COVID-19 may generate small fiber neuropathy in the ocular surface, sharing similar symptoms and morphological indicators with dry eye disease (DED) and diabetic neuropathy, according to a study published in the Ocular Surface.
Investigators sought to characterize the association between SARS-CoV-2 infection and small fiber neuropathy in the cornea. The observational retrospective study included 23 patients (18 women, 5 men) who had overcome COVID-19 between March and December 2020, and 46 uninfected volunteers.
All participants underwent vivo confocal microscopy to obtain images of corneal subbasal nerve fibers in order to evaluate the presence of neuroma-like structures, axonal beadings and dendritic cells. The investigators used the Ocular Surface Disease Index (OSDI) questionnaire and Schirmer tear test as indicators of Dry Eye Disease (DED) and ocular surface pathology.
The research team found that 21 out of 23 patients (91.31%) had alterations of the corneal subbasal plexus and corneal tissue consistent with small fiber neuropathy. The team noted that images from healthy participants did not show significant nerve fiber or corneal tissue damage.
In total, 8 patients reported increased sensations of ocular dryness following COVID-19 infection and had positive DED indicators. Beaded axons were found in 82.60% of patients, typically in those reporting ocular irritation symptoms. Neuroma-like images were found in 65.22% of patients, occurring more frequently in those with OSDI scores of >13. Dendritic cells were found in 69.56% of patients and occurred more frequently in younger asymptomatic patients.
“The presence of morphological alterations in patients up to 10 months after recovering from Sars-CoV-2 infection points to the chronic nature of the neuropathy,” according to the study. “To our knowledge, this is the first report of signs of corneal neuropathy in patients that have overcome COVID-19.”
Barros A, Queiruga-Piñeiro J, Lozano-Sanroma J, et al. Small fiber neuropathy in the cornea of Covid-19 patients associated with the generation of ocular surface disease. Ocul Surf. Published online November 12, 2021. doi:10.1016/j.jtos.2021.10.010