Corneal nerve changes in herpes zoster ophthalmicus: a prospective longitudinal in vivo confocal microscopy study

PURPOSE: To study the changes in corneal nerves and corneal sensitivity over a 6-month period in patients with herpes zoster ophthalmicus (HZO) compared with healthy subjects. METHODS: This was a prospective longitudinal study on patients with newly diagnosed HZO. In vivo confocal microscopy (IVCM) corneal nerve parameters and corneal sensitivity were measured and compared between eyes with HZO, contralateral eyes and controls at baseline, 2 and 6 months. RESULTS: Fifteen subjects with HZO and 15 healthy age and sex matched controls were recruited. HZO eyes revealed a reduction in corneal nerve branch density (CNBD) from baseline to 2 months (9.65 ± 5.75 vs. 5.90 ± 6.87/mm(2), p = 0.018), and decreased corneal nerve fibre density (CNFD) at 2 months when compared with control (p = 0.025). However, these differences resolved by 6 months. HZO fellow eyes demonstrated increased corneal nerve fibre area (CNFA), corneal nerve fibre width (CNFW) and corneal nerve fractal dimension (CNFrD) at 2 months compared with baseline (p = 0.025, 0.031, 0.009). There was no change in corneal sensitivity for both HZO affected and HZO fellow eyes from baseline or over time, nor was it different from sensitivity in controls. CONCLUSION: Corneal denervation was present at 2 months in HZO eyes, with an observed recovery by 6 months. HZO fellow eyes demonstrated increased corneal nerve parameters at 2 months, which could represent a proliferative response to nerve degeneration. IVCM is useful in monitoring corneal nerve changes, and is more sensitive in detecting nerve alterations than esthesiometry.