COVID-19 infection may lead to small fiber neuropathy on ocular surface: Study

Spain: New research discovered that Sars-CoV-2 infection may cause small fiber neuropathy on the ocular surface, with symptoms and morphological characteristics similar to dry eye disease (DED) and diabetic neuropathy. The findings of this study were published in the Ocular Surface journal.

This work was conducted by Alberto Barros and the team with the objective to investigate the relationship between Sars-CoV-2 infection and small fiber neuropathy in the cornea as detected by in vivo corneal confocal imaging.

This observational retrospective analysis included 23 patients who have overcome COVID-19. In addition, 46 uninfected volunteers were selected and analyzed as a control group. All participants were evaluated using in vivo confocal microscopy to capture pictures of ocular sub-basal nerve fibers to look for neuroma-like formations, axonal beadings, and dendritic cells. As indications of DED and ocular surface pathology, the Ocular Surface Disease Index (OSDI) questionnaire and Schirmer tear test was utilized.

The main findings of this study are as follow:

1. Twenty-one patients (91.31%) had corneal sub-basal plexus and corneal tissue changes compatible with small fiber neuropathy.

2. Images from healthy patients revealed no evidence of nerve fiber or ocular tissue injury. Eight individuals with positive DED signs reported increased ocular dryness following COVID-19 infection.

3. Beaded axons were discovered in 82.60% of the cases, mostly in patients who reported ocular irritation symptoms.

4. Neuroma-like images were seen in 65.22% of patients, with higher rates in those with OSDI scores greater than 13.

5. Dendritic cells were detected in 69.56% of patients, with younger asymptomatic individuals having a higher prevalence.

6. The existence of morphological changes in individuals up to 10 months after recovery from Sars-CoV-2 infection indicates that the neuropathy is persistent.

In conclusion, this is the first report of corneal neuropathy symptoms in people who have overcome COVID-19. The existence of morphological changes in individuals up to 10 months after recovery from Sars-CoV-2 infection indicates that the neuropathy is persistent.

Reference:

Barros A, Queiruga-Piñeiro J, Lozano-Sanroma J, Alcalde I, Gallar J, Fernández-Vega Cueto L, Alfonso JF, Quirós LM, Merayo-Lloves J. Small fiber neuropathy in the cornea of Covid-19 patients associated with the generation of ocular surface disease. Ocul Surf. 2021 Nov 12;23:40-48. doi:10.1016/j.jtos.2021.10.010.