Purchase this article with an account.
Denise S. Ryan, Lamarr Peppers, Rose K. Sia, Michael J. Mines, David Cute, Richard D. Stutzman, Robin S. Howard, Kraig S. Bower; Comparison of Contrast Threshold after Wavefront-guided vs. Wavefront-optimized Photorefractive keratectomy (PRK). Invest. Ophthalmol. Vis. Sci. 2012;53(14):1474.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To compare the contrast threshold (CT) of Wavefront-guided (WFG) vs. Wavefront-optimized (WFO) PRK.
Participants randomized to receive WFG PRK (VISX Star S4, Abbot Medical Optics) or WFO PRK (Wavelight Allegretto Wave Eye-Q, Alcon Surgical) underwent binocular testing to determine their CT preoperatively with correction and at 1,3, and 6 months postoperatively without correction. Participants responded to stimuli presented by the Metropsis Visual Stimulus Generation Device (ViSaGe, Cambridge Research Systems Ltd.) at five different spatial frequencies (SF): 1.5, 3.0, 6.1, 13.1, and 19.7 cycles per degree (cpd). Metropsis software calculated the average CT for each spatial frequency. A Wilcoxon signed rank test was used to compare preoperative and 6 month WFG and WFO CT values. A repeated measures analysis of variance (RM-ANOVA) was used to compare WFG vs. WFO PRK at each spatial frequency over time. A p-value <0.05 was considered significant.
PRK was performed on 28 WFG and 26 WFO participants. There were no significant differences in preoperative age or manifest spherical equivalent (MSE): Age: 30.3 ±7.1 years (y) WFG vs. 29.9 ±5.6y, p=0.75(WFO); MSE: -3.53±1.95 Diopters (D) WFG vs. -3.32±1.79 WFO, p=0.57. Binocular results of the CT at each spatial frequency are presented in Table 1.
Results show there is no significant difference in binocular contrast threshold when comparing WFG to WFO PRK. CT is not diminished after either WFG or WFO PRK. For patients who underwent WFO PRK, at SF 3.0 and 13.1, there was noted improvement. Ongoing testing in this study will determine if WFG or WFO generated optical quality affects task performance.
This PDF is available to Subscribers Only