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Gaussian optics for photorefractive keratectomy. Increased predictability for larger diopter corrections
1Department of Ophthalmology, Institut Arthur Vernes, Paris, France.
Purpose:
To evaluate clinically a formula based on spherical Gaussian optics for enhanced predictability of excimer photorefractive keratectomy (PRK) in both high and low degrees of myopia.
Method:
Patients (24 eyes) were evaluated preoperatively with refractive measurements and corneal topography. After excimer PRK (3-24 months), postoperative remaining spectacle correction and corneal topography were measured. The attempted laser correction, calculated using algebraic equations, was compared with the achieved laser correction.
Results:
The absolute laser correction error (mean +/- standard deviation), defined as the difference between the achieved and attempted laser corrections, was 0.37 +/- 0.31 diopter (D) for the 24 eyes. No significant difference was found in the error for attempted corrections greater than 6 D versus those less than 6 D.
Conclusion:
The use of a spherical Gaussian optics formulation results in accurate laser correction values for a wide range of myopia, even for large diopter corrections.