16 June 2014

The Eye

How is it structured the eye
 The Eye

The rays of light entering the eye through the pupil through the crystal and generate our visual sensations.
 When the rays of light reaching the retina creating visual stimuli, which the optic nerve transforms it into electrical impulses, leading to the brain, where they are turned into images.
If the eye has no visual defect, the image of the object is formed correctly on the retina. Unlike the vision is blurred.
The retina is a thin tissue composed of two types of cells: rods and cones, specialized in the conversion from light stimulus to the nerve stimulus. The cones are concentrated on the fovea, a small depression in the retina with a high concentration of receptors, which allows you to see a clear picture and make the separation between the different colors. The rods have a complementary function to the cones, and operate in conditions of poor visibility (such as a dimly lit room, night vision ...).
How the eye works
The eye has a number of fine muscles that allow the eye to move quickly between objects at different distances. If the eye has no visual defects correctly records the light stimulus that will always be focused on the retina. So, you'll see clearly up close, from a distance and in the intermediate zone. If the focus point is placed in front of or behind the retina, the images are not clear and it becomes necessary to correct the optical adequate.
The most common visual defects are: hyperopia, myopia, presbyopia and astigmatism
 
Structure of the eye
The eye focuses the images near and far, enables three-dimensional vision and detects distances. It can be compared to a camera, example:
  • The cornea first organ to receive external images, plays the role of photographic lens.
  • The pupil opens and closes according to the brightness. It is located in the center of the iris color. is comparable to the aperture of the camera:
  • The crystalline lens is a lens that has the ability to change the curvature of its surface in function of the distance of the object to be observed. This action is called "accommodation." With age decreases its elasticity and its effectiveness of accommodation in near vision; a natural evolution that takes the name of presbyopia.
  • The vitreous humor represents 90% of the volume of the eye. E 'gelatinous, able to absorb shocks and maintain the retina (the nerve membrane on which images are formed) in its position. Over the years, its density is reduced, giving rise sometimes to the phenomenon of "floaters" (the perception of black specks in motion).we can compare it at the darkroom,
  • The aqueous humor is a liquid which keeps the pressure and the shape of the eyeball. E 'consists essentially of water, but also of vitamin C, glucose, lactic acid and protein.
  • The optic nerve transmits visual information to