Photorefractive Keratectomy for Myopia Using a 4.5-Millimeter Ablation Zone
George O. Waring, Maureen A. O'Connell, Robert K. Maloney, Kerry B. Hagen, Stephen F. Brint, Daniel S. Durrie, Michael Gordon, Roger F. SteinertBackground:
Argon fluoride (193 nm) excimer laser photorefractive keratectomy for myopia is under evaluation by the United States Food and Drug Administration.
Methods:
We report a consecutive prospective series of 100 patients (one eye per patient) treated as part of the Phase IIB FDA-approved protocol, with 80 patients followed for 1 year. Patients' ages ranged from 21 to 62 years (mean, 35 years). The Summit Technology, Inc ExciMed ® UV200LA with a 4.5-mm diameter ablation was used.
Results:
Baseline spherical equivalent refraction ranged from −2.00 to −6.90 diopters (D) (mean −4.60 D). Ninety-five percent of eyes reepithelialized by 72 hours. At 1 year, the difference between attempted and achieved correction was ± 0.50 D for 42 eyes (53%) and ± 1.00 D for 60 eyes (75%). During the first 6 months, there was a trend toward over-correction and the majority of eyes showed some loss of initial refractive correction; 10 eyes (14%) changed by 1.00 D or more between 6 and 12 months. An uncorrected visual acuity of 20/25 or better was achieved by 50 eyes (63%) and 20/40 or better by 61 eyes (77%). Of the 10 eyes (12%) that lost two or more Snellen lines of spectacle-corrected or glare visual acuity, two had visual acuity of worse than 20/25. Central subepithelial corneal haze was absent to mild in 77 (96%) eyes at 12 months.
Conclusions:
Excimer laser photorefractive keratectomy as performed in this study was generally effective and safe in reducing simple spherical myopia. Further studies of the effect of a larger diameter ablation zone, smoother transitional corneal contours, and the effect of postoperative topical corticosteroids may lead to further improvements in outcome. [