Third-order theory of central and peripheral eye refraction.

This work presents a theoretical framework based on aberration theory for rotationally symmetric optical systems to describe central and peripheral refraction in non-astigmatic eyes and extend the approach to astigmatic eyes. In the non-astigmatic case, refraction is characterized using axial defocus, field curvature, and oblique astigmatism. For astigmatic eyes, the impact of axial astigmatism is analyzed by exploring its interaction with oblique astigmatism. Theoretical predictions are compared with wavefront simulations performed in Zemax, showing consistent values and spatial distributions. In non-astigmatic eyes, refraction retains rotational symmetry with a radially oriented astigmatism axis. In contrast, astigmatic eyes exhibit symmetry breaking: the spherical equivalent decreases along the axis of axial astigmatism and increases in the orthogonal meridian, while astigmatism presents a binodal pattern. This framework aims to provide a solid theoretical basis that complements both experimental data and optical simulations, offering insight into the mechanisms governing central and peripheral refraction.