Investigating the Neurological and Retinal Manifestations of Long COVID-19 Among Adults in Kano and Lagos: An Optical Coherence Tomography Angiography Study

Post-acute sequelae of COVID-19 (long COVID) are increasingly recognized to include neurological and vascular complications, with emerging evidence of retinal microvascular changes detectable by optical coherence tomography angiography (OCTA). In Nigeria, where COVID-19 affected millions across urban centers, the ocular and neurological sequelae of long COVID remain entirely uninvestigated. This study characterizes the retinal microvascular, structural, and neurological manifestations of long COVID among adults in Kano (North West) and Lagos (South West) using OCTA and neuroimaging-correlated analysis. A prospective cross-sectional design will recruit 200 adults with confirmed long COVID (defined as persistent symptoms beyond 12 weeks) and 200 age-, sex-, and comorbidity-matched controls. OCTA will assess superficial and deep retinal capillary plexus vessel density, foveal avascular zone area, and choriocapillaris flow. These will be correlated with cognitive assessments, visual field testing, and biomarkers of endothelial inflammation. The study will generate the first dataset of COVID-19-related retinal OCTA changes in West African adults, making an original contribution to the global long COVID phenotyping literature. Findings will be disseminated to the Nigeria Centre for Disease Control and international COVID-19 research consortia to advance understanding of ocular complications in post-COVID care. Keywords: long COVID, OCTA, retinal microvascular, neurological manifestations, Nigeria