Pain and sensation in dry eye disease

Abstract

AbstractThe recent definition of dry eye disease (DED) proposed by DEWS II includes, for the first time, neurosensory abnormalities in etiology of the disease. In DED, reduced tear secretion leads to inflammation and corneal nerve damage, which induce sensitization of corneal polymodal and mechano‐nociceptors, and an abnormal activity of cold thermoreceptors thus evoking pain and eye dryness sensations. Moreover, long‐term nerve damage and inflammation, modify the expression of ion channels involved in the stimulus detection (transduction) and excitability of ocular sensory neurons, changing their impulse firing and their connectivity at the CNS, which is the basis of neuropathic pain and dysesthesia referred to the eye surface in DED patients. These altered transducing and encoding ion channels are potential molecular targets to modulate neuropathic nerve activity in DED, currently under study. Although many subjective (surveys and questionnaires, corneal sensitivity measurement) and objective metrics (morphology and density of subbasal corneal nerves and immune cells, blink parameters, biomarkers in tears) are currently used to evaluate pain in DED patients, new instruments and procedures designed to obtain more reliable information on eye sensations and pain in DED need to be developed (SAF‐2017‐83674‐C2‐1‐R and 2‐R, Agencia Estatal de Investigación‐ERDF, Spain‐EU, and PROMETEO/2018/114, Generalitat Valenciana, Spain).