The senses Eye Contour
The one of our most precious sense receptors in the human body. While looking at objects light enters the eyeball through the lens of the eye it is focused on the back of the eye wall and rods and cones convert the light into electrical impulses which are sent to the brain to be processed. While looking at distant objects, the cillary muscle is normally relaxed which gives the lens a slightly curved shape. While focusing on near objects the cillary muscle must contract to bring objects closer into focus on the back of the eye wall. The lens of the eye bulges and curves more when the cillary muscles is contracted.
As we grow older it is simply the prolonged use of the muscle and the curvature of the lens that changes making it more likely that we will be farsighted as we age. The elasticity in the lens and surrounding tissues loosens making it harder for us to get objects into focus as we age. Farsightedness is the condition involving the fact that the lenses can no longer bulge enough to bring near objects into focus, another name for this condition is presbyopia.
Cataracts are caused by the lens becoming hard, it looses its transparency and becomes milky in appearance. Prolonged exposure to Ultravolet Radation is the primary cause of someone getting cataracts. The primary treatment for cataracts is to simply replace the lens of the eye.
The innermost layer of the eyeball is called the Retina. The Retina is a layer where the rods and cones can be found on the back wall of the eyeball. Rods and cones are the two types of microscopic photoreceptors cells. Rods and cones get there names primarily due to there shape. The Rods stimulate cells in dim light and are for night vision. Cones are stimulated by fairly bright light and are cells for vision in daytime.
