Evaluation of the influence of corneal biomechanical properties on the central corneal curvature after a SUPRACOR procedure

Abstract

PurposeSUPRACOR™, performed with the Technolas Excimer Workstation 217P (Bausch + Lomb Technolas), creates a small zone of high refractive power in the central cornea, the « bump », to facilitate near focus. The aim of this study is to evaluate the influence of corneal biomechanics on this « bump ».MethodsThis retrospective study included 46 eyes of 23 patients. The Supracor ablation pattern was applied, to create hyperprolate shape resulting about 2 D near addition. The periphery was treated with hyperopic ablation in a 6 mm zone, using 9.5 mm suction ring, under 120 µm flap created by the IntraLase FS60 femtosecond laser (AMP, USA). Every patient underwent a corneal topography (Pentacam, Oculus, Germany) before and 1 month after surgery to evaluate the importance of the “bump”, and a biomechanical evaluation with the Ocular Response Analyser (ORA, Reichert, NY). CH (Corneal Hysteresis) and CRF (Corneal Resistance Factor) were evaluated. Spearman's rank correlation coefficient was used to analyze the relationship between the parameters of the ORA and the « bump ».ResultsThe mean patient age was 55.5 ± 3.94, ranging from 50 to 62 years. Pre‐operative spherical equivalent were 1.57 ± 0.77 D. Mean corneal thickness was 548 ± 44 µm. CH and CRF were respectively 10.53 ± 1.63 mmHg and 10.90 ± 2.12 mmHg. Mean “bump” was 2.25 ± 0.98 D, ranging from 0.50 to 4.64 D. A correlation was found between the CH and the bump (r = 0.34; p = 0.022) and also between the pachymetry and the bump (r = 0.45; p = 0.004). A strong correlation was found between corneal thickness and the CH (r = 0.62; p = 0.001).ConclusionsIn this study, the “bump” is correlated with the corneal thickness and the CH. The corneal thickness appears to be sufficient to predict the “bump” in hyperopic patients undergoing Supracor. These results should be confirmed in a larger sample of patients.