Corneal topographic characteristics of persons seeking laser refractive surgery

AIM OF THE STUDY: To evaluate the prevalence and correlation of corneal topographic characteristics in clinically normal persons who were rejected for Laser refractive surgery based on Orbscan II analysis. METHODS: From a total of 1518 clinically normal refractive surgery candidates, the Orbscan maps of 278 eyes of 144 patients who were rejected for the surgery based on corneal topography alone were analyzed. RESULTS: The most common anterior and posterior elevation pattern was the irregular ridge (44%) and (55%) respectively. In axial keratometry, both the symmetric (29%) and asymmetric bowtie (29%) patterns were equally common. In pachymetric classification, the round pattern (40%) was the commonest. Mean (SD) of the Mean astigmatism was 1.4 D (1.1). Mean (SD) of Sim K Max was 47.2 D (2). Mean (SD) of 3mm and 5 mm irregularity were 1.3 D (0.7) and 1.9 D (0.8) respectively. Mean (SD) of thinnest pachymetry was 500 microns (46.5) and the range was from 386 to 623 microns. The thinnest site of the cornea was commonly located in the inferotemporal region in 94 eyes (33.8%). 142 eyes (51%) had a ratio of radii of anterior BFS to posterior BFS ≥ 1.23. 119 eyes (43%) had a power of Posterior BFS >55 D. 171 eyes (62%) had a Sim K Max > 47.2 D. 90 eyes (32.4%) had a thinnest pachymetry 1.16.The correlation between steep corneas (Sim K Max > 47.2 D), thin corneas (thinnest pachymetry 55 D was statistically significant (P