Towards a better understanding of chronic ocular pain

Dry eye symptoms are one of the leading complaints in ophthalmology. They include visual disturbance, various types of symptoms and variable intensity of pain and discomfort that may become chronic or permanent and thus affect significantly the quality of life of patients. Nevertheless, the pathophysiological mechanisms of ocular surface pain remain largely unknown. A better clinical characterization of chronic ocular pain and an understanding of the molecular and cellular mechanisms involved are crucial issues for developing effective management and therapeutic strategy to alleviate ocular pain. In this review, we first describe the nociceptive corneal nerve pathways and the classification of corneal sensitive receptors neurons. The second part of this review gives an update of the preclinical and clinical data related to the inflammatory processes linked to inflammatory ocular pain. The last section describes the various diagnostic tools used in the clinic to evaluate corneal sensitivity and corneal inflammation.