A possible origin of the inverted vertebrate retina revealed by physical modeling

Abstract The evolutionary origin of the inverted retina in the vertebrate eye is unknown. This paper explores a hypothetical evolutionary scenario that explains the illogical orientation of the photoreceptors in the vertebrate retina. The proposed scenario follows the scientific accepted scenario for eye evolution and gradually builds up toward a proto-eye by considering light direction detection and increase in achievable spatial resolution as the driving forces. It suggests that eye retinas developed along two different morphological processes. An evagination process that results in the inverted retina in vertebrate eyes. An invagination process that results in a verted retina in mollusc eyes. The development of the inverted vertebrate retina and proto-eye morphology is strongly substantiated by physics of vision. The proposed evolutionary sequence for vertebrate eye development is simple and has the full potential to explain the origin of the inverted retina and leads to a proto-eye enabling visual detection and orientation. It allows the emergence of eye structures like, extraocular muscles, cornea, lens, and pupil. This study supports the suggestion that a primitive inverted retina in the predecessor of vertebrates is of ectodermal origin and available before neurulation occurred.