Optimum corneal asphericity of myopic eyes for refractive surgery

In this work, an improvement to the Munnerlyn formula used in refractive surgery is proposed by selecting the final corneal asphericity. A theoretical optical analysis has been performed by adopting the RMS (root mean square) spot size as a merit function. Two different sets of myopes having refractive errors ranging up to -7D have been tested. The results show that a corneal asphericity of around Q = -0.61, with the radius provided by the emmetropization formula based on thin lens theory, may improve image quality after surgery. This value could be used in practical surgery because it is easy to implement in the ablation algorithm and it requires no additional data from other clinical surgery instrumentation.