ABSTRACT
ANATOMY AND PHYSIOLOGY The uvea is the vascular tunic of the eye and the anterior uvea consists of the iris and ciliary body (11.1, 11.2). The most striking species differences in the anterior uvea is in pupil shape and reactivity to light. The PLRs of ungulates are more sluggish than those of carnivores. Topographically, the iris is divided grossly into a thick
peripheral ciliary zone and a thinner central pupillary zone, with the collarette forming the junctional area (11.3). Remnants of the embryonic pupillary membrane may occasionally be observed arising from the collarette region. The pupillary border has a ‘ruff’ of pigment formed by the central extension of the posterior pigmented epithelial layers. In ungulates, this pigment extension is exaggerated dorsally and ventrally to form the granula iridica or
11.1 Illustration of the canine globe with the three tunics of the eye.
