Purpose: The aim was to study the corneal endothelial count and morphology in patients with keratoconus by specular microscopy and to correlate them to the stage of keratoconus.
Methods: Forty eyes of 29 patients with keratoconus were enrolled in this cross-sectional cohort study. Corneal endothelium was evaluated using specular microscopy, and corneal topography and thickness data were obtained from Scheimpflug-based corneal tomography. Eyes were classified into stages 1 through 4 of keratoconus according to Amsler classification, using keratometry and pachymetry readings obtained from corneal tomography.
Results: Eleven eyes (27.5%) had stage 1, 17 eyes (42.5%) had stage 2, and 12 eyes (30%) had stage 3. Specular microscopy was not possible in stage 4. There was no statistically significant correlation between the stage of keratoconus and the endothelial cell density (ECD) (r = 0.018, P = 0.91), coefficient of variation (CV) (r = −0.011, P = 0.94), or percentage of hexagonality (6A) (r = −0.112, P = 0.51). When mild-to-moderate keratoconus (stages 1 and 2) was compared with severe keratoconus (stage 3), the difference was not significant regarding ECD (P = 0.1), CV (P = 0.3), or 6A (P = 0.4). However, there was a trend toward lower ECD and percentage of hexagonality, and a higher CV with advancing disease.
Conclusions: Up to stage 3, keratoconus does not significantly affect the corneal endothelium, as measured by specular microscopy. Eyes with stage 4 could not be studied by specular microscopy and may require other imaging methods such as confocal microscopy.