Are All Aberrations Equal?
- 1 September 2002
- journal article
- Published by SLACK, Inc. in Journal of Refractive Surgery
- Vol. 18 (5)
- https://doi.org/10.3928/1081-597x-20020901-12
Abstract
PURPOSE: To determine for a fixed RMS error (25 µm, over a 6-mm pupil) how each mode of the normalized Zernike polynomial (second through the fourth radial order) affects high and low contrast logMAR visual acuity. METHODS: Three healthy volunteers served as subjects. CTView was used to generate optically aberrated logMAR charts. Accommodation was paralyzed and pupils dilated. The foveal achromatic axis of the eye was aligned to a 3-mm pupil and the eye was optimally refracted. Aberrated acuity charts were read until five letters were missed. Data were normalized for each subject to the acuity obtained by reading unaberrated charts and plotted as letters lost as a function of Zernike mode. RESULTS: Defocus (Z p 0 2 ) decreased letter acuity more than astigmatism (Z p 2 2 , Z^sup -2^ 2 ). Coma (Z p 1 3 , Z^sup -1^ 3 ) decreased acuity more than trefoil (Z p 3 3 , Z^sup -3^ 3 ). Spherical aberration (Z p 0 4 ) and secondary astigmatism (Z p 2 42 , Z^sup -2^ 4 ) decreased acuity much more than quadrafoil (Z p 4 4 , Z^sup -4^ 4 ). CONCLUSIONS: 1. For an equal amount of RMS error not all coefficients of the Zernike polynomial induce equivalent losses in high and low contrast logMAR acuity. 2. Wavefront error concentrated near the center of the pyramid adversely affects visual acuity more than modes near the edge of the pyramid. 3. Large changes in chart appearance are not reflected in equally large decreases in visual performance (ie, subjects could correctly identify highly aberrated letters). 4. Interactions between modes complicate weighting each Zernike mode for visual impact. [J Refract Surg 2002;18:S556-S562]Keywords
This publication has 5 references indexed in Scilit:
- Schematic Eye Models for Simulation of Patient Visual PerformanceJournal of Refractive Surgery, 2001
- Standards for Reporting the Optical Aberrations of EyesPublished by Optica Publishing Group ,2000
- Statistical distribution of foveal transverse chromatic aberration, pupil centration, and angle ψ in a population of young adult eyesJournal of the Optical Society of America A, 1995
- Theory and measurement of ocular chromatic aberrationVision Research, 1990
- The optical transverse chromatic aberration on the fovea of the human eyeVision Research, 1990