Photorefractive keratectomy for low-to-moderate myopia and astigmatism with a small-beam, tracker-directed excimer laser

Objective: To assess the safety and effectiveness of the Autonomous Technol ogies Corporation LADARVIsion excimer laser system for photorefractive kera tectomy correction of myopia and astigmatism. Design: A multicenter, prospective, noncomparative case series. Participants: The cohort consisted of 467 eyes corrected for spherical myop ia and 211 eyes corrected for myopia with astigmatism. Intervention: Treatments were performed at six sites in the United States u sing a 6-mm ablation zone for spherical myopes and a 5.5-mm zone with a 1.0 -mm blend for astigmats. Main Outcome Measures: Visual acuity, subjective refraction, corneal haze, intraocular pressure, complications, adverse reactions, patient satisfactio n, and corneal endothelial changes. Results: Twelve-month follow-up was available on 414 spherical eyes and 175 astigmatic eyes. The results for spherical eyes with correction between -1 and -5.99 diopters (D) were: uncorrected visual acuity (UCVA) of 20/40 or better achieved by 98.1%, 20/20 or better by 72%, 1.8% lost 2 lines and 0.3 % lost greater than 2 lines of best spectacle-corrected Visual acuity (BSGV A); 76.4% were within 0.50 D of the target correction and 94.4% were within 1.00 D. The results for myopia with astigmatism with spherical equivalent correction between -1 and -5.99 D were: UCVA of 20/40 or better in 97.4%, 2 0/20 or better in 61.7%, 2.5% lost 2 lines and no eyes lost greater than 2 lines BSCVA; 73.9% were within 0.50 D of the target correction and 95% were within 1.00 D. For spherical myopes combined with myopic astigmats correct ed for 6 to 10 D, results were: UCVA of 20/40 or better in 93.4%, 20/20 or better in 61.2%, 2.3% lost 2 lines and no eyes lost greater than 2 lines of BSCVA; 67.2% were within 0.50 D of the desired correction and 87.8% were w ithin 1.00 D. Refractive stability was achieved between 3 and 6 months for the spherical and astigmatic groups. No eyes had corneal haze graded as mod erate or greater, and there was no significant decrease in endothelial cell density. Conclusions: Patients treated for 1 to 10 D of spherical equivalent myopia, with or without astigmatism, showed early refractive stability, excellent UCVA, no significant loss of BSCVA, no loss of endothelial cell density, an d very low levels of corneal haze to 12 months after surgery.