We read with great interest the article “Immune Ring Formation Associated with Cytomegalovirus Endotheliitis,” by Chee and associates. In their series of 72 cases of cytomegalovirus (CMV) infection, they found corneal immune rings (IR) in 3 CMV endotheliitis cases. Although the IR often is related to herpes simplex stromal keratitis, they suggested that their cases with IR were caused by the CMV infection. Their diagnosis was based on DNA of CMV detected in the aqueous by real-time polymerase chain reaction, not on the direct histopathologic evidence of CMV particles or antigen in the corneal tissue. CMV was detected in aqueous only; however, one can not rule out the possibility that the ring was caused by herpes simplex virus (HSV). In 2 of our corneal endotheliitis cases, DNA of both HSV and CMV were detected in the same eye, which suggested that HSV and CMV can coexist in corneal endotheliitis cases. Although their 3 cases with IR improved after the valganciclovir treatment, because valganciclovir also has an effect on HSV, the possibility of HSV infection still can not be ruled out. Because HSV particles and antigen were detected in the IR of herpes simplex stromal keratitis, the results reported by Chee and associates will be more convincing after they have direct histopathologic evidence from their cases to prove the their assumption.