Purpose:: To evaluate clinically a formula based on spherical Gaussian
optics for enhanced predictability of excimer photorefractive keratec
tomy (PRK) in both high and low degrees of myopia. Methods: Patients (
24 eyes) were evaluated preoperatively with refractive measurements an
d corneal topography. After excimer PRK (3-24 months), postoperative r
emaining spectacle correction and corneal topography were measured. Th
e attempted laser correction, calculated using algebraic equations, wa
s compared with the achieved laser correction. Result: The absolute la
ser correction error (mean +/- standard deviation), defined as the dif
ference between the achieved and attempted laser corrections, was 0.37
+/- 0.31 diopter (D) for the 24 eyes. No significant difference was f
ound in the error for attempted corrections greater than 6 D versus th
ose less than 6 D. Conclusions: The use of a spherical Gaussian optics
formulation results in accurate laser correction values for a wide ra
nge of myopia, even for large diopter corrections.