Recovery of corneal subbasal nerve density after PRK and LASIK

Am J Ophthalmol. 2005 Dec;140(6):1059-1064. doi: 10.1016/j.ajo.2005.07.027.

Abstract

Purpose: To measure and compare the return of corneal innervation up to 5 years after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

Design: Prospective, nonrandomized clinical trial.

Methods: Eighteen eyes of 12 patients received PRK to correct a mean refractive error of -3.73 +/- 1.30 diopters, and 16 eyes of 11 patients received LASIK to correct a mean refractive error of -6.56 +/- 2.44 diopters. Corneas were examined by confocal microscopy before and at 1, 2, 3, and 5 years after the procedures. Subbasal nerve fiber bundles were measured to determine density (visible length of nerve/frame area) and expressed as micrometers per square millimeters. Differences were compared by Friedman's test and adjusted for multiple comparisons by the Student-Newman-Keuls procedure.

Results: After PRK, mean subbasal nerve density was reduced by 59% at 1 year (2764 +/- 1321 microm/mm(2) [+/-SD]) when compared with preoperative (6786 +/- 1948 microm/mm(2); P < .001). By 2 years, subbasal nerve density (6242 +/- 1763 microm/mm(2)) was not significantly different from density before PRK and remained unchanged to 5 years (5903 +/- 3086 microm/mm(2)). After LASIK, subbasal nerve density was reduced by 51%, 35%, and 34% at 1, 2, and 3 years, respectively (P < .001). By 5 years, subbasal nerves had returned to densities (4441 +/- 2819 microm/mm(2)) that were not significantly different from densities before LASIK (5589 +/- 2436 microm/mm(2)).

Conclusion: Corneal subbasal nerve density does not recover to near preoperative densities until 5 years after LASIK, as compared with 2 years after PRK.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cornea / innervation*
  • Female
  • Humans
  • Keratomileusis, Laser In Situ / methods*
  • Lasers, Excimer
  • Longitudinal Studies
  • Male
  • Microscopy, Confocal
  • Middle Aged
  • Myopia / surgery*
  • Nerve Fibers / physiology
  • Nerve Regeneration / physiology*
  • Ophthalmic Nerve / physiology*
  • Photorefractive Keratectomy / methods*
  • Prospective Studies