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Recovery of Uncorrected Visual Acuity After Laser In Situ Keratomileusis or Photorefractive Keratectomy for Low Myopia

Walker, Mark B. M.D.; Wilson, Steven E. M.D.

Clinical Sciences

Purpose. To compare uncorrected visual acuity and refractive error in patients undergoing photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) between 1 week and 6 months after surgery.

Methods. All eyes underwent PRK or LASIK with the VisX StarS2 excimer laser. We retrospectively analyzed data from 77 random eyes of 77 patients in the PRK group and 76 eyes of 76 patients in the LASIK group. All eyes had a low myopic refractive error (spherical equivalent range, −0.88 diopters (D) to −5.13 D; mean PRK, −2.8 ± 0.20 D; LASIK, −2.5 ± 0.22 D). Uncorrected visual acuity and manifest refractive error were evaluated 1 week, 1 month, and 6 months after surgery.

Results. Each eye undergoing PRK was paired with an eye undergoing LASIK for a similar level of spherical equivalent. Mean uncorrected visual acuity after 1 week was 0.85 ± 0.06 (20/25, logMAR 0.12 ± 0.04) for the PRK group and 1.01 ± 0.06 (20/20, logMAR 0.01 ± 0.03) for the LASIK group (p < 0.001). Mean spherical equivalent after 1 week was 0.23 ± 0.12 D for the PRK group and −0.02 ± 0.07 D for the LASIK group (p = 0.02). Mean uncorrected visual acuity after 1 month was 1.03 ± 0.05 (20/20, logMAR 0.02 ± 0.03) for the PRK group and 1.05 ± 0.05 (20/20, −0.02 ± 0.03) for the LASIK group (p = 0.16). Mean spherical equivalent after 1 month was 0.19 ± 0.10 D for the PRK group and −0.02 ± 0.09 D for the LASIK group. This difference was statistically significant (p = 0.02), but was unlikely to be clinically significant. Mean uncorrected visual acuity after 6 months was 1.05 ± 0.06 (20/20, logMAR −0.01 ± 0.03) for the PRK group and 1.06 ± 0.05 (20/20, logMAR −0.14 ± 0.03) for the LASIK group (p = 0.41). Mean spherical equivalent after 6 months was 0.02 ± 0.08 D for the PRK group and 0.00 ± 0.08 D for the LASIK group (p = 0.35).

Conclusion. Uncorrected visual acuity 1 week after surgery is significantly better in eyes undergoing LASIK than in eyes undergoing PRK. Both procedures provide functional vision by 1 week after surgery. The difference does not relate to refractive error, which was similar between the two groups, but to differences in healing of the epithelium. By 1 month after surgery, there is no difference in mean uncorrected visual acuity between eyes that undergo PRK or LASIK for low myopia.

From the Department of Ophthalmology, The University of Washington School of Medicine, Seattle, Washington, U.S.A.

Submitted April 4, 2000.

Revision received September 26, 2000.

Accepted October 3, 2000.

Address correspondence and reprint requests to Dr. Steven E. Wilson, Department of Ophthalmology, Box 356485, University of Washington, Seattle, WA 98195–6485, U.S.A.

Supported in part by grant EY10056 from the National Eye Institute in Bethesda, Maryland, the University of Washington, and an unrestricted grant from Research to Prevent Blindness in New York, New York.

The authors have no commercial or proprietary interests in any of the products discussed in this manuscript.

© 2001 Lippincott Williams & Wilkins, Inc.