Refractive index distribution in the porcine eye lens for 532 nm and 633 nm light

Aims To measure the refractive index distribution in porcine eye lenses for two wavelengths from the visible spectrum: 532 and 633 nm, in order to determine whether there are any discernible wavelength dependent differences in the shape of the profile and in the magnitude of refractive index. Methods Rays were traced through 17 porcine lenses of the same age group and of similar size. Ray trace parameters were used to calculate the refractive index distributions for 633 nm light in all 17 lenses and for 532 nm light in 10 lenses. The effect of the refractive index at the edge of the lens, on the rest of the profile, was considered because the mismatch between refractive index at the lens edge and the refractive index of the surrounding gel necessitated a further step in calculations. Results The shape of the refractive index distributions is parabolic. There is a small wavelength dependent difference in the magnitude of the refractive index across the profile and this increases very slightly into the centre of the lens. The value of the refractive index at the edge of the lens does not appreciably affect the index profile. Conclusions The wavelength dependent differences in refractive index between light of 633 and 532 nm are small but discernible.