Relationship between minimum corneal thickness and refractive state, keratometry, age, sex, and left or right eye in refractive surgery candidates

PURPOSE: To evaluate the relationship between the thinnest point in corneal thickness and the refractive state, keratometry, age, sex, and the ocular side. SETTING: Eye clinics in Germany and Austria and the Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. DESIGN: Cross-sectional study. METHODS: Medical records of refractive surgery candidates from 2006 to 2010 were reviewed. Univariate variance analysis, covariance analysis, Bravis-Pearson correlations, Spearman rank correlations, and t tests were performed to analyze the relationship between the thinnest point in corneal thickness and the biometric parameters. RESULTS: The study evaluated 4600 eyes. The mean thinnest point in corneal thickness was 549 μm ± 33 (SD). Refractive state, mean keratometry, and age had a statistically significant impact on the thinnest point in corneal thickness. The mean thinnest point in corneal thickness was 548 ± 33 μm in myopia, 555 ± 34 μm in hyperopia, and 553 ± 35 μm in high astigmatism, with a statistically significant difference between hyperopic eyes and myopic eyes (P<.001). No correlation was found between the thinnest point in corneal thickness and sex or ocular side. Refractive state (r = 0.07, P<.001) and age (r = 0.05, P<.001) showed a positive correlation and keratometry (r = -0.09, P<.001) a negative correlation with the thinnest point in corneal thickness. CONCLUSIONS: Refractive state, mean keratometry, and age had a statistically significant, although marginal impact, on the thinnest point in corneal thickness. Sex and the ocular side had no effect.