Multi-aspheric description of the myopic cornea after different refractive treatments and its correlation with corneal higher order aberrations

摘要

Background: To analyse the asphericity of the anterior corneal surface (ACS) for different diameters,and correlate those values with corneal higher order aberrations (cHOA) before and aftermyopic treatments with corneal refractive therapy (CRT) for orthokeratology and customized(CL) and standard laser (SL) assisted in situ keratomileusis (LASIK).Setting: Clínica Oftalmológica NovoVisión, Madrid, Spain.Methods: The right eyes of 81 patients (27 in each treatment group), with a mean age of29.94±7.5 years, were analysed. Corneal videokeratographic data were used to obtain cornealasphericity (Q) for different corneal diameters from 3 to 8 mm and cHOA root mean square(RMS) obtained from Zernike polynomials for a pupil diameter of 6 mm.Results: There were statistically significant differences in asphericity values calculated at differentcorneal diameters for different refractive treatments and their changes. The differencebetween asphericity at 3 and 8 mm reference diameters showed statistically significant correlationswith spherical-like cHOA that was also significantly increased after all procedures.Conclusions: The shift in corneal asphericity and the differences among different treatmenttechniques are more evident for the smaller reference diameters. These differences can bemuch reduced or even masked for a peripheral reference point at 4 mm from centre, which isused by some corneal topographers.