Specular microscopic observation of human corneal epithelial abnormalities.

The diameter of the cone lens of the specular microscope was enlarged from its original size of 3.5 mm to 6.0 mm. This modification enabled the authors to take clear pictures of the corneal epithelium with a specular microscope (SM) contact lens, because tears could be excluded from the photographic field by exerting even pressure on the cornea. The normal corneal epithelium showed three kinds of cells with no abnormally shaped or reflex cells. As spindle-shaped cells were mainly observed in keratoconus patients, post-penetrating keratoplasty patients, and postepikeratophakia patients, this suggests that these cells may be an indicator of wound healing. Large cells were observed in diabetic aphakic patients, aphakic extended-wear soft contact lens wearers, and aphakic patients using 0.5% indomethacin eye drops; thus, the presence of large cells may indicate suppressed metabolism and mitosis. Colonies of small cells were observed in keratoconjunctivitis patients. Cells with nuclei and irregular cell patterns were observed in all diseased conditions. There are several common abnormal patterns in the corneal epithelium that are observable under the specular microscope. Modified specular microscopic observation can detect these subtle alterations at the cellular level.