboflavin PDT may not be an appropriate therapy in this condition. Further studies using in-vivo models will need to confirm these findings.