1. Ahmad Kheirkhah MD, Rodrigo Muller MD, Deborah Pavan-Langston MD, Andrea Cruzat MD, Pedram Hamrah MD Ocular Surface Imaging Center, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA. Financial Disclosure: None Support: NIH K08-EY020575 (Bethesda, Maryland, USA) (PH), Falk Medical Research Foundation (Chicago, IL) (PH), Research to Prevent Blindness Career Development Award (New York, NY, USA) (PH), Johnstone Research Foundation (Boston, MA) (DPL), Stevens Fund (Hoboken, NJ, USA) (DPL). Corneal Nerve Damage Due to Herpes Simplex Keratitis and Long-Term Corneal Nerve Regeneration

2. HSV Keratitis: Keratitis due to Herpes Simplex Virus. HSV Keratitis: The most common infectious cause of corneal blindness in the developed world. All corneal layers may be involved. HSV Keratitis is known to cause corneal nerve damage, resulting in neurotrophic keratopathy (NK) which may manifests as: -Reduced corneal sensation -Tear film dysfunction -Loss of epithelial integrity -Corneal ulceration and melting -Corneal perforation Herpes Simplex Keratitis

3. In Vivo Confocal Microscopy (IVCM): Normal CorneaNeurotrophic Keratopathy Subbasal Nerve FibersLoss of Subbasal Nerve Fibers Neurotrophic Keratopathy in HSV Keratitis 50 µm

4. Corneal nerve regeneration after acute injury has been shown for conditions such as corneal refractive surgery (LASIK and PRK). However, it remains unclear whether there is a regeneration of corneal nerves in cases with corneal involvement due to HSV keratitis in long-term follow-up. Nerve Regeneration in HSV Keratitis Purpose To evaluate the long-term alterations in corneal nerves in patients with HSV keratitis using IVCM.

5. Methods Prospective longitudinal study on 16 patients who had previous HSV keratitis. IVCM of the cornea was performed at the baseline and repeated after a follow-up of at least 2 years. Control Group: 15 eyes of 15 age-matched healthy normal controls.

6. In Vivo Confocal Microscopy  Confoscan 4 (Nidek) was used to evaluate subbasal nerves of the central cornea in both affected and non-affected eyes as well as in the control group.  Three representative IVCM images per eye were evaluated by 2 masked observers using NeuronJ software to measure corneal subbasal nerve density.

7. In Vivo Confocal Microscopy Corneal Subbasal Nerves Nerve Density (mm/mm 2 ) Subbasal Nerves Subbasal Dendritic Cells Nerve Tracing by NeuronJ

8. Results HSV Group: 16 patients (10F/6M), mean age: 64 ± 17 years. Control Group: 15 patients (10F/5M), mean age: 59 ± 17 years (P=0.67). HSK: All had acute HSV keratitis at 2 months to 9 years (median: 2.3 years) prior to enrollment. Two patients had bilateral involvement, and 14 had unilateral involvement. Corneal Findings: Stromal scar or haze in the affected eyes (n=18), and no clinical corneal involvement in the contralateral non-affected eyes (n=14). Mean Follow-up: 37.3 ± 6.9 months (range, 29-46 months).

9. mm/mm 2 Nerve Density: Controls > Non-affected Eyes > Affected Eyes P<0.001 Baseline Controls Non-affected Eyes Affected Eyes

10. P=0.002 Follow-up Affected Eyes: Significant Increase in Nerve Density during Follow-up mm/mm 2 Baseline Follow-up

11. P=0.88 Follow-up Non-affected Eyes: No Significant Change in Nerve Density during Follow-up mm/mm 2 Baseline Follow-up

12. Conclusion Patients with neurotrophic cornea due previous HSV keratitis show significant regeneration of corneal nerves during the long-term follow-up. Therefore, it may expected to have some improvement of the associated ocular surface disease during the long-term follow-up. Contact: Ahmad_Kheirkhah@meei.harvard.edu, Pedram_Hamrah@meei.harvard.edu