Purchase this article with an account.
Amanda Kingston, Geunyoung Yoon; Impact of Primary and Secondary Spherical Aberration on Predicted Peripheral Image Quality. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4550.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To determine the impact of sign and magnitude of primary and secondary spherical aberration (SA) on predicted image quality at retinal eccentricities up to 20°.
An Arizona eye model was implemented in commercially available optical design software (Zemax Bellevue, WA). Radii of curvature, index and thicknesses were used from the model while axial length and crystalline lens asphericity were varied to produce an eye with zero defocus and SA. Zernike SA up to ±1.00μm over a 6mm diameter was added to the anterior cornea to induce different signs and magnitudes of primary and secondary SA. Foveal retinal image quality with each SA condition was optimized at distance by adjusting defocus. Wavefronts were calculated for an elliptical pupil with a 6mm long axis, at each retinal eccentricity, using Zemax. Through-focus peripheral image quality, using an image-convolution based image quality metric was done with a custom Matlab program. Measured outcomes were retinal image quality, refractive error and depth of focus (DOF) as a function of retinal eccentricity.
For all eccentricities, negative primary SA induced hyperopic defocus whereas positive primary SA and zero SA induced myopic defocus. Peak image quality with zero SA was higher than all eyes with SA, and maintained the same magnitude of myopic shift as primary SA (0.25D and 1.50D at 10 and 20°, respectively). DOF was extended with increasing magnitude of primary SA for all eccentricities compared to the zero SA case. Positive secondary SA induced hyperopic defocus at all eccentricities, whereas negative secondary SA induced myopic defocus. Secondary SA gives a secondary peak image quality instead of single focus found with primary SA. This secondary peak is in the hyperopic direction for positive SA and myopic direction for negative SA. Increasing the magnitude of secondary SA degraded image quality by 26-35% for all eccentricities. Decreasing the magnitude of secondary SA to -0.10μm increased image quality while still maintaining myopic defocus.
Positive primary and negative secondary SA yield acceptable foveal image quality while maintaining myopic defocus at all eccentricities. Inducing optimal primary and secondary SA of the eye with an advanced ophthalmic lens manipulates the amount of refractive defocus and depth of focus in the peripheral retina, potentially providing the ability to control myopia progression.
This PDF is available to Subscribers Only