What is retina

It is located near the optic nerve. The purpose of the retina is to receive light that the lens has focused, convert the light into neural signals, and send these signals on to the brain for visual recognition. The retina processes light through a layer of photoreceptor cells. These are essentially light-sensitive cells, responsible for detecting qualities such as color and light-intensity.

The retina processes the information gathered by the photoreceptor cells and sends this information to the brain via the optic nerve. Basically, the retina processes a picture from the focused light, and the brain is left to decide what the picture is.

Conditions such as retinal detachment , where the retina is abnormally detached from its usual position, can prevent the retina from receiving or processing light. This prevents the brain from receiving this information, thus leading to blindness. The central retinal artery is a blood vessel inside the eye.

In: Records RE, editor. Physiology of the human eye and visual system. Kolb H. The neural organization of the human retina. Principles and practices of clinical electrophysiology of vision. Louis: Mosby Year Book Inc. Rodieck RW. The vertebrate retina: principles of structure and function.

San Francisco: W. Freeman and Company; The macular pigment. Spatial distribution in primate retina. Neural-vascular relationships in central retina of Macaque monkeys Macaca fascicularis. J Neurosci. Yamada E. Some structural features of the fovea centralis in the human retina. Arch Ophthal. Zhang HR. Scanning electron-microscopic study of corrosion casts on retinal and choroidal angioarchitecture in man and animals. Prog Ret Eye Res.

Helga Kolb. Skip to content Helga Kolb 1. Retina as seen through an opthalmoscope CLICK HERE to see an animation from the iris to the retina Quicktime movie A circular field of approximately 6 mm around the fovea is considered the central retina while beyond this is peripheral retina stretching to the ora serrata, 21 mm from the center of the retina fovea.

A schematic section through the human eye with a schematic enlargement of the retina The retina is approximately 0. Simple organization of the retina When an anatomist takes a vertical section of the retina and processes it for microscopic examination it becomes obvious that the retina is much more complex and contains many more nerve cell types than the simplistic scheme above had indicated.

Light micrograph of a vertical section through the O PL The second neuropil of the retina, is the inner plexiform layer IPL , and it functions as a relay station for the vertical-information-carrying nerve cells, the bipolar cells, to connect to ganglion cells Figs.

Light micrograph of a vertical section through the IPL 2. Light micrograph of a vertical section through human central retina Fig.

Light micrograph of a vertical section through human peripheral retina Central retina is cone-dominated retina whereas peripheral retina is rod-dominated. Thus in central retina the cones are closely spaced and the rods fewer in number between the cones Figs. The outer nuclear layer ONL , composed of the cell bodies of the rods and cones is about the same thickness in central and peripheral retina.

However in the peripheral the rod cell bodies outnumber the cone cell bodies while the reverse is true for central retina. In central retina, the cones have oblique axons displacing their cell bodies from their synaptic pedicles in the outer plexiform layer OPL. These oblique axons with accompanying Muller cell processes form a pale-staining fibrous-looking area known as the Henle fibre layer.

The latter layer is absent in peripheral retina. The inner nuclear layer INL is thicker in the central area of the retina compared with peripheral retina, due to a greater density of cone-connecting second-order neurons cone bipolar cells and smaller-field and more closely-spaced horizontal cells and amacrine cells concerned with the cone pathways Fig.

As we shall see later, cone-connected circuits of neurons are less convergent in that fewer cones impinge on second order neurons, than rods do in rod-connected pathways. A remarkable difference between central and peripheral retina can be seen in the relative thicknesses of the inner plexiform layers IPL , ganglion cell layers GCL and nerve fibre layer NFL Figs.

This is again due to the greater numbers and increased packing-density of ganglion cells needed for the cone pathways in the cone-dominant foveal retina as compared the rod-dominant peripheral retina. The greater number of ganglion cells means more synaptic interaction in a thicker IPL and greater numbers of ganglion cell axons coursing to the optic nerve in the nerve fibre layer Fig.

Muller glial cells. Vertical view of Golgi stained Muller glial cells Muller cells are the radial glial cells of the retina Fig. Throughout the retina the major blood vessels of the retinal vasculature supply the capillaries that run into the neural tissue. Capillaries are found running through all parts of the retina from the nerve fibre layer to the outer plexiform layer and even occasionally as high as in the outer nuclear layer.

Nutrients from the vasculature of the choriocapillaris cc behind the pigment epithelium layer supply the delicate photoreceptor layer. Foveal structure. Vertical section of the human fovea from Yamada Fig. Vertical section of the monkey fovea from Hageman and Johnson The fovea lies in the middle of the macula area of the retina to the temporal side of the optic nerve head Fig.

Tangential section through the human fovea Below this central micron diameter central foveal pit, the other layers of the retina are displaced concentrically leaving only the thinnest sheet of retina consisting of the cone cells and some of their cell bodies right and left sides of Figs. Macula lutea. Ophthalmoscopic appearance of the retina to show macula lutea Fig. If the retina is not surgically reattached as soon as possible, permanent and worsening vision loss can occur.

It's essential to keep your retina functioning properly to enjoy a lifetime of good eyesight. Many retina problems can be detected by your eye doctor before you notice any significant symptoms. Routine eye exams enable your eye doctor to examine your eyes for signs of macular degeneration and other serious retina problems so treatment can begin as soon as possible.

If you haven't had an eye exam recently, you can find an eye doctor here. If your eye doctor discovers a retinal detachment or other serious retina problem, he or she may refer you to an ophthalmologist who is a retina specialist for surgical or medical care. Remington, Lee Ann. Butterworth-Heinemann, The Johns Hopkins University Press, By Gary Heiting, OD. Schedule an exam Find Eye Doctor. The retina contains millions of light-sensitive cells rods and cones and other nerve cells that receive and organize visual information.

Your retina sends this information to your brain through your optic nerve, enabling you to see. Treatment is available for some retinal diseases. Depending on your condition, treatment goals may be to stop or slow the disease and preserve, improve or restore your vision.

Untreated, some retinal diseases can cause severe vision loss or blindness. It's important to pay attention to any changes in your vision and find care quickly. Seek immediate medical attention if you suddenly have floaters, flashes or reduced vision. These are warning signs of potentially serious retinal disease.

Retinal diseases care at Mayo Clinic. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.