The Effect of LASIK on Best-Corrected High-And Low-Contrast Visual Acuity

Optom Vis Sci. 2004 May;81(5):362-8. doi: 10.1097/01.opx.0000134910.28898.ce.

Abstract

Purpose: To evaluate the effects of laser in situ keratomileusis (LASIK) and LASIK with concurrent astigmatic keratectomy (LASIK/AK) on high- and low-contrast visual acuity.

Methods: The setting was a university refractive surgery practice. Patients were recruited from those undergoing LASIK or LASIK/AK for myopia (>1.00 D spherical equivalent) between May 1996 and August 1997. All subjects were at least 21 years of age. Testing occurred preoperatively and 3 and 6 months after LASIK. Main outcome measures were best spectacle-corrected, high- and low-contrast visual acuity.

Results: For all subjects, there was a significant effect of surgery on nondilated low-contrast visual acuity (repeated measures two-way analysis of variance, p < 0.0001). Tukey's posthoc analysis showed that preoperative low-contrast visual acuity scores were significantly different from 3-month [0.08 logarithm of the minimum angle of resolution (logMAR)] and 6-month (0.11 logMAR) scores for patients undergoing LASIK and LASIK/AK. Under dilated conditions, there was a significant effect of surgery for high- and low-contrast visual acuity (analysis of variance, p < 0.0001 for both). Only changes in low-contrast visual acuity were clinically meaningful [LASIK, visual acuity reduction of 0.1 logMAR (1 line); LASIK/AK, visual acuity reduction of 0.15 logMAR (1.5 lines)]. When considering high and low myopes separately (LASIK only), the level of myopia had a significant effect on the visual acuity after surgery (analysis of variance, p = 0.01). Preoperative, dilated, low-contrast visual acuity scores for high myopes were significantly different from 3-month (0.14 logMAR) and 6-month (0.13 logMAR) scores. No differences were noted for low myopes.

Conclusions: Clinically meaningful postoperative changes in low-contrast visual acuity were noted in patients undergoing LASIK and LASIK/AK under natural and dilated conditions. Postoperative, dilated, low-contrast visual acuity scores were significantly worse than preoperative scores for high myopes, but remained unchanged for low myopes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Astigmatism / physiopathology
  • Astigmatism / surgery*
  • Contrast Sensitivity / physiology
  • Cornea / surgery
  • Humans
  • Keratomileusis, Laser In Situ*
  • Myopia / physiopathology
  • Myopia / surgery*
  • Ocular Physiological Phenomena
  • Prospective Studies
  • Visual Acuity / physiology*