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The Eye Anatomy
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The structure of the eye resembles a camera.It contains image-projecting organs, the refractive media: cornea and lens. The image-receiving organ is the retina.
The front cover of the lens of the camera is analogous to the cornea of the eye, which is the clear part you see when looking at someone's eye. The iris of the eye (the colored part) is analogous to the iris of a camera, and opens and closes depending upon the light. If there is low light, the iris opens wide to allow more light to enter. If there is a lot of light, the iris closes to decrease the amount of light entering the eye. Similarly, a camera adjusts its iris when you take a picture to avoid over exposure or under exposure of the film. The lens of the eye is similar to the lens of the camera, in that it focuses the image on the back of the eye. The vitreous cavity in the eye is analogous to the body of the camera, the "box" of the eye itself and is filled with a clear tissue "gel" called vitreous. The retina, the most important part of the eye from a retinal surgeon’s point of view (!) is analogous to the film in the camera. The retina has to be functioning properly to send a message to your brain to "take the picture."
The central portion of the retina, where you focus the image, is the macula. It is roughly the area inside of the arcade vessels, which extend from the optic nerve around the center part of vision. The true focal point of the eye is the foveal avascular zone (FAZ), which is only 400 microns wide (0.4mm). It is this small area that allows you to read, discriminate objects, etc. If damage is inflicted on this very small portion of the retina, then reading vision and focusing is lost. |
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