Prevalence and features of keratitis with quantitative polymerase chain reaction positive for cytomegalovirus

To assess corneal scrapings and aqueous humor samples analyzed by polymerase chain reaction (PCR) that were positive for cytomegalovirus (CMV) in patients with keratitis of unknown origin and to investigate their clinical manifestations.

Retrospective, interventional case series.

Seventy-eight patients with epithelial (n=37), stromal (n=12), or endothelial keratitis (n=29) of unknown origin examined at the Osaka University Medical Hospital.

Clinical examination and tears, corneal scrapings, and aqueous humor specimens were evaluated by real-time PCR for CMV.

Quantification of CMV DNA at the diagnosis of each type of keratitis with unknown origin and monitoring during the therapeutic course for CMV-positive cases.

No cases of epithelial or stromal keratitis had CMV DNA. Seven of 29 corneal endotheliitis cases (24.1%) were positive for CMV. Cytomegalovirus-positive cases of corneal endotheliitis characterized by localized corneal edema and keratic precipitates included 4 patients who had undergone penetrating keratoplasty and were refractory to the treatment for graft rejection and 3 patients with idiopathic endotheliitis. Cytomegalovirus DNA copy numbers were estimated and ranged from 6.3x10(4) to 3.6x10(6)/ml. In all positive cases, the numbers of CMV DNA copies decreased within weeks during treatment with systemic and topical ganciclovir (GCV) combined with a topical steroid. Five eyes (62.5%) had clinical improvement. In cases of endothelial keratitis, diabetes mellitus was significantly higher in patients positive for CMV (71.4%) than in patients negative for CMV (18.2%, P=0.016, chi-square test).

A total of 24.1% of cases with corneal edema of unknown origin were CMV positive and should be included in the differential diagnosis of idiopathic corneal endotheliitis or graft edema after penetrating keratoplasty, especially for bullous keratopathy. Real-time PCR for CMV, based on the diagnosis and monitoring of the clinical course, may be useful. Cytomegalovirus corneal endotheliitis requires early appropriate treatment using GCV. Because clinical remission after GCV may depend on the area of normal endothelium, early diagnosis and therapy are important for CMV corneal endotheliitis.