Keratoconus Asymmetry between Both Eyes Based on Corneal Tomography

To characterize the asymmetry between both eyes in patients with keratoconus based on corneal tomography.

All patients with keratoconus who presented to the eye clinic at Jordan University Hospital between January 2008 and November 2011 were included in the study. Using computerized corneal tomography, the keratometric values and indices of both eyes of participants with keratoconus and normal controls were compared. For both eyes to be considered symmetrical, the difference between the mean curvature power (Km), flat curvature power (K1), or steep curvature power (K2) in both eyes was equal to or <2.5 diopters, and the difference between the thinnest corneal points was equal to or <25.0 μm between both eyes.

Ninety-eight patients with keratoconus and 49 normal participants were evaluated. The mean age of the participants was 26.3 ± 6.6 years. The results showed two populations of patients with keratoconus: one with asymmetrical corneas who were more affected by the disease and another with symmetrical corneas. As the disease severity increased, the differences between the two eyes increased for patients with the asymmetrical form, while both corneas of patients with the symmetrical form were similar.

Corneal tomography identified two forms of keratoconus: symmetrical and asymmetrical. The latter tended to be more severe and occurred in a younger age group. Questions remain about whether the two keratoconic forms are specific to the Middle Eastern population and whether there are ethnic or demographic forms of the disease.