To investigate whether dry eye disease (DED) is a risk factor for COVID-19.
In this retrospective cohort study, patients who were diagnosed with DED by an ophthalmologist and whose Schirmer test was less than 5mm were identified. Patients who missed follow-up examinations, patients with malignancy, Human Immunodeficiency Virus patients and patients having undergone bone marrow transplantation were excluded. Among the DED patients, patients with positive SARS-CoV-2 PCR tests were identified on October 11, 2020. Subsequently, patients were divided into four age groups (25-49; 50-64; 65-79; and 80+). The COVID-19 prevalence per 100,000 people was determined for each age group, and risk analysis was performed by comparing this with the general population in Turkey.
In total, 10,023 DED patients were identified and included in the study. Among these, the PCR test was positive in 359 patients. The COVID-19 prevalence per 100,000 population in DED patients was calculated as 3581.7, while according to the Ministry of Health data, it was 524.7 in the general Turkish population. The odds ratio of DED patients versus the general population was 6.62 (P<0.001) (7.66 in the 25-49 group; 6.59 in the 50-64 group; 6.23 in the 65-79 group; and 7.24 in the 80+ age group).
The present study showed a high COVID-19 prevalence in DED patients compared to the general population. These findings support the concept that the ocular surface may be a gateway for SARS-CoV-2 and that the tear film is important part of the immune system.

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