Comparison of wavefront-guided and wavefront-optimized refractive surgeries for astigmatism of 0.75 diopters or less

Abstract

Purpose : To compare the refractive outcomes of wavefront-guided (WFG) and wavefront-optimized (WFO) refractive surgeries in myopic eyes with low refractive cylinder.

Methods : The study comprised of subjects electing to undergo either photorefractive keratectomy (PRK) or laser-assisted in situ keratomileusis (LASIK) for myopic astigmatism. Each subject was randomly assigned to either WFG or WFO treatment. WFG surgeries were performed using the VISX CustomVue STAR S4 IR (Abbott Medical Optics) whereas WFO surgeries were done using Wavelight Allegretto Wave EyeQ (Alcon Surgical). The refractive target was emmetropia in all eyes. Data analysis included eyes with preoperative refractive cylinder of 0.75 diopters (D) or less. Refractive outcomes including astigmatic changes were assessed and compared between WFG and WFO groups.

Results : Data from 230 eyes (105 WFG and 125 WFO eyes) of 150 subjects (mean age 30.5 years ±6.4) with preoperative cylinder 0.75 D or less were analyzed. The mean preoperative refractive sphere was –3.39 D ±1.60 for WFG and -3.20 D ±1.52 for WFO group (p=0.36); the cylinder was -0.50 D ±0.19 for WFG and -0.50 D ±0.20 for WFO group (p=0.93). At 6 months postoperatively, 99.0% of WFG eyes vs. 98.3% WFO eyes achieved uncorrected distance visual acuity (UDVA) of 20/20 or better (p=0.99); 77.8% of WFG vs. 76.7% of WFO eyes had UDVA of 20/15 or better (p=0.87); 94.9% of WFG eyes vs. 98.3% of WFO eyes had refractive spherical equivalent within ±0.50 D of emmetropia (p=0.25); and 93.9% of WFG vs. 90.8% of WFO eyes had (non-vector) refractive cylinder ≤0.50 D (p=0.45). The mean magnitude of error was 0.01 D ±0.20 for WFG and 0.13 D ±0.25 for WFO group (p<0.001). The applied treatment was within 15 degrees of the intended treatment axis in 70.7% of WFG eyes and 74.2% of WFO eyes (p=0.65). The correction index (surgically induced astigmatism/target induced astigmatism) was 1.06 for WFG and 1.39 for WFO treatment (p<0.001).

Conclusions : In myopic eyes with ≤0.75 D of astigmatism, WFO-treated eyes tended to be overcorrected compared to WFG-treated eyes. This notwithstanding, both laser platforms were effective and comparable in achieving excellent visual acuities postoperatively.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.