Wavefront-guided LASIK for Myopia: Effect on Visual Acuity, Contrast Sensitivity, and Higher Order Aberrations

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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 (LADARVision4000; 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≤.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 Symbol, Symbol, Symbol, Symbol, and Symbol following surgery (range of mean absolute change: 0.042 to 0.142 μm; all P≤.001). All increased in magnitude except for Symbol, 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.

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