Models in Ophthalmology and Vision Research

This chapter reviews the anatomy and physiology of the rabbit eye from a comparative perspective. The anatomy of the rabbit eye reflects its niche as a diurnal herbivore. The rabbit has both photopic and scotopic vision without the benefit of a tapetum. Orbits are laterally situated; the rabbit is one of the few animals in which the orbital axis coincides with the visual axis. The shape of the orbit is circular, compared to the cone shaped human orbit. The orbital walls are of bone, except inferiorly, where the wall is formed partially by the muscles of mastication. The superior orbital wall is formed by the frontal bone. The supraorbital process of the frontal bone contains three supraorbital foramina, which are unique feature of the rabbit orbit; the foramina are incisures formed into apertures by a cartilaginous sheet. The optic foramina share a common canal anteriorly with only a thin boney plate to divide them, which disappears posteriorly to form one canal opening into the cranium as a single foramen. Entropion in young rabbits can occur as a primary or as a secondary condition arising from infection. Viral-induced eyelid proliferations can result from infection by the rabbit myxoma and papilloma viruses. The papilloma virus is a part of the papovaviridae and is a DNA virus transmitted by arthropod vectors. The cottontail rabbit in the mid-western United States is most frequently affected, although domestic rabbits are susceptible.