Peripheral aberrations in the human eye for different wavelengths: off-axis chromatic aberration

The interest in the eye’s off-axis aberrations has increased strongly. On-axis the conversion of the aberration magnitude between different wavelengths is well known. We verified if this compensation is correct also for off-axis measurements by building a wavelength tunable peripheral Hartmann–Shack sensor and measuring 11 subjects out to +-30° in the horizontal visual field. At the fovea, an average longitudinal chromatic aberration of 1 D between red (671 nm) and blue (473 nm) light was found, and it increased slightly with eccentricity (up to 1:2 D). A similar trend was measured for astigmatism as a function of wavelength (increase ∼0:15 D). Computational ray tracing in model eyes showed that the origin of the small increase of chromatic aberrations with eccentricity is the change of the oblique power of the refractive surfaces in the eye. Factors related to increase of axial length and refractive index of the eye were found to have a very small influence.