Cytomegalovirus (CMV) endotheliitis
B. Obtain polymerase chain reaction of aqueous humor for cytomegalovirus (CMV) DNA
The presence of KPs unresponsive to increased topical steroids should raise suspicion of an etiology other than immunologic rejection (choice A), a distinction that may be challenging.1 This patient had coin-shaped aggregates of KP and an elevated IOP in the setting of relative immunosuppression because of topical steroid use. This should raise concern for viral infection, particularly as the incidence of graft rejection after DMEK is low compared with other forms of keratoplasty.2 Although IOP elevation is characteristic of viral endotheliitis,1 the contribution of steroid response cannot be excluded in this patient. Aqueous polymerase chain reaction (PCR) was performed (choice B) and CMV DNA was detected. The lack of vitritis, capsular opacities, corneal stromal infiltrate, and negative donor rim culture results decreased the likelihood of chronic fungal or bacterial graft infection and/or endophthalmitis, making choice C an unnecessarily aggressive option. Empirical treatment with acyclovir would have failed in this case, as it is ineffective against CMV because this virus does not use a viral thymidine kinase3(choice D).