Descemet’s stripping automated endothelial keratoplasty (DSAEK) appears to have a higher risk of postoperative fungal infections (predominantly Candida) when compared to penetrating keratoplasty (PK).
Donald T.H. Tan, FRCS, FRCOphth, pointed out that infectious keratitis and endophthalmitis do occur after DSAEK—fungal, bacterial, and viral.
“The higher risk for postop fungal infections seems to relate to donor contamination, lack of anti-fungal prophylaxis in donor storage media, and repeated warming cycles during DSAEK donor tissue processing in eye banks,” said Dr. Tan, Singapore National Eye Centre.
As a result, Dr. Tan said donor rim fungal cultures are recommended for endothelial keratoplasty (EK), and prophylaxis with antifungal therapy is recommended for EK patients with positive donor cultures for fungus.
What the literature says
The first fungal infection occurring after EK was published in 2003,1Dr. Tan said, well before the days of DSAEK.
“Dr. Massimo Busin’s case happened to be a Mycobacterium chelonae interface infection,” Dr. Tan said, that was successfully treated with clarithromycin.
A seminal meta-analysis of endophthalmitis after PK showed that, on average, 14% of donor rims have a positive culture, and of those, 0.2% developed endophthalmitis.2In that analysis, there were 21 concordant cultures, both donor and recipient had the same cultures and the authors specified that there were 10 cases of Candida endophthalmitis.
“In positive donor rim cases in this analysis, after a PK the risk of endophthalmitis is about 1%, and the risk of fungal endophthalmitis is about 3%,” Dr. Tan said.
Since its introduction in 1997, DSAEK has rapidly gain acceptance among corneal surgeons, becoming “the most common form of EK performed today,” Dr. Tan said, but the first published case reports did not appear until 2009 (although the cases occurred in 2007), and both were cases of Candida, with different outcomes.3,4
In the first case, an 80-year-old presented with pseudophakic bullous keratitis that was eventually diagnosed as Candida albicans and the eye required enucleation. In the second case, two cases of donor-host transmission of C. albicans post-DSAEK, and both cases were from the same donor.
“In this case, both eyes were saved,” Dr. Tan said, but that prompted his own case of fungal endophthalmitis from venting incisions.5
“I had to re-open up the previous venting incisions in a repeat DSAEK case,” Dr. Tan said. “They remained open and, therefore, fungal infection through these opened vents occurred.”
In this case, it was Candida parapsilosis and “there are now about 20 reported cases in 15 articles.”
While most of the fungal infections are Candida species, the severity ranges. Risk factors include donor contamination, and a “very important aspect” is interface sequestration, which can hinder the penetration of antifungal treatments.