Monday, September 15, 2008



What is Retina ?

Consider the eye to be a camera. The camera has a system of lenses in front which focus light on a film or digital sensors on the back. In the same way the eye has a system of lenses in front which focus light onto a layer at the back called the Retina. This layer has living sensors to sense the light form and send a signal to the brain which interprets these signals as the image we see. The retina is connected to the brain though a living cable which is called the optic nerve.

Retina has a very complex structure having ten layers. The light detector cells (photoreceptors) of the retina are called rods and cones. Cones help more with daylight vision and colour sensing whereas rods are primarily responsible for night vision or vision in low light conditions.

The central part of the retina called the macula has the maximum light sensitivity and resolution ability.

So any disease process which distorts the retina or makes it thicker/thinner or reduces the functional ability of the cells of the retina gravely affect the vision.

To diagnose various retinal diseases certain tests are done such as Fluorescein Angiography and Optical Coherence Tomography. These tests and some common retinal diseases are described in various sections.

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