Wavefront-guided LASIK for myopia: effect on visual acuity, contrast sensitivity, and higher order aberrations.

Abstract

PURPOSE:

To determine the impact of wavefront-guided LASIK for myopia with or without astigmatism on high and low contrast best spectacle-corrected visual acuity (BSCVA), photopic and mesopic contrast sensitivity, and higher order aberrations.

METHODS:

Bilateral wavefront-guided LASIK (LADAR-Vision4000; Hansatome microkeratome) was performed on 324 eyes (162 patients) with a mean spherical manifest refraction of -2.84 +/- 1.35 diopters (D) (range: -0.25 to -6.50 D) and astigmatism of -0.81 +/- 0.74 D (range: 0 to -4.00 D). Mean age was 37.7 +/- 9.3 years (range: 20 to 60 years). Best spectacle-corrected visual acuity and contrast sensitivity were assessed using ETDRS charts and vertical sinusoidal gratings, respectively. Higher order aberrations were measured using a Shack-Hartmann wavefront sensor, analyzed across a 5-mm pupil. Repeated measures and post hoc analyses determined statistical significance (P < .0025). Only right eyes were analyzed.

RESULTS:

One hundred thirty-six eyes (84%) had uncorrected visual acuity of 20/20 or better 6 months postoperative; 80.9% (131 eyes) were within +/- 0.50 D of attempted correction. Statistically significant postoperative improvements were noted in high and low contrast BSCVA (both P < or = .001); in photopic contrast sensitivity at 3, 6, and 12 cycles per degree (cpd); and in mesopic contrast sensitivity at 12 and 18 cpd (all P < .001). With respect to higher order aberrations, a statistically significant change was seen in Zernike coefficients Z3(-1), Z3(1), Z3(-3), Z3(3), and Z4(4) following surgery (range of mean absolute change: 0.042 to 0.142 microm; all P < or = .001). All increased in magnitude except for Z3(-3), which decreased.

CONCLUSIONS:

Despite an increase in higher order aberrations, wavefront-guided LASIK yields excellent visual acuity and contrast sensitivity. Spherical aberration, which increases the most following non-wavefront-guided LASIK, showed no significant change.

• Authors: Nancy J Keir, Trefford Simpson, Lyndon W Jones, Desmond Fonn
• Journal: Journal of refractive surgery (Thorofare, N.J. : 1995) (J Refract Surg) Vol. 25 Issue 6 Pg. 524-33 (06 2009) ISSN: 1081-597X [Print] United States
• PMID: 19603620 (Publication Type: Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adult
• Astigmatism (surgery)
• Contrast Sensitivity (physiology)
• Corneal Topography
• Female
• Humans
• Keratomileusis, Laser In Situ (methods)
• Lasers, Excimer (therapeutic use)
• Male
• Middle Aged
• Myopia (physiopathology, surgery)
• Prospective Studies
• Visual Acuity (physiology)
• Young Adult