(Jrt)
1. posterior chamber (filled with vitreous humor), 2. ora serrata, 3. cilliaire muscle, 4. suspensory ligament, 5. Schlemm canal, 6. ward, 7. anterior chamber (filled with aqueous humor), 8. cornea, 9. iris, 10. cortical lens, 11. nucleus of the lens, 12. cilliaire body, 13. conjunctiva, 14. oblique muscle below 15. muscle right below 16. muscle right median, 17. Retinal veins and arteries, 18. optic papilla or blind spot, 19. blade riddled, 20. Retinal central artery, 21. Central Retinal vein, 22. optic nerve, 23. vortiqueuse vein, 24. tissue, 25. macula, 26. fovea, 27. sclera, 28. choroid, 29. right upper muscle, 30. retina.
Eye
The eye (plural eyes) is the organ of vision ie the body senses that allows an animal to analyze the light to interact with its environment.
In the animal world, there are at least forty types of visual organs known as "eyes". This diversity poses the question of the origin of visual perception. The eyes are the easiest just able to detect the difference between light and dark eyes while the more complex as the human eyes can distinguish shapes and colors.
A major goal of contemporary technology is to make "electronic eye" that can match or even exceed the ability of eyes that exist in the world living, for example, replace the eye of a person which would have been an accident.
Anatomy and Physiology (human eye)
The eye adapts first to ambient light. The man can perceive with a sensitivity equivalent sunlight or the light of the full moon, either with a light 10 000 times less. An adaptation from the first gauge of the iris that night mode can reach a maximum aperture of 7 mm for young people (maximum 4 mm decreases with age).
Like most mammals, birds, reptiles and fish, the human eye consists of an eyeball, made of 3 envelopes: the sclera, the uvée, and the retina (from outside to inside).
Previous
* The cornea, anterior part of the eyeball is a transparent lens whose role is to capture and focus the light on the lens.
* Aqueous humor, located between the posterior surface of the cornea in front and the front of the lens back.
* The uvae composed of the iris (allowing the modification of the incoming light), the choroid and the ciliary body;
* The ward is the hole in the center of the iris;
* The crystalline lens used for biological accommodation ( "finalization" on the item to view to get a point object focal point image on the retina) is connected to the ciliary body through the zonula;
Posterior
* Retina, the membrane composed of nerve photoreceptor cells called rods and cones, for the transformation of electromagnetic waves into electrical impulses for processing images via the nervous system;
* The choroid, Foodland membrane of the retina and true "vascular sponge" that lines the inside of the eye.
* The sclera.
* The vitreous.
The annexes of the eye
There are four:
1. The orbit bone cavity, covered with a fibro-elastic membrane (the periorbite). Protective role.
2. Oculomotor muscles, the role of travel. The number 6 in humans:
1. 4 muscles rights: the right upper right lower domestic law (or medial) and right external (or side);
2. 2 oblique muscles: large oblique (oblique or higher) and small oblique (oblique or lower)
3. The lid, allowing isolation membrane more or less electromagnetic radiation, spreading the film of tears and protection of the cornea.
4. Lacrimal gland: at the top and outside, the secret 40% of our tears, the rest being secreted by glands accessories.
The receivers of the eye
The receivers of the eye used to decompose the information light into electrical signals to be sent to the optic nerve.
* In humans, there are 3 types of cones (red, green, blue) to decompose light in color. They are four in some reptiles and birds. They can detect ultraviolet and their cones do not detect quite the same colors.
* Sticks limited to light, faster and more sensitive than cones.
The tissues of the eye
Like most mammals, birds, reptiles and fish, the human eye consists of an eyeball, comprising:
* The cornea, anterior eyeball lens, it is the window of the eye
* The sclera or sclera.
Color the human eye
A genetic mutation of the gene OCA2, carried by chromosome 15 is responsible for blue eyes and date to about 8000 years. It is due to a single common ancestor and has endured.
OCA2 code P protein is involved in the production of melanin, the pigment that colors hair, skin and eyes. The mutation is not situated directly on OCA2 but adjacent to a gene that n'annihile not entirely his activity but limits its scope by reducing the production of melanin in the iris. When the gene is totally disabled, the body does not secret any more melanin is the albinism.
Diseases of the eye
The ophthalmology is the science which studies the eye. All parts of the eye may be affected:
* Muscles oculomotor: Diplopia, paresis or paralysis of muscles.
* Orbit: enophtalmie, exophthalmos so.
* Eyelid: ptosis, ectropion, entropion, stye, blepharitis, tumor, lagophtalmie, distichiasis, Chalazion, etc..
* Tear occurred: dacryoadenite, canaliculite, Dacryocystitis so.
* Conjunctiva: conjunctivitis (bacterial, fungal, viral or parasitic), pinguécula, etc. Pterygium.
* Sclere: scleritis, scleromalacie perforating or not, so blue sclera.
* Cornea: keratitis (bacterial, fungal, viral or parasitic), Keratoconus, gérontoxon so.
* Uvae: uveitis, etc. coloboma.
* Pupil sets, mydriasis (dilated) in miosis (contracted), irregular (whose origin is often an inflammation of the iris past or present)
* Lens: cataract, ectopia, myopia, aphakie, etc. presbyopia.
* Glass: hemorrhage, so delamination.
* Retina tear, detachment, arterial or venous occlusion, degeneration (macular degeneration related to age), retinitis (retinitis pigmentosa) and so on.
* Optic nerve: optic neuritis, papillary edema, glaucoma
* Strabismus
Optical operation
The first model of the eye, said "reduced eye" is to be considered a spherical Creedmoor, with a diaphragm and to be placed in conditions allowing the stigma Gauss approached. This model enables us to understand the formation of images on the retina and the effect of the curvature (amended by the lens) for the accommodation.
The practical model used in experimental activities is to model the retina by a flat panel display (blank sheet) and the crystalline lens by a convergent.
In some devices teaching the lens is a lens made of a flexible plastic membrane that can be more or less fill with water. It can show the accommodation and address the concepts of punctum proximum and punctum remotum.
The use of a glass lens, can model the normal eye (emmetropia, clear vision to infinity without accommodation) then, by changing the lens-screen distance, modeling myopia (screen too distant) and 'hyperopia (screen too close), then with the possibility of adding a corrective lens to model glasses.
The eye can be reduced to a system centered whose characteristics include:
* Focal length picture: 22 mm
* Focal object: -17 mm
* Distance (home object → front of the cornea): +15 mm
o therefore distance (anterior surface of the cornea plans → main): +2 mm
o therefore distance (anterior surface of the cornea → retina): +24 mm
* Radius of curvature +6 mm
* Power: D = 60 δ
* Refractive index n = 1.337
* Accommodation: AC = 6.667
* Minimum separable: αmin = 1 '
Read also Color Blindness
wikipedia
