Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Ophthalmology

Purpose: To study the effect of COVID-19 on retinal structure and vasculature by Optical Coherence Tomography Angiography (OCTA) Patients and methods: 90 eyes of 45 patients who recovered & terminated their isolation from COVID-19 infections were compared to 90 eyes of 45 age and gender matched control. All the data regarding the COVID -19 infection were analyzed including clinical manifestations, CT chest, CBC and inflammatory markers as CRP, serum ferritin, D dimer test, and different therapies used. After meticulous ocular examination, we performed retinal OCTA to assess foveal thickness and vasculature. Primary outcomes parameters: comparing all OCTA parameters and detection of any retinal structure or vascular changes between cases and healthy group Results: Foveal avascular zone (FAZ) area was significantly larger in post COVID-19 cases (p=0.032). Post COVID-19 cases had significant lower vascular density (VD) values in all perifoveal quadrants of the superficial capillary plexus (SCP). They also had lower VD in the whole area, parafoveal, temporal & inferior perifoveal areas in the deep capillary plexus (DCP). There was a statistically significant negative linear correlation between CRP and temporal foveal SCP, (p=0.010), DCP whole area (p=0.003), para foveal DCP (p=0.038). Conclusion: This study reported decreased retinal VD and FAZ enlargement in COVID-19 patients compared to age- and sex-matched controls. The evaluation of retinal circulation represents a promising tool in the in vivo study of microvascular involvement in COVID-19 patients. Thus, OCTA could represent a valid biomarker of systemic vascular dysfunction post COVID-19

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