Elsevier

Ophthalmology

Volume 106, Issue 3, 1 March 1999, Pages 447-457
Ophthalmology

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.
https://doi.org/10.1016/S0161-6420(99)90102-1Get rights and content

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.

Section snippets

Patient population

Thirty-three patients with myopia (66 eyes) were enrolled in the study between October 1993 and March 1994. Each patient received LASIK in one eye (LASIK group) and PRK in the other eye (PRK group) during the same surgical session by the same surgeon using the same laser and microkeratome in the outpatient surgery center of the El-Maghraby Eye Hospital, Jeddah, Saudi Arabia. The order of the two laser procedures and the eye treated were first randomized using a random number table.

Inclusion

Patient population

There were 22 male and 11 female patients ranging in age from 16 to 59 years (mean, standard deviation, 26.2 ± 9.3 years). The baseline spherical equivalent of the manifest refraction ranged from −2.30 to −8.10 D (mean, −4.80 ± 1.60 D in LASIK-treated eyes and −4.70 ± 1.50 D in PRK-treated eyes). Mean baseline refractive cylinder power was 0.50 ± 0.40 D (range, 0–1.75 D) in LASIK-treated eyes and 0.40 ± 0.40 D (range, 0–1.50 D) in PRK-treated eyes. Mean baseline keratometric power was 43.7 ±

Study design

This trial controlled numerous variables by having the same surgeon use the same equipment on two eyes of the same patient during the same surgical session to compare two different procedures: LASIK and PRK. Such a design minimized variability in laser performance, since the laser was calibrated and room conditions were consistent during the approximately 20 minutes required to treat both eyes. The order of the procedures and the order of the eyes for treatment were randomized to decrease any

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