Corneal pain without stain: is it real?

Clinicians often encounter patients who report corneal pain suggestive of dry eye disease, yet lack equivalent signs. These patients represent a diagnostic and therapeutic challenge that is more easily dismissed than addressed. We review the physiology of pain and the pathophysiological mechanisms of neuropathic corneal pain and speculate on the mechanisms of certain etiopathogenic triggers, such as LASIK, severe dry eye disease, and Sjogren syndrome. Recognizing corneal neuropathic pain as a disease in its own right is the first step toward developing more effective treatments for these severely disabled and presently inadequately served patients.