Efficacy and Safety of Antifungal Additives in Optisol-GS Corneal Storage Medium

IMPORTANCE Optisol-GS, the most common corneal storage medium in the United States, contains antibacterial but no antifungal supplementation. Most postkeratoplasty endophthalmitis and keratitis cases are now of a fungal origin. OBJECTIVE To assess the efficacy and safety of voriconazole and amphotericin B in reducing Candida species contamination of Optisol-GS under normal storage conditions. DESIGN, SETTING, AND PARTICIPANTS In vitro laboratory study using 15 pairs of research-grade donor corneas and 20-mL vials of Optisol-GS. INTERVENTIONS Twenty vials of Optisol-GS were supplemented with either voriconazole at 1x, 10x, 25x, or 50x minimum inhibitory concentration (MIC) or amphotericin B at 0.25x, 0.5x, 1x, or 10x MIC. Known concentrations of Candida albicans and Candida glabrata were each added to a set of vials. Safety studies were performed by separating 15 pairs of donor corneas into unsupplemented Optisol-GS or Optisol-GS plus an antifungal. MAIN OUTCOMES AND MEASURES Efficacy outcomes were viable fungal colony counts determined from samples taken on days 2, 7, and 14 immediately after removal from refrigeration and after warming to room temperature for 2 hours. Safety outcomes included percentage of intact epithelium and endothelial cell density on days 0, 7, and 14, as well as percentage of nonviable endothelial cells by vital dye staining on day 14. RESULTS Growth of C albicans and C glabrata was observed in all voriconazole-supplemented vials. In contrast, there was no growth of either organism in amphotericin B-supplemented vials, except at 0.25x and 0.5x MIC on day 2, when viable counts of C glabrata were reduced by 99% and 96%, respectively. Compared with paired controls, with the exception of Optisol-GS plus amphotericin B at 10x MIC, donor corneas in supplemented Optisol-GS appeared to have no difference in endothelial cell density reduction, percentage of intact epithelium, or percentage of nonviable endothelial cells. CONCLUSIONS AND RELEVANCE The addition of amphotericin B to Optisol-GS may significantly improve activity against contamination with Candida species, the primary cause of fungal infection after corneal transplantation. This study found significant endothelial toxic effects at the maximal concentration of amphotericin B.