Purpose
The healthy eye of a unilateral keratoconus (KC) patient is an ideal model to study pre-ectatic parameters of the cornea. These eyes are accepted to be susceptible to develop KC with sufficient follow-up time. Because of this reason, detailed evaluation of these eyes may help us to better understand pre-ectatic topographic risk factors. In this study, we have evaluated topometric indices of unilateral KC patients with a Scheimpflug camera and compared these results with KC eyes and healthy controls.
Methods
A retrospectively chart review was performed. The differential diagnosis of the eyes with unilateral KC, form fruste KC and KC was made with Scheimpflug camera parameters. The results were compared with healthy, form fruste and KC eyes. Corneal topography, thickness map, curvature maps, anterior-posterior elevation maps, and enhanced ectasia display results were compared. P value less than 0.05 was considered statistically significant
Results
Three hundred and fifty patients were diagnosed with keratoconus. In our cohort, 4.85 % of our patients had unilateral keratoconus (17 patients). These patients had normal topography and elevation maps in one eye (Group-1) and clinically significant KC in the fellow eye. Forty patients had form fruste keratoconus in one eye (Group-2) and clinically significant KC in the fellow eye. Right eyes of 25 healthy refractive surgery candidates were randomly selected as controls (Group-3). There were statically significant differences in minimum corneal thickness, central corneal thickness, minimum and maximum average progression indexes, enhanced ectasia display deviations (Dp, Dt, D) and index of highest asymmetry parameters between 3 groups (p<0,05). The difference between minimum, maximum and average pachymetry progression indices of normal eyes of unilateral keratoconus group and healthy controls was statistically significant (p<0,05).
Conclusions
Our study demonstrates that the healthy eyes of patients with unilateral KC demonstrated normal tomographic and elevation pattern. Enhanced ectasia scores of these eyes were also within normal limits. Interestingly minimum, maximum and average pachymetry progression indices of healthy eyes with unilateral KC were statistically significantly different from that of healthy controls.
Keywords: 574 keratoconus