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C Ballentine, H Gross, RA Applegate, E Sarver, CA Sarver; Visual Impact as a Function of Zernike Mode and RMS Error . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2032.
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© ARVO (1962-2015); The Authors (2016-present)
Background: Normalized Zernike coefficients reveal the relative contributions of each Zernike mode to the total wavefront error (WFE). It is unknown how visual acuity varies with the magnitude of RMS error in each Zernike mode. Purpose: To determine the relative impact on high and low contrast log MAR acuity of individual Zernike modes (3 through 14) as a function of the magnitude of the RMS error. Methods: 3 healthy volunteers with 20/16 or better acuity served as subjects. CTViewTM (Sarver and Associates, Inc.) was used to generate high resolution simulated retinal images of high and low contrast log MAR charts at different RMS error levels (0.0, 0.05, 0.10, 0.15, 0.20, and 0.25µ over a 6mm pupil ) for Zernike coefficients 3 - 14 projected into object space at 10 ft. RMS converted to equivalent defocus - ranged from 0.00 to 0.19 diopters. Subjects were dilated with 1% cyclopentolate hydrochloride. The foveal achromatic axis of the eye was aligned to a 3 mm pupil using an achromatic alignicator and a bite bar mounted to a 3 dimensional translator, and optimally refracted for the 10' test distance (i.e., eyes are close to if not diffraction limited at a 3 mm pupil diameter). Aberrated acuity charts were read until 5 letters were missed. Data was normalized to the acuity obtained by reading unaberrated charts and plotted as letters lost as function of RMS error. Results: Increasing aberrations, regardless of Z-mode decreased the mean acuity in a linear fashion. Letters lost/0.1 micrometers RMS error (Slope/10) for Zernike modes ordered from least (-0.9) to greatest (-4.0) for high contrast acuity are: Z10, Z6, Z11, Z9, Z14, Z7, Z12, Z3, Z5, Z8, Z13, Z4. For low contrast acuity (least -1.6, greatest -5.2): Z5, Z3, Z9, Z6, Z14, Z10, Z11, Z13, Z7, Z8, Z12, Z4. Conclusion: (1) The decrease in visual performance with increasing RMS error is well described by a linear function. (2) The slopes of the linear functions vary significantly with mode particularly for the high contrast charts. (3) The lower the absolute value of the angular frequency of the Zernike mode the larger the visual impact.
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