Microbial contamination of donor corneas and post-keratoplasty endophthalmitis: a comparison between Japanese and U.S. eye banks using cold storage

This study evaluated the prevalence and microbial spectrum of positive corneoscleral donor rim cultures and the associated risk factors for post-keratoplasty infection in Japan. We retrospectively included consecutive corneal transplantations performed by a single surgeon between April 2015 and September 2021. Donor corneas were obtained from eye banks in Japan ( n = 134) or the United States ( n = 365) and preserved using cold storage. Donor corneoscleral rim cultures were obtained during surgery. Culture positivity and microbial profiles were analyzed. Risk factors for contamination were evaluated using logistic regression. Overall, 78 (15.6%) were culture-positive. Domestic grafts had significantly higher microbial contamination rates than overseas grafts (30.6% vs. 10.1%, P < 0.001), whereas fungal contamination rates did not differ between groups (1.5% vs. 1.9%, P = 1.000). In the multivariate analysis, overseas eye bank origin was independently associated with a lower risk of microbial contamination (OR 0.259, 95% CI, 0.139–0.486; P < 0.001). Post-keratoplasty endophthalmitis occurred in three cases (0.6%), all of which were associated with positive fungal cultures. Therefore, fungal pathogens may play a key role in increasing clinically significant postoperative endophthalmitis risk after keratoplasty, highlighting the importance of targeted donor tissue screening and postoperative management.