J. Schwiegerling et Rw. Snyder, Corneal ablation patterns to correct for spherical aberration in photorefractive keratectomy, J CAT REF S, 26(2), 2000, pp. 214-221
Purpose: To determine the spherical aberration introduced by photorefractiv
e keratectomy (PRK) and customize ablation patterns to compensate for this
aberration and improve post-PRK visual performance.
Setting: Department of Ophthalmology, University of Arizona, Tucson, Arizon
a, USA.
Methods: Presurgical and postsurgical corneal topography of 16 patients who
had PRK with the Summit OmniMed laser were obtained. The data were applied
to a schematic eye model, and exact ray tracing was used to determine the
introduction of spherical aberration from the procedure. Optimization routi
nes were used to determine the ideal ablation pattern.
Results: The magnitude of the spherical aberration introduced into the eyes
after PRK increased with the level of attempted correction. The theoretica
l ideal ablation pattern requires additional flattening of the ablation per
iphery to avoid the introduction of spherical aberration.
Conclusions: Current PRK ablations introduce spherical aberration into the
eye. Modifying the existing ablation algorithms to compensate for spherical
aberration may boost postoperative visual performance. (C) 2000 ASCRS and
ESCRS.