QST for Corneal Nerve Function

Inclusion Criteria:

Group 1: Stage I Neurotrophic Keratopathy (NK)

1. Clinical findings of Stage I NK

2. Decreased nerve density by IVCM

3. Decreased corneal sensation

Group 2: Stage II NK

1. Clinical findings of Stage II NK

2. Decreased nerve density by IVCM

3. Decreased corneal sensation

Group 3: Dry Eye Disease (DED)

1. Symptoms of DED at least 3 months

2. Presence of at least one of the following DED signs; tear film break-up time lowerthan 7, ocular surface staining more than +1 based on NIH scale

3. Normal or mildly effected corneal sensation

Group 4: Healthy Individuals

1. Absence of any ocular surface symptoms

2. Absence of ocular surface findings

3. Transparent and clear cornea

4. Normal corneal sensation

Group 5: NCP

1. Presence of neuropathic symptoms AND

2. Symptoms out of proportion to clinical findings AND

3. Nerve abnormalities detected by in vivo confocal microscopy

Exclusion Criteria:

1. History of diabetes

2. History of ocular surgery, corneal infection, or corneal injury within the last 3months

3. Systemic regular anti-inflammatory and/or steroid and/or immune-modulatory therapyin the last 3 months

4. Active ocular allergies

5. Any major psychiatric illness including bipolar, psychosis, obsessive-compulsivedisorder and major depression

6. Pregnancy

7. History of surgery within the last 3 months

8. History of , sarcoidosis, GVHD or collagen vascular disease

9. Allergic to benzalkonium chloride "BAK" (an eye-drop preservative)

10. Concurrent enrollment in other studies that in the opinion of the investigator willinterfere with the results of this study

11. Non-English speakers