Retinal findings on OCT in a convalescent COVID-19 Patient Cohort

Purpose : Possible retinal involvement by COVID-19 has been a topic of recent debate. We performed a prospective study to determine whether retinal abnormalities can be identified on OCT in convalescent fully recovered patients following COVID-19 infection. Methods : This is a prospective, case-controlled study that recruited COVID19 patients who were admitted to the United Christian Hospital Hong Kong, China. At 2 months postrecovery, patients' visual acuity, refraction were measured. Spectral-domain OCT of the macula and retinal nerve fiber layer and enhanced depth imaging were performed. Agematched and refraction-matched healthy individuals that were not infected with COVID-19 were enrolled as controls. Qualitative and quantitative assessment of retinal abnormalities on structural OCT and retinal and choroidal layer thickness are the main outcomes. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and volcano plot were applied to data analysis. Results : 20 subjects (40 eyes) with COVID-19 and 25 (50 eyes) age-matched asymptomatic healthy controls were enrolled. Structural OCT abnormalities could be observed in 24% of control eyes and in 25% of COVID-19 subjects. No differences were observed between the post-COVID-19 cohort and the healthy controls for any qualitative retinal abnormalities. PCA and the PLS-DA demonstrated a substantial overlap in the 95% confidence region between the two groups. Further analysis showed there are no significant differences in any quantitative feature including retinal volume, choroidal thickness, retinal layer thicknesses in various macular regions, and peripapillary nerve fiber layer thickness with the exception of the retinal outer temporal quadrant region. However, the impact this quantitative feature has on the dataset is miniscule given that its fold change impact was below 1.0. Conclusions : Following full recovery from symptomatic COVID 19 infection no significant abnormalities were evident on structural OCT. Although long-term damage to the retina appears to be uncommon after COVID-19 infection, this study provides valuable insight into the recovery process after COVID-19 and provides potential retinal features that should be considered in the larger population to separate between these groups.