LAUSR

PURPOSE To study the efficacy and safety profile of topical absolute ethanol in the treatment of Pythium insidiosum keratitis. METHOD Microbiological, clinical, and histopathological assessments were performed to study the effects of absolute ethanol on P. insidiosum keratitis. In addition, infrared spectroscopy was performed to assess the corneal penetration of ethanol. RESULTS Microbiological tests revealed that ethanol inhibited the growth of P. insidiosum at concentrations even as low as 20% as compared to Candida albicans and Aspergillus flavus, where minimal growth was noted. However, at 40%, 60%, 80%, and 99.9% of ethanol, complete inhibition of growth was noted for all organisms. Histopathology of the absolute ethanol-treated cadaveric cornea showed the compaction of collagen and no stromal necrosis. Infrared spectroscopy revealed secondary structural changes in collagen in the ethanol-treated cadaveric corneas as compared to controls. Clinically, 1 case with a recurrence of P. insidiosum after therapeutic penetrating keratoplasty resolved with the topical application of absolute ethanol, and the other case, where corneal scraping had grown Pythium within 24 hours, failed to grow the organism from the corneal button which was treated with absolute alcohol preoperatively. After therapeutic penetrating keratoplasty, there was no recurrence, and the graft epithelized well. CONCLUSIONS Ethanol can be considered an option for treating P. insidiosum keratitis; however, the exact dose and strength of ethanol which will be most effective needs further work.