Effects of Covid-19 Disease on Retinal and Choroidal Thickness by Optical Coherence Tomography.

PURPOSE: The aim of our study was to evaluate the subclinical changes in the macula, retinal nerve fiber layer (RNFL) and choroidal thickness after COVID-19 infection using spectral domain optical coherence tomography (OCT).

METHODS: Our study was prospectively designed and involved 170 eyes of 85 patients. Patients with PCR positive COVID-19 infection were examined in the ophthalmology clinic before and after infection were included. All included patients had mild COVID-19 with no hospitalization and no need for intubation. Control ophthalmic examination was repeated at least six months after PCR positivity. Macular and choroidal thickness and RNFL parameters were compared before and at least 6 months after PCR positive COVID-19 infection using OCT.

RESULTS: When the mean macular thickness data were evaluated, a significant decrease was detected in the inner (mean difference -3.37 µm; CI95% -6.09 to -0.65, P=0.021) and outer (mean difference -6.56 µm; CI95% -9.26 to -3.86, P<0.001) temporal segments and the inner (mean difference -3.39 µm; CI95% -5.46 to -1.32, P=0.002) and outer (mean difference -2.01 µm; CI95% -3.70 to -0.31, P=0.018) superior segments in the post-COVID-19 measurements compared to pre-COVID-19 measurements. Similarly, on RNFL evaluation, some thinning was evident in the temporal superior (mean=1.14 µm, P=0.004) and temporal inferior (mean=1.30 µm, P=0.032) regions. All choroidal regions, including central, nasal 500 µm and 1500 µm and temporal 500 µm and 1500 µm, exhibited significant thinning (P<0.001).

CONCLUSION: At least six months after mild COVID-19 infection, significant thinning was seen in the temporal and superior quadrants of the macula, the temporal superior and temporal inferior regions of the RNFL and all measured areas of choroidal regions.