Quantitative evaluation of keratoconus patients' corneal topography

Objective To evaluate corneal topography of keratoconus,and evaluate characteristics of the quantitative parameters.Methods Sixty-three keratoconus patients (Rabinowitz diagnosis standards) were examined on both eyes with Obscan Ⅱ topography.The recorded quantitative parameters were analyzed statistically.Sixty-four patients (64 eyes) with moderate or high myopia were selected as normal control and comparison analysis were made between them.Results The maximum keratometry of clinical keratoconus had significantly correlation with maximum posterior elevation,thinnest pachymetry,3-mm irregularity,5-mm irregularity (P ＜0.0001).Clinical and subclinical keratoconus eyes had higher maximum posterior elevation,3-mm irregularity,5-mm irregularity and thinner corneas compared with normal eyes.The distance from the thinnest point to the corneal center of clinical keratoconus group,subclinical keratoconus group and normal group was (0.76±0.42)mm,(0.66±0.38)mm and (0.61±0.29)mm,respectively.Most of the corneal thinnest point of clinical/subclinical keratoconus eyes was in the inferior tempus,the normal group was in the lmm ring region.Conclusions Obscan Ⅱ topography can make fully evaluation on comeal anterior and posterior face.Keratoconus can be diagnosed earlier by analyzing the quantitative index statistically. Key words: Corneal Topography;  Keratoconus;  Diagnose