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LASIK yielded better long-term refractive stability than PRK
J Cataract Refract Surg. 2010;36(10):1709-1717.
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Laser refractive surgery proved effective for all degrees of myopia and offered long-term refractive stability, a study found.
"Refractive stability was achieved within 1 year postoperatively, with LASIK showing better stability than PRK for up to 6 to 9 years," the study authors said.
The comparative case series included 389 eyes of 229 patients; specifically, 247 eyes had low to moderate myopia and 142 eyes had high myopia. In the low to moderate myopia group, 85 patients underwent PRK and 162 patients underwent LASIK. In the high myopia group, 40 patients underwent PRK and 102 patients underwent LASIK.
The mean postoperative follow-up interval was 4.91 years (range: 2 to 13 years).
Study results showed that the low to moderate myopia group attained better uncorrected distance visual acuity than the high myopia group. In addition, the LASIK group had better postoperative uncorrected distance visual acuity than the PRK group.
In the PRK group, 45.9% of eyes with low to moderate myopia and 25% of eyes with high myopia were within 0.5 D of targeted refraction by the end of the study. In the LASIK group, 64.8% of eyes with low to moderate myopia and 37.3% of eyes with high myopia were within 0.5 D of the refractive goal by the end of the study.
In many ways, this study confirms what we already know. We know how the degree of preoperative myopia correlates with postoperative best uncorrected visual acuity. We also know rates of myopic regression and under/overcorrection for both PRK and LASIK. This study reinforces this in a large cohort of patients. However, this study is not without flaws. First of all, modern-day LASIK surgeons around the world are adopting femtosecond laser flap creation, while this study utilizes older-style microkeratomes. This study utilizes 13 different surgeons using evolving laser technology and techniques over a 13-year period, which is not ideal. In addition, follow-up declined precipitously over time, which makes it impossible to draw conclusions about outcomes. Patients tend not to follow up either because they are doing well or because they had a complication and went somewhere else for care. Both scenarios could have a dramatic effect on the outcomes purported by this study. Even in the face of these limitations, however, LASIK does show more stability than PRK, and this should be an ongoing focus of investigation.
– Ronald R. Krueger, MD, MSE
Professor of
Ophthalmology, Medical Director of Refractive Surgery
– Brian Armstrong, MD
Refractive and
cornea fellow, Cleveland Clinic