Disease: Retinal Detachment

    Retinal detachment facts

    • A retinal detachment is a separation of the retina from its attachments to the underlying tissue within the eye.
    • Most retinal detachments are a result of a retinal break, hole, or tear. Most retinal breaks, holes, or tears are not the result of trauma, but are due to preexisting factors such as high levels of myopia and prior ocular surgery.
    • Flashing lights and floaters may be the initial symptoms of a retinal detachment or of a retinal tear that precedes the detachment itself.
    • Early diagnosis and repair of retinal detachments are urgent since visual improvement is much greater when the retina is repaired before the macula or central area is detached.
    • The surgical repair of a retinal detachment is usually successful in reattaching the retina.

    What is the retina?

    The retina is an extremely thin tissue that lines the inside of the back of the eye. When we look around, light from the objects we are trying to see enters the eye. The light image is focused onto the retina by both the cornea and the lens. This light striking the retina causes a complex biochemical change within layers of the retina and this, in turn, stimulates an electrical response in other layers of the retina. Nerve endings within the retina transmit these electrical signals to the brain through the optic nerve. Within specific areas of the brain, this electrical energy is processed to allow us both to see and to understand what we are seeing. The retina has been compared to the film of a camera. However, once used, film has a permanent image on it. The retina continually renews itself chemically and electrically, allowing us to see millions of different images every day without them being superimposed.

    The retina is about the size of a postage stamp. It consists of a central area called the macula and a much larger peripheral area of the retina. The light receptor cells within the retina are of two types, called the rods and the cones. Rods allow us to see in conditions of reduced illumination. Cones provide us with sharpness of vision and color vision. The peripheral retina allows us to see objects on either side (peripheral vision) and, therefore, provides the vision needed for a person to move about safely. Since this part of the retina contains a lesser concentration of cones, it does not allow for perception of visual detail. Its larger concentration of rods provides better vision during conditions of darkness.

    In contrast, the macula is a smaller, central area of the retina that contains a high concentration of cones. Accordingly, it enables clear central vision to see fine details for such activities as reading or threading a needle. The macula is particularly sensitive to circulatory changes, especially those that occur with aging, such as decreased blood flow. The retina contains a network of branching arteries, which supplies blood that carries the needed oxygen and nutrients to the retina, and a network of accompanying veins, which then carry the blood away together with the waste products of retinal metabolism.

    Source: http://www.rxlist.com

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