By Clark L. Springs, MD
This prospective study found that the addition of amphotericin B to Optisol-GS leads to a significant reduction in Candida species, the most common cause of post-corneal transplant fungal infection. At the highest concentration (10x MIC), there was significant corneal endothelial toxicity.
Optisol-GS, the most common corneal storage medium in the United States, contains antibacterial but not antifungal supplementation. However, most post-keratoplasty endophthalmitis and keratitis cases are now of a fungal origin.
In this study, the authors assessed the efficacy and safety of voriconazole and amphotericin B in reducing Candida species contamination of Optisol-GS under normal storage conditions.
They supplemented 20 vials of Optisol-GS with either voriconazole at 1×, 10×, 25×, or 50× MIC or amphotericin B at 0.25×, 0.5×, 1×, or 10× MIC, and added known concentrations of Candida albicans and Candida glabrata to the vials. Safety studies were performed by separating 15 pairs of donor corneas into unsupplemented Optisol-GS or Optisol-GS plus an antifungal.
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 0.25× and 0.5× MIC on day two, 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 10× 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.
They note that a recent statement by the Eye Bank Association of America Medical Advisory Board did not recommend antifungal supplementation of corneal storage media, partly because of insufficient evidence regarding efficacy and safety. The authors write that they hope this study helps to provide such evidence.
They conclude that although this study suggests that a low concentration of amphotericin B might be a safe and efficacious addition to storage media, a larger study is warranted to confirm these findings.