Correction factor for ablation algorithms used in corneal refractive surgery with gaussian-profile beams

Abstract

Abstract:We provide a correction factor to be added in ablation algorithms when a Gaussian beam is used in photorefractive laser surgery. This factor, which quantifies the effect of pulse overlapping, depends on beam radius and spot size. We also deduce the expected post-surgical corneal radius and asphericity when considering this factor. Data on 141 eyes operated on LASIK (laser in situ keratomileusis) with a Gaussian profile show that the discrepancy between experimental and expected data on corneal power is significantly lower when using the correction factor. For an effective improvement of post-surgical visual quality, this factor should be applied in ablation algorithms that do not consider the effects of pulse overlapping with a Gaussian beam.

Ablation Resolution in Laser Corneal Refractive Surgery: The Dual Fluence Concept of the AMARIS Platform

“…The system delivers aspheric wavefront-customised profiles and including some optimisations: The aspheric profiles go beyond the Munnerlyn proposed profiles, and add some aspheric characteristics to balance the induction of spherical aberration (prolateness optimisation). These particular case of aspheric profiles compensate for the aberrations induction observed with other types of profile definitions [19], some of those sources of aberrations are those ones related to the loss of efficiency of the laser ablation for nonnormal incidence [20][21][22].…”

Aspheric Refractive Correction of Irregular Astimatism

“…Special ablation patterns were designed to preserve the preoperative level of high-order aberrations 17 , 18 , 19 , if the best corrected visual acuity, in this patient, has been unaffected by the pre-existing aberrations 20 . Thus to compensate for the aberrations induction observed with other types of profile definitions 21 , some of those sources of aberrations are those ones related to the loss of efficiency of the laser ablation for non-normal incidence 22,23,24 . Methods for determining functional optical zones have been used previously.…”

A study of angular dependence in the ablation rate of polymers by nanosecond pulses

“…In recent years it has also been included in fluence calculations for photorefractive laser surgery [15]. The basic assumption of the model seems reasonable if the ablation process is photothermal, as is generally accepted to be the case for ablation of organic materials by nanosecond pulses.…”