Mechanisms of visual impairment in COVID-19 and post-COVID syndrome: TRP channels as pathogenetic targets and objects of therapy

This article presents a literature review on visual impairments in COVID-19 and post-COVID syndrome and their possible pathogenesis. The data on possible cellular targets of SARS-CoV-2 in various damaged eye structures are discussed. The proposed approaches to the treatment of eye disorders in COVID-19 are reviewed. The main attention is given to the recently discovered family of cation channels — the channels with a transient receptor potential, or TRP channels, as possible targets of SARS-CoV-2 action on eye cells. The structure and properties of TRP channels, in particular their ability to act as receptors for temperature, pain and inflammation, and to participate in phototransduction, are examined. TRP channels are shown to be present in the anterior and posterior segments of the eye. The relationships are explored between TRP subfamilies, in particular TRPV1 channels, and various pathologies, such as dry eye syndrome, glaucoma, eye trauma, retinopathy, etc. Evidence is provided for a direct involvement of TRP channels in the pathogenesis of pulmonary pathology in COVID-19, and their role in the pathogenesis of many other diseases, including neuropathic and inflammatory pain, stroke, migraine, neurodegenerative disorders. The currently known pharmacological approaches targeting TRP channels are discussed. The paper highlights the importance of closely monitoring TRP channels activity, particularly TRPV1 ones, in assessing various COVID-19 manifestations, including eye infections.