pars optica retinae


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ret·i·na

(ret'i-nă), [TA]
Grossly, the retina consists of three parts: optic, ciliary, and iridial. The optic part, the physiologic portion that receives the visual light rays, is further divided into two parts, the pigmented part (pigment epithelium) and the nervous part, which are arranged in the following ten layers: pigmented layer; layer of inner and outer segments (of rods and cones); outer limiting layer (actually a row of junctional complexes); outer nuclear layer; outer plexiform layer; inner nuclear layer; inner plexiform layer; ganglionic (cell) layer; layer of nerve fibers; and inner limiting layer. Layers 2-10 comprise the neural layer. At the posterior pole of the visual axis is the macula, in the center of which is the fovea, the area of acute vision. Here, layers 6-9 and blood vessels are absent, and only elongated cones are present. About 3 mm medial to the fovea is the optic disc, where axons of the ganglionic cells converge to form the optic nerve. The ciliary and iridial parts of the retina are forward prolongations of the pigmented layer and a layer of supporting columnar or epithelial cells over the ciliary body and the posterior surface of the iris, respectively.
Synonym(s): optomeninx
[Mediev. L. prob. fr. L. rete, a net]

ce·re·bral lay·er of ret·i·na

the internal layer of the retina containing the neural elements, as distinguished from the outer leaf of the retina, or pigmented layer.

pars optica retinae

The sensory portion of the retina, extending from the optic disk to the ora serrata.
See also: pars
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