QST for Corneal Nerve Function

This study is designed to learn more about the impact different types of stimuli, such as heat, cold and vibration, can have on ocular pain response. This is called quantitative sensory testing (QST). Most procedures being performed in this study, except the QST, are standard of care which means they are performed during the participant's routine eye examination.

Inclusion Criteria:Group 1: Stage I Neurotrophic Keratopathy (NK)Clinical findings of Stage I NKDecreased nerve density by IVCMDecreased corneal sensationGroup 2: Stage II NKClinical findings of Stage II NKDecreased nerve density by IVCMDecreased corneal sensationGroup 3: Dry Eye Disease (DED)Symptoms of DED at least 3 monthsPresence of at least one of the following DED signs; tear film break-up time lower than 7, ocular surface staining more than +1 based on NIH scaleNormal or mildly effected corneal sensationGroup 4: Healthy IndividualsAbsence of any ocular surface symptomsAbsence of ocular surface findingsTransparent and clear corneaNormal corneal sensationGroup 5: NCPPresence of neuropathic symptoms ANDSymptoms out of proportion to clinical findings ANDNerve abnormalities detected by in vivo confocal microscopyExclusion Criteria:History of diabetesHistory of ocular surgery, corneal infection, or corneal injury within the last 3 monthsSystemic regular anti-inflammatory and/or steroid and/or immune-modulatory therapy in the last 3 monthsActive ocular allergiesAny major psychiatric illness including bipolar, psychosis, obsessive-compulsive disorder and major depressionPregnancyHistory of surgery within the last 3 monthsHistory of , sarcoidosis, GVHD or collagen vascular diseaseAllergic to benzalkonium chloride "BAK" (an eye-drop preservative)Concurrent enrollment in other studies that in the opinion of the investigator will interfere with the results of this studyNon-English speakers