Heidelberg retina tomograph 2 rostock corneal module

Morphology of subbasal nerve fibers in the area of epithelial defects was observed by IVCM performed using the Heidelberg Retina Tomograph II Rostock Corneal Module (Heidelberg Engineering GmbH, Heidelberg, Germany) as previously described [11 (link)]. Bilateral corneal sensation was tested by using a Cochet-Bonnet aesthesiometer (Luneau Ophthalmology, Paris, France). The central cornea was stimulated vertically with nylon filament, starting from 60 millimeters in length and gradually decreasing until corneal sensation appeared, where corneal sensation was defined as the corneal perception of the longest silk line. The test was repeated twice, and the average length was obtained.

Laser scanning in vivo confocal microscopy was performed in all subjects with the Heidelberg Retina Tomograph II Rostock Corneal Module (Heidelberg Engineering GmBH, Heidelberg, Germany). All eyes were anesthetized with a drop of 0.4% benoxinate hydrochloride (Chauvin Pharmaceuticals, Surrey, UK). Viscotears (Carbomer 980, 0.2%; Novartis, North Ryde, NSW, Australia) was used as a coupling agent between the applanate lens cap and the cornea. During the examination, all subjects were asked to fixate on a distance target aligned to enable examination of the central cornea. The central corneal thickness may increase with time after PK [16 (link), 17 (link)]. For brevity, we referred to this variable as “the number of keratocytes.” Three randomly chosen images per subject were analyzed and statistically compared.