A quantitative description of lens eye morphology and its implications.

If it is assumed that the differences between eyes constitute adaptations to different visual environments, then it should be possible to identify the visual environments for which the eye is optimised from these differences. Two different classes of simple eye shapes can be distinguished from the ratio of maximum pupil size to the axial length of an eye. The quantitative description of the two different eye shapes can be used to identify the relative importance of image illumination and resolution to an animal from a cross-section of its eye.