Randomized bilateral comparison of excimer laser in situ keratomileusis and photorefractive keratectomy for 2.50 to 8.00 diopters of myopia
Presented in part at the American Academy of Ophthalmology annual meeting, Atlanta, Georgia, October 1995.
Received 25 March 1996; accepted 26 October 1998.
Abstract
Objective
To compare effectiveness, safety, and stability of excimer laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for low-to-moderate myopia.
Design
Prospective, randomized, bilateral study.
Participants
Thirty-three patients with a manifest refraction of −2.50 to −8.00 diopters (D) participated.
Intervention
For each patient, one eye received LASIK and the other received PRK. The first eye treated, and surgical method in the first eye, were randomized. Both eyes were treated by the same surgeon during the same operative session with a Summit Omnimed I laser (6-mm-diameter ablation) and a Chiron Automated Corneal Shaper. Follow-up was 90% at 1 and 2 years.
Results
At baseline, mean (±standard deviation) spherical equivalent manifest refraction was −4.80 ± 1.60 D in LASIK-treated eyes and −4.70 ± 1.50 D in PRK-treated eyes. At 1 day after surgery, 81% of patients (21 eyes) reported no pain in the LASIK-treated eye, whereas no patient (0%) reported being pain-free in the PRK-treated eye. At 3 to 4 days after surgery, 18 (80%) LASIK-treated eyes either improved or remained within 1 line of baseline spectacle-corrected visual acuity; only 10 (45%) PRK-treated eyes achieved this result. At 2 years after surgery, 18 (61%) LASIK- and 10 (36%) PRK-treated eyes achieved an uncorrected visual acuity of 20/20 or better, with no statistically significant difference in refractive outcome between the two techniques. Quantitative videokeratography showed more regularity after LASIK. Complications were similar in the two groups. Patients preferred LASIK by a margin of 2 to 1 at 1 year but showed no preference at 2 years.
Conclusions
Using a 6-mm-diameter single-pass, large area ablation and an automated microkeratome to treat myopia of −2.50 to −8.00 D with 1.00 D or less astigmatism in 1994, the authors used LASIK to produce a higher percentage of eyes with an uncorrected visual acuity of 20/20 or better, more regular postoperative corneal topography, less postoperative pain, and more rapid recovery of baseline spectacle-corrected visual acuity than PRK. Both LASIK and PRK achieved successful correction of low-to-moderate myopia at 1 and 2 years after surgery.
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