Analysis of Retinal Vessel Density using optical coherence tomography angiography in patients affected by COVID-19.

Abstract

Purpose : Patients affected by Coronavirus disease 2019 (Covid-19) suffer from a hypercoagulable state that may potentially affect the retinal and choroidal circulation. The aim of this study was to determine whether retinal and choriocapillaris vessel density (VD) as measured by optical coherence tomography angiography (OCTA) resulted abnormal in patients previously affected by Covid-19.

Methods : The right eye of sixty patients who tested positive for Sars-CoV-2 in a reverse transcription PCR assay were examined with structural optical coherence tomography (OCT) and OCTA. A control group of age-matched healthy subjects was selected for statistical comparisons. Raw OCT and OCTA images, acquired with TOPCON DRI OCT Triton, were exported using Topcon IMAGENET 6.0 software. 3D datasets were analysed to determine retinal thickness and VD in the 5 sectors of Early Treatment Diabetic Retinopathy Study (ETDRS).

Results : The images were gradable in 54 eyes (88%) on which the final analysis was conducted. The study and control group did not differed significantly for sex, intraocular pressure (IOP) and refractive error. Vessel density of the superficial capillary plexus did not differ between groups whereas VD of the deep capillary plexus (DCP) and choriocapillaris in the foveal ETDRS sector was significantly lower in the Covid-19 group compared to controls (P < 0.01). No significant difference was found in the VD’s recorded in any of the other 4 ETDRS sectors between groups. Within the COVID-19 group, subgroups were identified for therapies, underlying diseases and hospitalization. Based on therapies the lowest VD was recorded among patients treated with antiviral therapy compared to antiplatelet therapy (P < 0.01). No significant difference was found between patients affected by hypertension, diabetes or thyroid disease. A significantly reduced VD value was registered in patients admitted in ICU compared to asymptomatic (P < 0.01).

Conclusions : In patients with previous COVID, the VD of the retinal DCP and choriocapillaris measured with OCTA resulted decreased. The lowest values of VD were recorded in the eyes of patients who had undergone antiviral therapy and ICU-setting. Future studies are needed to further support our preliminary data that individuals with previous COVID might develop abnormalities of the retinal and choriocapillaris vasculature.

This is a 2021 ARVO Annual Meeting abstract.

 

Deep capillary plexus vessel density maps.