Corneal Endothelial Changes and the Different Stages of Keratoconus
Researchers performed this cross-sectional cohort study to examine the corneal endothelial count and morphology in patients with keratoconus by specular microscopy and to correlate them to the stage of keratoconus.
They enrolled 40 eyes of 29 patients with keratoconus and evaluated corneal endothelium using specular microscopy. The researchers obtained corneal topography and thickness data from Scheimpflug-based corneal tomography. They classified eyes into stages one through four of keratoconus according to Amsler classification, using keratometry and pachymetry readings obtained from corneal tomography.
According to the researchers, 11 eyes (27.5%) had stage one, 17 eyes (42.5%) had stage two and 12 eyes (30%) had stage three. Specular microscopy was not possible in stage four. There was no statistically significant correlation between the stage of keratoconus and the endothelial cell density (r=0.018; p=0.91), coefficient of variation (r=–0.011; p=0.94) or percentage of hexagonality (6A) (r=–0.112; p=0.51). When mild-to-moderate keratoconus (stages one and two) was compared with severe keratoconus (stage three), 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.
The researchers in this study found that up to stage three, keratoconus does not significantly affect the corneal endothelium, as measured by specular microscopy. Eyes with stage four could not be studied by specular microscopy and may require other imaging methods such as confocal microscopy.