Correlation between Central Corneal Thickness and Refractive Indices in a Laser Refractive Surgery Population

Purpose: To evaluate the correlation of central corneal thickness (CCT) with refractive error and keratometry in a group of patients eligible for laser keratorefractive surgery, which may serve as a bias in studies on intraocular pressure (IOP) measurement Methods: In a cross sectional observational study, the right eyes of 340 patients who underwent laser keratorefractive surgery during the year 2006 were included. The CCT was measured with ultrasound pachymetry. The refractive error, including sphere, cylinder, and spherical equivalent (SE), based on cycloplegic refraction. Keratometry (K) readings were derived from topography printouts. The correlation between refractive indices and CCT was investigated in all cases and also in refractive subgroups. Results: The mean±SD age of the patients was 28.7±7.7 years, ranging from 18 to 55 years. Seventy percent of the patients were female. The mean cycloplegic SE and CCT were -3.2±2.3 diopters (D) and 549.5±33.6 μm, respectively. A borderline negative correlation between age and CCT was observed (r=-0.1, P=0.05). None of the other parameters including gender, amount of refractive error (Sphere, cylinder and axis), and K-readings showed any significant correlation with CCT (P>0.05) in the whole group or different subgroups. Conclusion: In this refractive surgery population, refractive indices did not show any significant correlation with CCT. This suggests that the correlation between CCT and IOP which has been found by other investigations in similar populations is in accordance to our findings.