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Ocular neuropathic pain is a spectrum of disorders of ocular pain which are caused by damage or disease affecting the nerves. Ocular neuropathic pain is frequently associated with damaged or dysfunctional corneal nerves, but the condition can also be caused by peripheral or centralized sensitization. The condition shares some characteristics with somatic neuropathic pain in that it is similarly associated with abnormal sensations or pain from normally non-painful stimuli , but until recent years has been poorly understood by the medical community, and frequently dismissed by ophthalmologists who were not trained to identify neuropathic pain as a source of unexplained eye pain beyond objective findings noted on slit-lamp examination.
This condition is frequently associated with dry eye disease since sensations of dryness and burning in the eye are a common symptom of both neuropathic eye pain and dry eye, but ocular neuropathic pain should be considered as a disease in its own right. Neuropathic pain patients may have little or no signs of aqueous dry eye, and frequently respond poorly to conventional dry eye treatments. Unlike conventional dry eye disease, there may be little or no sign of ocular surface damage, , however patients may also have symptoms of dry eye but with pain symptoms that are out of proportion to the dry eye presentation.
The experience of painful sensations in this condition can vary widely, reflecting a variety of causal factors such as: types of noxious stimuli causing insult to ocular surface nociceptors, the types of corneal sensory receptors affected, , the extent of the inflammatory responses, and the type or types of disorders and damage affecting the nervous system.