Use of Imaging Technology to Assess the Effect of COVID-19 on Retinal Tissues: A Systematic Review

Abstract

Purpose To evaluate the effect of COVID-19 on retinal tissues by conducting a systematic review and meta-analysis of the current literature. Background The novel coronavirus disease is not yet well understood. The orbit provides a window into the body's microvasculature, and as such, it is a non-invasive opportunity to analyse the systemic circulation in vivo. By analysing the current literature, we test the hypothesis that non-invasive imaging of the retina could provide insight into the effect of COVID-19 on the retinal microvasculature. Methods For this systematic review and meta-analysis, we screened PubMed databases and LitCOVID19 using the search criteria: (OCTA or Optical Coherence Tomography Angiography) AND (COVID-19 or corona or SARS-CoV-2) AND (retina or fundus). Databases were searched on 11 January 2022. The primary study outcomes were studies that utilised OCTA to analyse the retina; secondary outcomes involved studies that involved other imaging modalities such as OCT, fundus photography, and fundus autofluorescence. Findings The total number of studies included in this review was 32. Optical coherence tomography angiography scans show reduced central retinal vascular density, a thinner ganglion cell layer, a thicker retinal nerve fibre layer, and an enlarged foveal avascular zone. Optical coherence tomography scans demonstrate a thicker central macular thickness and other changes to the macula, ganglion cell, and inner nuclear layers. Many fundus photographs depicted cotton wool spots, microhaemorrhages, and vascular occlusions. Non-invasive imaging technology has demonstrated that COVID-19 can profoundly affect the retina. Therefore, there is a requirement for long-term follow-up of COVID-19 patients to assess whether the retinal damage caused by COVID-19 is reversible. Supplementary Information The online version contains supplementary material available at 10.1007/s40123-022-00509-8.

SARS-CoV-2 neurovascular invasion supported by Mendelian randomization

“…Previous studies have pointed to retinal involvement in COVID-19, such as central retinal artery/vein occlusion and acute macular neuroretinopathy, which can directly damage vision [ 10 , 11 , 18 ]. RGCs are particularly susceptible to SARS-CoV-2 infection, which can directly cause acute pathological changes and increase overall retinal thickness due to immune cells infiltration [ 19 , 20 ].…”

“…RGCs are particularly susceptible to SARS-CoV-2 infection, which can directly cause acute pathological changes and increase overall retinal thickness due to immune cells infiltration [ 19 , 20 ]. Mechanistically, the viral infection induces a procoagulant state and endothelial inflammation with recruitment of inflammatory cells, resulting in micro-thrombosis and retinal thickening in the early stage [ 10 , 21 – 23 ].…”

“…Changes in mGCC thickness measured via OCT can provide additional direct and visible evidence of the effect of SARS-CoV-2 on retinopathy. However, studies of SARS-CoV-2 retinopathy were mostly observational studies and case reports that were controversial due to various confounders from acquired environmental exposure [ 10 , 11 ].…”

Multicenter and multimodal imaging study reveals rare fundus lesions in patients after SARS-CoV-2 infection

“…A review in 2022 suggested the potential involvement of the posterior segment in SARS-CoV-2, either in the initial or later stage 9 . However, few studies have systematically described the manifestations of the posterior segment of the eye by multimodal imaging study 10 .…”

“…the initial or later stage 9 . However, few studies have systematically described the manifestations of the posterior segment of the eye by multimodal imaging study 10 .…”