Clinical findings:
(1) The dry eye may be unilateral or bilateral.
(2) History of neurologic disease and/or other neurologic manifestations.
(3) Conditions interfering with REM sleep can interfere with lacrimal signals.
Neurologic causes of dry eye:
(1) lesions in the limbic area or hypothalamus (central)
(2) loss of efferent secretagogue innervation
(3) afferent denervation impacting reflex activity
Loss of efferent innervation may occur with:
(1) lesions of the pregeniculate facial nerve
(2) botulinum toxin injection
(3) Riley-Day syndrome
(4) lesions of the pontobulbar pathway
(5) lesions to the first or second trigeminal nerves
(6) lesions to other nerves (superficial petrosus, sphenopalatine, etc)
Afferent denervations include:
(1) postsemilunar trigeminal damage
(2) contact lenses
(3) LASIK procedure
(4) corneal transplantation
(5) infectious or noninfectious keratitis
