The retina of the eye is a light-absorbing layer that covers about 65% of the inner surface of the back of the eye. Two types of photosensitive cells, rods and cones, in the retina convert light into signals that are transmitted to the brain by means of the optic nerve. In the center of the retina one can find the central pit (fovea) (fovea or fovea centralis). The fovea constitutes the center of the area of the eye with the sharpest vision, the macula. Most color perception is also carried out in the area of the fovea.
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The neurosensory retina
April 2, 2017Macula lutea ("the yellow spot") – the posterior part of the retina that contains pigment due to xanthophyll. Histologically the macula is defined as an area with a diameter of 5-6 mm with 2 or more layers of
To the full articleThe retina of the eye is built of several layers. Here they are from the outside, that is adjacent to the choroid, inward, that is adjacent to the vitreous.
The layers of the retina (10 in total)
1. Retinal Pigment Epithelium – RPE
This is a single-cell layer that begins from the area of the optic disc and continues up to
the Ora Serrata, where it meets the pigmented epithelium of the ciliary body. This layer has several roles:
a. Metabolism of vitamin A
b. Maintaining the outer blood-retina barrier
c. Absorption of light
d. And more…
When the RPE is separated from the photoreceptor layer this is called "retinal detachment". This is an emergency for an ophthalmologist.
2. Photoreceptor layer
The photoreceptor layer is composed of special neuroepithelial cells called rods and cones. The rods are responsible for night vision. In each of the eyes of an average person there are about 120,000,000 rod cells. These cells are located mainly in the periphery of the retina. The cones are responsible for daytime vision and color perception. In each of the eyes of an average person there are about 6,000,000 cones. These cells are located mainly in the area of the fovea.
3. External Limiting Membrane
The external limiting membrane is not really a true membrane and it is composed of the junction points of adjacent photoreceptor cells and Muller cells. Muller cells are in fact glial cells that begin from the external limiting membrane and end at the internal limiting membrane. They provide support to the retina both structurally and nutritionally.
4. Outer Nuclear Layer
In the outer nuclear layer one finds the cell bodies of the rods and cones.
5. Outer Plexiform Layer
The outer plexiform layer is composed of the connections between the photosensitive cells and the horizontal cells, bipolar cells.
6. Inner Nuclear Layer
The inner nuclear layer contains the nuclei of the bipolar cells, horizontal cells, Muller cells or amacrine cells.
7. Inner Plexiform Layer
The inner plexiform layer is composed of connections between the bipolar and amacrine cells and the ganglion cells.
8. Ganglion Cell Layer
The ganglion cell layer is composed of the cell bodies of ganglion cells.
9. Nerve Fiber Layer
The nerve fiber layer is composed of the axons of the ganglion cells. These axons remain non-myelinated until they pass through the Lamina Cribrosa of the optic nerve.
10. Inner Limiting Membrane
Similar to the external limiting membrane, the internal limiting membrane is not a true membrane. It is built from the ends of the Muller cells and connections to the basal lamina.
Retina additional articles:
Vitreous | Retinal vein occlusion | Introduction to the retina | Retinopathy of prematurity |
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