Fluorescein enhanced confocal microscopy in vivo for the evaluation of corneal epithelium

In vivo confocal microscopy is being increasingly used to evaluate corneal disorders. This study aimed to evaluate whether topical fluorescein application prior to in vivo confocal microscopy had any effect on the imaging characteristics of the corneal epithelium.

Confocal microscopy in vivo with Confoscan 3.0 (Vigonza, Italy) was performed on 22 corneas of 22 study patients before and 1 min after application of unpreserved 2% fluorescein solution on the cornea. Ten patients with normal corneal findings served as control. The quality of superficial epithelial (SE) visualization, the SE density, the image intensity and the presence of hyperreflective SE cells were evaluated.

Eleven patients had normal corneal epithelium (group 1), six had keratoconus (group 2) and five had overt epitheliopathy (group 3). The visibility of SE layers of all subjects appeared to be enhanced in the post-fluorescein images. There was a significant difference between the mean pre-fluorescein (857.2 + 319.4 cells/mm(2)) and post-fluorescein (1378.0 +/- 292.1 cells/mm(2)) SE densities of all study subjects (paired t-test, P < 0.001). Hyperreflective SE cells were more common in the post-fluorescein images of groups 2 (83.3%), and group 3 (80%) compared with group 1 patients (36.4%). These differences were not significant between the two consecutive corneal images of control patients who received unpreserved artificial tears instead of fluorescein.

Topical fluorescein application appears to enhance the visualization of the corneal epithelium. This technique may enable better evaluation of the corneal epithelium quantitatively and qualitatively in both normal subjects and patients with epithelial involvement.