Topographic Evaluation of Unilateral Keratoconus Patients

OBJECTIVES: To compare data obtained by Scheimpflug camera (Pentacam) from both eyes of unilateral keratoconus patients and normal controls. MATERIALS AND METHODS: This study was performed by retrospective chart review of 919 keratoconus patients. From these patients, 31 keratoconus eyes of 31 patients with unilateral keratoconus (Group 1), 31 normal fellow eyes of these patients (Group 2), and 30 right eyes of 30 normal controls (Group 3) were included in the study. Detailed ophthalmologic examination and Pentacam parameters at initial examination were analyzed and relationships between Groups 1, 2, and 3 were statistically evaluated. ROC curve analysis was also performed to determine the sensitivity and specificity of parameters that could be used to differentiate Group 2 from Groups 1 and 3. RESULTS: The mean age was 30.07±11.00 (15-60) in Group 1-2 patients and 32.33±9.30 (18-45) in Group 3 patients (p=0.392). In comparison of Pentacam data, there were statistically significant differences between Groups 1 and 2 in all parameters except corneal volume (p<0.05). Group 1 and Group 3 were significantly different in all evaluated parameters (p<0.05). Steep keratometry, flat keratometry, mean keratometry, and posterior elevation (PE) were statistically similar between Groups 2 and 3 (p>0.05), while the other evaluated parameters differed significantly (p<0.05). ROC curve analysis showed that the difference in corneal thickness between the apex and thinnest point, progression index, index of surface variance, index of height asymmetry and inferior-superior had the highest sensitivity and specificity in differentiating Group 2 from Group 3, while CCTapex, CCTmin, PE, and minumum radius had the highest sensitivity and specificity in differentiating Group 2 from Group 1. CONCLUSION: In patients with unilateral keratoconus, fellow eyes appear to not be completely normal. Thus, it is recommended that fellow eyes also be evaluated in every examination of unilateral keratoconus patients.