The basic functions have been explained. Like a camera, the eyes have their very own optical system. The most important components of the eye are:
The light rays then penetrate further, all the way to the lens of the eye. It has a diameter of about 9 millimetres and is 4 millimetres thick. It is enveloped by the so-called ciliary muscle. It is kind of like the zoom in a camera.
When you look at something in the distance, the muscle is relatively relaxed. But when you look at your watch, the muscle tightens. As a result, the lens curves and the refraction power increases.
This is measured in dioptres. Close objects can be reproduced very sharply by the curved lens. Experts call this process accommodation. The ability to accommodate is very well pronounced particularly in a person’s younger years. Twelve-year-olds with healthy eyes can see objects extremely sharply up to a distance of 8 centimetres. In one’s forties, this distance is 17 centimetres, and in one’s seventies, it’s only approx. one metre.
By the way: 95 percent of our visual acuity conglomerates in one tiny point in the retina. This mite with a diameter of only 2 millimetres is called the macula, or the yellow spot. In the fovea – experts call it the central macula - the number of cones responsible for colour vision is very high. The point of sharpest vision is thus located in our retina.
Also found in the retina are the rods that are responsible for vision at twilight and at night. The vitreous body fills in the rear part of the eye and consists of a gel-like substance. It protects and supports the retina and eye. It has an elastic structure and functions like a shock absorber if pressure is suddenly exerted on the eyeball.
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