Bacterial, fungal infections
Over a five-year period, 14 cases of bacterial infections during EK surgeries were reported in nine articles, with causes linked to Pseudomonas, Staphylococcus aureus, microbacterial, and Streptococcus endocardium, with the majority being Pseudomonas and S. aureus.
“Other than the risk factors for fungi, some also have suggested contact lens wear combined with steroid use, which kind of makes sense,” Dr. Tan added.
The Eye Bank Association of America (EBAA) reported in 20136that from 2007 to 2010, “there were 31 cases of fungal infections, both keratitis and endophthalmitis, and that made it 1.4 cases for 10,000 transplants,” Dr. Tan said.
Fungal infections were “commonly reported after EK. It was 0.022% versus 0.012%, but the difference failed to reach statistical significance,” he pointed out.
In 2015, the EBAA found that in 2013, there were 26 cases of fungal infections, making the infection rate of 0.039%, which was statistically significantly higher (p < 0.01). The majority of these were endophthalmitis and mostly Candida, (16 cases, 62%).
Additionally, over half of the EK cases were from precut tissue performed in the eye bank. “With eye bank preparation, the risk was 0.11% compared to surgeon preparation in the OR, which was 0.01%, and again this reached statistical significance,” Dr. Tan explained.
Warming tissue, other causes
Dr. Tan said the increasing incidence of postoperative fungal infection following DSAEK and the high incidence with eye bank preparation should be confirmed, the causes identified, and the issues addressed.
The effect of warming donor corneas to room temperature (which occurs frequently in EK due to the need for image assessment of the endothelium as well as pre-cutting of tissue) may play a role.
Fungal growth is static during refrigeration, “but during the warming period, Candida started to grow, all three Candida subspecies, and then the tissue is stored at room temperature,” Dr. Tan said. Tu, et al further showed the number of warming cycles is equally important; with each one-hour warming cycle, a marked increase in Candida occurs.7
“There is a significant need for antifungal supplementation,” Dr. Tan said.
Over the past few years, there has been a reported increase in post-DSAEK cytomegalovirus (CMV) endotheliitis, mostly in Asian countries, but “several cases” have been reported in the United States.
“The diagnostic dilemma is that it looks very similar to an allograft rejection episode,” Dr. Tan said, and diagnosis requires identification of CMV antigen by an AC tap; the treatment is to stop or reduce topical steroids, and to start topical ganciclovir and oral valganciclovir with “a high index of suspicion warranted for these cases.”
Vigilance about potential infections in the EK setting will help mitigate the potential devastating effects, and hopefully lower the incidence even further.