• Comprehensive Ophthalmology, Cornea/External Disease

    Review of: Small fiber neuropathy in the cornea of Covid-19 patients associated with the generation of ocular surface disease

    Barros A, Queiruga-Piñeiro J, Lozano-Sanroma J, et al. The Ocular Surface, January 2022

    This is the first report of small fiber neuropathy on the ocular surface linked to the SARS-CoV-2 virus, with symptoms and morphologic landmarks similar to those seen with diabetic neuropathy and dry eye disease (DED).

    Study design

    This observational retrospective study conducted in Spain included 23 patients with a prior history of COVID-19 and a control group of 46 uninfected participants. In vivo confocal microscopy (IVCM) images were obtained from both groups. Various IVCM parameters relating to corneal nerve fiber density, length, branch density, area, width neuromas, beaded axons, and dendritic cell (DC) density were evaluated. The Schirmer tear test and the Ocular Surface Disease Index (OSDI) questionnaire were used to measure DED and ocular surface pathology.


    The IVCM imaging revealed small fiber neuropathy features, including corneal cell infiltration and morphologic alterations of the corneal subbasal plexus, in 91% of post–COVID-19 patients. None of the patients in the control group showed any of these features, and only 4% had identifiable neuromas. Patients with COVID-19 showed greater DED severity than the control population.


    Moving forward, IVCM evaluations in post–COVID-19 patients would benefit from larger sample sizes and longer-term data. Additionally, the association between inflammatory response mediators, such as dendritic cells, and asymptomatic young SARS-CoV-2 virus carriers need to be studied further.

    Clinical significance

    The results of this study add new evidence to the literature for the use of IVCM technology in the diagnosis and follow-up of post–COVID-19 syndromes or complications, and its utility for assessing small fiber neuropathies.