[Morphometric analysis of corneal epithelium in normal subjects and soft contact lens wearers]

It is difficult to perform specular microscopic observation of the corneal epithelium in vivo due to the interference of light scattering by the tear film layer. In this study, we clearly observed the morphology of superficial corneal epithelial cells with a specular microscope contact lens that has the same refractive index as the corneal tissue. A total of 61 corneas from normal subjects and 21 corneas from soft contact lens wearers who had worn their lenses on a regular daily basis were studied using a specular microscope to take pictures of the corneal epithelium. The pictures were then analyzed with a computer-assisted morphometric analysis system. In normal subjects, the mean epithelial cell area and corresponding mean coefficient of variation (CV) were 618 +/- 97 microns 2 and 30.7 +/- 5.0% respectively. There was a significant correlation between the mean epithelial cell area and age in male group (p < 0.05) but not in the female group; whereas a significant correlation existed between CV and age in the female group only (p < 0.05). In the soft contact lens group, the mean epithelial cell area was 675 +/- 143 micron 2 and the CV was 29.6 +/- 6.0%. Compared to the corneal epithelium of normal subjects, the epithelial cell area and CV in the soft contact lens group was not significantly different; however, abnormal morphologic patterns in the corneal epithelium appeared more frequently. Our study showed that modified specular microscopy is a noninvasive and clinically valuable method by which to assess subtle alterations in the corneal epithelium that are barely detectable with routine slit lamp biomicroscopy.