Abstract
Purpose: :
To analyze the morphology of corneal epithelial cells and keratocytes by in vivo confocal microscopy in patients with herpes simplex keratitis (HSK) as associated with corneal innervation.
Methods: :
A prospective study was performed in patients with HSK (n=28). Corneal sensation was measured bilaterally in patients, as well as in 10 normal eyes, with a Cochet-Bonnet aesthesiometer. Patients were grouped into normal (>5.5 cm), mild (>2.5 to 5.5cm) and severe ( 2.5 cm) loss of sensation. The central cornea of all patients and controls were imaged bilaterally with a Confoscan 4 IVCM. Two masked observers reviewed the images in regards to morphology and density of the superficial and basal epithelial cells, as well as stromal keratocytes. Changes were correlated to corneal sensation, number of nerves, and total length of nerves per image.
Results: :
There was a significant and gradual decrease in the density of superficial epithelial cells in HSK eyes, with 917 cells/mm2 in eyes with severe sensation loss and 1450 cells/mm2 in control eyes (P = 0.008). Superficial epithelial cell size was 3-fold larger in HSK eyes (1034 µm2) as compared to contralateral or normal eyes (350 µm2; P = 0.003). A significant number of hyperreflective desquamating superficial epithelial cells were present in HSK eyes with normal (6%), mild (29%) and severe (52%) loss of sensation, but were absent in controls. The density of basal epithelial cells, anterior keratocytes, and posterior keratocytes did not show statistical significance between patients and controls. Changes in superficial epithelial cell density and morphology correlated strongly with total nerve length, number, and corneal sensation. Scans of contralateral eyes did not show any significant epithelial or stromal changes as compared to controls.
Conclusions: :
In vivo confocal microscopy reveals profound HSK-induced changes in the superficial epithelium, as demonstrated by increase in cell size, decrease in cell density, and squamous metaplasia. We demonstrate that these changes strongly correlate with changes in corneal innervation.
Keywords: keratitis • imaging/image analysis: clinical • cornea: epithelium