Are eyes the windows to COVID-19? Systematic review and meta-analysis

To review and critically appraise the ocular manifestation and the presence of SARS-CoV-2 through PCR positivity from ocular samples in COVID-19-related patients. Moreover, to evaluate the time and severity association of ocular manifestation to systemic disease of COVID-19.

A systematic literature search from PubMed, ScienceDirect and Google Scholar databases was performed using standardised Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. Selected keywords were related to COVID-19, ocular manifestation and PCR testing of SARS-CoV-2. Studies were assessed for their validity, and the data were extracted by two independent reviewers. Observational, case series and case report studies were included if they met the selection criteria. Meta-analysis was performed to estimate the pooled prevalence of ocular manifestations and PCR positivity from tears.

Thirty-one articles were qualitatively reviewed, and 14 studies were included in the meta-analysis. The pooled prevalence of ocular manifestation among COVID-19-related patients was 0.05 (95% CI 0.02% to 0.08). The overall PCR from tears samples positivity rate from COVID-19-related patients presenting with ocular manifestation was 0.38 (95% CI 0.14% to 0.65). Ocular manifestation could precede systemic manifestation in about 0.28 (95% CI 0.05% to 0.58) of COVID-19-related patients with ocular manifestations. Besides, ocular manifestation was not associated with a severe form of COVID-19.

Although the overall number of ocular manifestation and SARS-CoV-2 PCR positivity rate from ocular samples was very low, around a quarter of COVID-19-related patients with ocular manifestation presented their ocular manifestation earlier than the systemic manifestation regardless of the severity. Interestingly, SARS-CoV-2 PCR was positive from one-third of ocular samples, which could potentially be the source of infection to the respiratory tract and the environment, although the infectivity is yet to be determined.