The neural retina
Retina
The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which translates that image into electrical neural impulses to the brain to create visual perception, the retina serving a function analogous to that of the film or image sensor in a camera.
What are the three types of neurons in the retina?
neurosensory retina This is composed of all the layers of the retina, except the outer pigmented layer (called retinal pigment epithelium). It comprises three main groups of neurons: (1) the photoreceptors, (2) the bipolar cells, and (3) the ganglion cells.
What is the function of the layers of the retina?
Layers of the Retina. These cells take the electrical information from the photoreceptor cells and pass it along to other retinal cells. Ganglion cells – These cells extend to form an optic nerve that conveys information to the brain and take the electrical information from the bipolar cells and process it to determine shapes, contrast and color.
What is the structure of the retina?
The retina consists of an outer pigmented layer and an inner nervous stratum or retina proper: The pigmented layer consists of a single stratum of cells.
What is retinal pigment epithelium?
Retinal pigment epithelium – This is a single layer of cells that provide essential nutrition and waste removal for the photoreceptor cells.
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What is the retina made of?
The retina is composed of light-sensitive neurons arranged in three layers; the first layer is made up of rods and cones and the other two transmit impulses from the rods and cones to the optic nerve. The rods are sensitive in dim light, and the cones are sensitive in bright light and are responsible for color vision. Disorders of the Retina.
What are the parts of the retina?
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.
What is the term for the separation of the retina from the choroid?
detachment of the retina is complete or partial separation of the retina from the choroid, the middle coat of the eyeball. It occurs most often in persons with myopia (nearsightedness), but it also can result from trauma to the head.
How big is the retina?
The retina proper has an area of about 266 mm2. It lies between the vitreous body and the choroid, and extends from the optic disc to the ora serrata.
Where is the optic papilla located?
About 3.5 mm nasally from the fovea is the optic papilla (optic disk ), where nerve fibers from the retina make their exit and form the optic nerve. This region is devoid of rods and cones and is insensitive to light; hence it is named the blind spot.
Where is the neurosensory layer derived from?
The neurosensory layer is derived embryologically from the inner layer of the optic cup whereas the pigmented layer is derived from the outer layer of the optic cup and they are separated by a potential space which facilitates their separation, as occurs in detached retina. Syn. sensory retina.
Where is the blood-retina barrier?
The blood-retina barrier in the outer third of the retina is formed by the tight junctions of the retinal pigment epithelium cells. See astrocytes; optic cup; optic disc; ectoderm; ocular fundus; fibre layer of Henle; macula; neurotransmitter; neurosensory retina; retinitis; retinopathy; rhodopsin; transduction.