Coronavirus disease 19 (COVID-19) and viral keratouveitis - unraveling the mystery.

To demonstrate viral proteins/inflammatory cytokines in a patient with unilateral keratouveitis. Retrospective case report. A 70-year-old Asian-Indian male presented with acute onset of blurring of vision in the left eye (OS) of 2 days duration. He had was coronavirus disease 2019 (COVID-19)-positive 3 months earlier. He had undergone cataract surgery/retinal laser photocoagulation in both the eyes. The corrected distance visual acuity (CDVA) (Snellen) in the right eye (RE) (OD) and left eye (LE) (OS) was 20/20 and 20/80, respectively. OS showed decreased corneal sensation, Descemet's folds, mild stromal edema, and fine and pigmented keratic precipitates with anterior chamber 1+ flare and 1+ cells. Fundus evaluation showed scattered laser marks in the OD and temporal sectoral laser marks in OS. He was diagnosed with viral keratouveitis in OS. Tear samples were collected on Schirmer's strips and tear wash for mass spectrometry and cytokines, which had 368 and 451 viral proteins in the RE and LE, respectively, using nano liquid chromatography-mass spectrometry, which were more than controls. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and varicella zoster virus proteins were detected. Cytokine analysis using flow cytometer analysis showed higher inflammation in OS as compared to OD. The patient was treated with oral acyclovir and topical steroids and resulted in resolution of his keratouveitis. SARS-CoV-2 proteins were present in the tear sample 3 months after COVID-19. The presence of viral proteins does not indicate causality.