Optical quality and anisotropy across the retina of Chinese children's eyes.

The goal of this study was to characterize the retinal image quality across the retina, in individual children, as a function of wavelength. The wavefront aberrations of 30 Chinese children (ages 12.8±1.8yrs) were measured with a custom-developed Shack-Hartmann wavefront sensor and analyzed at the fovea, 10 deg, 20 deg, and 30 deg in the nasal visual field (VF), -30deg temporal VF, and ±16deg in the vertical VF. Wavefront aberrations (e.g., oblique astigmatism) increased in the peripheral retina, and consequently, computed image quality degraded and exhibited a significant directionality. We quantified point spread function (PSF) orientation with optical anisotropy (OA), the ratio of radial by anti-radial (i.e., perpendicular to radial) volumetric modulation transfer functions. We found that the eccentricity-driven increase in OA was wavelength dependent: peripheral PSFs in the blue (405 nm) wavelength became more radial, whereas green (555 nm) and red (695 nm) wavelengths became more anti-radial as a function of eccentricity. Also, the peripheral PSF was more anti-radially oriented in myopes than in emmetropes. Further work is needed to uncover retinal mechanisms which may employ these chromatic and anisotropic cues for the sign of defocus.