Keratoconus Asymmetry between Both Eyes Based on Corneal Tomography.

PURPOSE: To characterize the asymmetry between both eyes in patients with keratoconus based on corneal tomography. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Topographic characteristics of keratoconus among a sample of Jordanian patients.

AIM: To identify topographic characteristics of keratoconus in a Jordanian sample. METHODS: This study characterized 210 corneas affected with keratoconus presenting to Jordan University Hospital. Patients were diagnosed based on clinical examinations and Pentacam imaging. Eyes of males (n=101) were of a similar proportion to females (n=109). All of the 111 patients were affected bilaterally. Ages ranged between 13 and 44y with a mean age of 25.2y. RESULTS: Results revealed significant differences between males and females at the level of the flat curvature power, basement membrane thickness and size of the anterior chamber. Eyes were arranged in three groups based on severity levels: mild, moderate and severe determined by the mean curvature power (Km). Results show that the flat (K1) and steep (K2) curvature powers, corneal asphericity coefficient (QV), thinnest point, pachy apex and basement membrane thickness are significantly different among the three groups, but not the corneal and anterior chamber volumes. Morphological analyses, based on sagittal maps, show no differences in keratometric values between eyes with different sagittal patterns except for the vertical location of the pachy apex relative to the pupil center and the thinnest point. Eyes with the island front elevation map are significantly more affected than eyes with the U shape and the ridge pattern. CONCLUSION: All keratometric values measured except for corneal and anterior chamber volumes vary significantly with disease severity. The vertical pachy apex location correlates well with severity levels while the horizontal location seems to have no effect. Our study also indicates that front elevation maps may be a better predictor of the severity of keratoconus than sagittal maps.