People who recovered from COVID displayed alterations in their retinal microvasculature, including a significantly lower vessel density in the superficial and deep retinal capillary plexus, researchers recently reported.

This comparative, cross-sectional, observational study included 31 recovered COVID-19 patients and 23 healthy controls who underwent OCT angiography.

The team observed significantly lower mean superficial (44.98 vs. 48.36) and deep (49.74 vs. 53.03)vessel densities of the foveal and parafoveal regions in the study cohort compared with controls. Within the study cohort, mean vessel densities and foveal avascular zone (FAZ) area were lower in patients with a history of COVID-19 hospitalization but did not reach statistical significance. While the FAZ area was greater in the study cohort, this difference was not statistically significant (0.27 vs. 0.24).

The researchers noted that the cause of retinal capillary alterations in subjects was unclear but speculated that secondary effects of inflammation may have played a role.

They were also cautious about drawing broad conclusions about COVID patients as a whole. “Although our cohort of 31 cases with inactive disease may not be representative of the much larger population of infected COVID patients worldwide,” the authors wrote, “it is interesting to note that retinal capillary alterations were detected in our study even though the affected cohort was young without pre-existing systemic illness, indicating that potentially more serious retinal complications may develop in higher-risk COVID subjects.”

Nevertheless, they suggest that the findings argue in favor of larger-scale studies to continue to document the potential involvement of the retina by COVID-19.

Abrishami M, Emamverdian Z, Shoeibi N, et al. Optical coherence tomography angiography analysis of the retina in patients recovered from COVID-19: a case-control study. Can J Ophthalmol. November 14, 2020. [Epub ahead of print].