SARS-CoV-2 infection appears to to cause overall ganglion cell layer (GCL) and inner plexiform layer (IPL) thinning, according to a study published in Photodiagnosis and Photodynamic Therapy.
Researchers enrolled 73 participants in a prospective, cross-sectional study consisting of patients with prolonged neurological symptoms following COVID-19 (study group; n=20; eyes, 34; 60% women; mean age, 47.9 years) and control individuals (n=23; eyes, 39; 65.2% women; mean age, 44.2 years). Participants underwent macular nerve fiber layer (m-RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), ganglion cell-inner plexiform layer (GCIPL), and inner retinal layer (IRL) thickness measurements via optical coherence tomography (OCT).
According to the report, thinning occurred in the inner superior quadrant of the mRNFL (P =.004) in study group participants. The most prominent thinning was measured in the GCL and IPL among these patients. The inner superior (P =.042), outer superior (P =.019), outer inferior (P =.030) and outer temporal (P =.002) GCL sectors were significantly thinner among the study group participants compared with control group individuals, along with inner superior (P =.019), outer superior (P =.041), inner temporal (P =.013), outer temporal (P =.001), and inner nasal (P =.022) IPL sector thicknesses. No significant differences were noted in choroidal parameters between the groups (P >.05).
Lung involvement was the most prominent parameter associated with thinning of the OCT layers followed by male sex. The loss of taste and smell also led to deterioration in some parameters.
No significant changes in central macular thickness (CMT), peripapillary retinal nerve fiber layer (pRNFL), and choroidal vascular index (CVI) parameters were observed in the post-COVID-19 period.
“[W]e detected an overall thinning of the GCL, IPL, and IRL layers with no significant change in CMT, pRNFL, and CVI in the post-COVID-19 period,” according to the researchers. “We commented on this effect as the direct or indirect effect of SARS-CoV-2, a neurotropic virus, on these layers, rather than a long-term neurodegenerative effect.”
Study limitations include a small sample size, the recruitment of volunteers as control group participants, and potential confounding due to a higher frequency of systemic diseases among the study cohort.
Kanra AY, Altınel MG, Alparslan F. Evaluation of retinal and choroidal parameters as neurodegeneration biomarkers in patients with post-COVID-19 syndrome: Evaluation of retinal and choroidal parameters as neurodegeneration biomarkers in patients with persistent post-COVID symptoms. Photodiagnosis Photodyn Ther. Published online September 6, 2022. doi:10.1016/j.pdpdt.2022.103108