Author: Gulfidan Bitirgen (Turkey)
Co-authors: Celalettin Korkmaz, Adil Zamani, Rayaz Malik
Purpose
Coronavirus disease 2019 (COVID-19) has been associated with a range of neurological manifestations including signs of central and peripheral nervous system involvement. A reduction in macular vessel density and alterations in retinal nerve fiber layer have also been demonstrated. In this study, we aimed to evaluate the changes in macular inner retinal layers in post-COVID-19 patients using spectral domain optical coherence tomography (SD-OCT).
Setting/Venue
This cross-sectional study was conducted at the Department of Ophthalmology, Necmettin Erbakan University Meram Medical Faculty Hospital, Konya, Turkey.
Methods
Thirty-three patients (18 male, 15 female) recovered from COVID-19 and 25 healthy subjects (13 male, 12 female) were included in the study. The number of persisting symptoms was identified using a questionnaire prepared in accord with the long-COVID guideline developed by the National Institute for Health and Care Excellence (NICE). All participants underwent SD-OCT (Heidelberg, Germany) imaging, and retinal layer segmentation was performed automatically. In addition to total macular volume (TMV) and central macular thickness (CMT), the average thicknesses of nerve fiber layer (NFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL) and total inner retinal layers (IRL) were measured at the central fovea (1-mm-diameter zone) and four quadrants (superior, inferior, nasal, temporal) of the parafoveal region (1-3 mm).
Results
The mean age was 44.5 ± 12.2 years in post-COVID-19 patients and 44.8 ± 10.3 years in the control group. There were no significant differences between the two groups for age (P=0.918) and gender (P=0.847). The mean time after the diagnosis of COVID-19 was 3.7 ± 1.6 months. Compared to healthy controls, post-COVID-19 patients had reduced NFL thickness at superior (P=0.001), inferior (P less than 0.001), temporal (P less than 0.001) and nasal (P=0.004) parafoveal regions with no significant differences in other retinal layers or TMV and CMT. The number of patients having at least one neurological symptom persisting over 4 weeks was 18/33 (55%). Patients with persisting neurological symptoms showed a reduction in NFL thickness at all four quadrants of the parafoveal zone (P less than 0.05 for all), while patients without persisting symptoms had a reduction only at the temporal (P=0.004) and inferior (P=0.002) parafoveal regions compared to healthy control participants. The total score of NICE questionnaire inversely correlated with TMV (ρ=-0.406; P=0.019), CMT (ρ=-0.383; P=0.028), GCL-central (ρ=-0.345; P=0.049), IPL-central (ρ=-0.347; P=0.048), and IRL-central (ρ=-0.374; P=0.032) and superior (ρ=-0.357; P=0.041) thicknesses.
Conlusions
In this study, we demonstrate a significant reduction in macular nerve fiber layer thickness in post-COVID-19 patients. Additionally, the severity of persisting symptoms is associated with the structural alterations of the inner retinal layers. Further investigation is required to better understand the natural course of inner retinal changes in post-COVID-19 patients.
Financial Disclosure
The authors have no financial relationship to disclose.
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