REFRACTIVE-INDEX DISTRIBUTION AND SPHERICAL-ABERRATION IN THE CRYSTALLINE LENS OF THE AFRICAN CICHLID FISH HAPLOCHROMIS-BURTONI

Refractive index distribution in the teleost crystalline lens was meas ured with a nondestructive method in freshly excised lenses of the Afr ican teleost fish Haplochromis burtoni. Independently, spherical aberr ation was measured in a parallel set of lenses. The measured refractiv e index profiles show a continual decrease of refractive index from th e center to the surface of the lens. The H. burtoni lens is of high op tical quality and slightly overcorrected for spherical aberration. Det ails of the small residual spherical aberration were accurately predic ted by ray-tracing model calculations based on the measured refractive index profile. The refractive index profile and the spherical aberrat ion both show more complex characteristics than suggested by earlier m easurements and lens models.