Purpose: To estimate central corneal thickness (CCT) using a slitlamp biomicroscope and analyze its agreement with ultrasonic pachymetry.
Methods: Based on the clinical estimation of CCT on slitlamp examination, 133 eyes of 123 patients were assigned to 3 groups: CCT less than 500 μm, 500 to 600 μm, and greater than 600 μm. An average of three readings was obtained for each patient using an ultrasound pachymeter.
Results: The primary diagnoses at the time of presentation were glaucoma (42, 31.5%), corneal opacity (20, 15%), keratoconus (14, 10.5%), corneal edema (14, 10.5%), and postkeratoplasty eyes (8, 6%). Thirty-five (26.5%) eyes had no known ophthalmic diseases. There was an overall agreement of 86.5% in qualifying CCT into each of the 3 groups (kappa 0.76). The sensitivity and specificity of clinical estimation of CCT were found to be 96.26% (95% confidence interval [CI], 76.1%-94.2%) and 92.31% (95% CI, 78.7%-92.2%), respectively. The agreement was highest in patients with corneal edema (100%, kappa 1.00) and postkeratoplasty eyes (100%, kappa 1.00). The agreement was 82.9% (kappa 0.3) in normal eyes.
Conclusions: Estimation of CCT by slitlamp examination is a reliable tool in clinical practice. In our study, there was a substantial agreement between clinically estimated CCT and ultrasonic pachymetry. This agreement was higher in eyes with abnormal corneal thickness compared with normal eyes.