[Optimization of an individualized LASIK surgery. Geometric ray tracing model]

To develop an objective calculation method that is able to provide a customized surgical correction that allows the patient to reach the emmetropia and the maximum visual acuity after the surgery.

The study included 187 eyes with myopia or myopic astigmatism that underwent LASIK. The optical characterization of each eye was developed by a complete theoretical model based in Le Grand eye, in which the measured values of radii and thicknesses of the different surfaces have been substituted. By means of a geometric ray tracing, the surgery has been simulated by changing the anterior corneal radius and the corneal thickness within the optical zone to obtain its influence in the ocular image and the visual acuity. We considered the surgery to be <> when the residual equivalent refraction was between 0 and +0.5 D.

An interval for the final corneal radius is proposed for each eye in order to reach the best visual acuity (optimal interval). The position of the post-surgical radius in this interval has been related with the success of the surgical process.

An objective method for LASIK has been proposed: i) it calculates a personalized surgical plan that allows the patient to reach the best visual quality, and ii) it can be used as a reference by the surgeon to design his nomogram and to decrease his learning curve.