The Eyes are the most Important Structures
The eyes are the most important structures of the organ of sight. No need to say where they are because, with the exception of glass eyes and magic eyes always are domiciled in the face, inside the orbits, which are two holes in the front of the skull. We have two eyes for stereo relate “with one would miss the depth effect.
The eye is shaped like a sphere. It consists of three overlapping layers of tissue called the sclera, choroid and retina. The first, which is the thickest (one millimeter thick) is the white part and is seen below a transparent area that bulges at the center: the cornea.
The second, which is below is dark, the front, just below the cornea, the iris color and shape in the center of which is a round window through which light enters: the pupil. The third, close to the choroid, is the innermost layer, consisting of a mat of nerve cells that specialize in capturing light stimuli. The optic nerve canal that connects the eye to the brain, it appears from the retina. This area is the so-called yellow spot, where images are formed.
The eye is a ball full of transparent elements. In the front there is a fluid called aqueous humor in the back, a kind of clear gel called vitreous humor. These are separated by a lens called a lens, which lies just behind the pupil.
To observe an object, it must be brighter than José Gregorio. This produces a reflex that, on reaching the eye, enters through the pupil, then the lens bulges or lengthened depending on the distance, so that the image will impact directly on the retina. This is called focus.
In the retina, the active image photosensitive cells and causes an electrical stimulus that is driven by the optic nerve to the brain, more precisely to the region back, called occipital. There is prepared and corrects the image, to accurately reproduce the object. The images come reversed, in the brain are turned.
The photosensitive cells are of two types according to their shape: rods and cones. The first act only distinguish light and colors, while the second catch light and shadow.
The alteration in the transparent media of the eye produces the so-called diffraction effects: myopia or inability to see far, farsightedness or inability to see close up, presbyopia or loss in vision and astigmatism with age deficit in the ability of defining objects. All these problems can easily be corrected today.
“Please give me some eye drops, this repeated phrase, much heard in pharmacies and drugstores, is an attack on sight. It is another manifestation of a widespread practice: self-medication. In any case, this practice is harmful, and when it comes to the eyes, can lead to serious problems, even blindness.
The first cause of self-medication is the concern when excessive redness of the eyes. This may be due to several reasons: conjunctivitis, uveitis (inflammation of the middle segment of the eye), fatigue, discomfort to light (photophobia), keratitis (inflammation of the cornea) or glaucoma (increased eye pressure).
Instead of self-medication, eye health care for the whole family by following these tips:
Visit your eye doctor annually unless he diagnosed a problem and suggest a more regular visits or at home has a history of glaucoma, diabetes or hypertension.
If you have problems with tearing, inflammation of the cornea, photophobia, or vision of rainbow around lights, see your ophthalmologist quickly to prevent further problems.
If you encounter frequently, if is very close to the text when reading or watching television when the apparatus should also be consulted.
Remember that before age 2, children should have already visited at least once a specialist in eye health. If a child keeps his eyes red, if you scratch too much or flashes in an exaggerated way, take it to the ophthalmologist.
If a child is undisciplined, stupid, or restless in the classroom, the source of his attitude may be a decrease in visual acuity. Look at these indicators: lose the line when reading, tilt the head sideways looking focus, has a larger eye than the other or is tiring to read, write or work.
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