Analysis of the optical properties of crystalline lenses by point-diffraction interferometry.

PURPOSE: To show the feasibility of modified point-diffraction interferometry for the qualitative analysis and accurate quantification of phase aberrations of eye lenses in vitro.
METHOD: Optical aberrations of crystalline lenses in vitro were evaluated by means of a point-diffraction interferometer modified to increase its dynamic range.
RESULTS: Analysis of the Zernike polynomials, Z(m)(n), which contribute significantly to the wavefront aberration of two representative crystalline lenses (a mammalian and a fish lens) is presented. In the mammalian case, the in vitro experiments were performed for pig lenses. It is shown that spherical aberration, astigmatism, coma, and trefoil of different radial orders, n, are the only modes contributing significantly to wavefront aberration, i.e., aberrations with azimuthal frequencies, m, greater that three can be regarded as noise. In the case of fish lenses (sea bream), we show that the technique allows quantification of the deviation from the spherical symmetry which is commonly assumed for teleost fish lenses.
CONCLUSIONS: Modified point-diffraction interferometry is a wavefront-sensing technique that can be used to accurately analyze phase aberrations in eye lenses and hence evaluate their contribution, in terms of significant aberrations, to the total aberrations of the eye.