Читать книгу Essentials of Veterinary Ophthalmology - Kirk N. Gelatt - Страница 80

The choroid, ciliary body, and iris are supplied primarily by the uveal vessels. The outer retina in some animals (e.g., dogs, cats, ruminants, and pigs) and almost all or the entire retina in others (e.g., horses and guinea pigs) is nourished by diffusion from the choroidal vessels. The inner retina is supplied by retinal vessels in many species. Blood vessels supplying the cornea and lens in the embryo regress before birth or shortly thereafter, leaving the AH as the primary source of nutrients for the cornea and lens.

Birds have a unique structure, the pecten oculi, which is a heavily pigmented, highly vascularized, and usually fanlike structure projecting from the surface of the optic nerve into the vitreous. A similar structure occurs in reptiles, termed the conus papillaris. The avian pecten likely functions as an important source of nutrients for the inner retina. This assumption is based on the observations that the avian retina is thicker than oxygen could perfuse from the choroid and that the pectinate artery resistive and pulsatility indices are low. Several marine mammals, the bottlenose dolphin (Tursiops truncatus), spotted seal (Phoca largha), and California sea lion (Zalophus californianus), have an ophthalmic rete from which the retinal and choroidal arteries are derived.