human eye

CONCEPT-1- HUMAN EYE

2- HUMAN EYE PARTS3- EYE DEFECTS4- CARE OF EYE

Subject- ScienceClass- 9TH(2012-2013)

chapter- lighttopic- human eye

Teacher's name- R.S. RAM

HUMAN EYE

1- SCLERA2- CHOROID3- RETINA

LAYERS OF EYE

RETINAThe retina is the film of the eye. It converts light rays into electrical signals and sends them to the brain through the optic nerve. The sides of the retina are responsible for our peripheral vision. The center area, called the macula, is used for our fine central vision and color vision. The retina is where most the problems leading to vision loss Occur. Three of the leading causes of blindness, from retina damage, are Retinitis Pimentos, Macular Degeneration and Diabetic Retinopathy

IRISThis is the colored part of the eye: brown, green, blue, etc. It is a ring of muscle fibers located behind the cornea and in front of the lens. It contracts and expands, opening and closing the pupil, in response to the brightness of surrounding light. Just as the aperture in a camera protects the film from over exposure, the iris of the eye helps protect the sensitive retina.

LENSDuring modern cataract surgery the outer membrane of the lens is left in place. The artificial intraocular lens is placed in this sack

CORNEAThe cornea is a clear, dome-shaped surface that covers the front of the eye. It is the first and most powerful lens in the eye's optical system. To keep it transparent the cornea contains no blood vessels. Tears that flow over it and aqueous humor in the chamber behind it keep it nourished. When you hear of eye banks and eye transplants, it is the cornea that is being replaced. The cornea can be damaged from: accidents, infections, and genetic defects.

EYE DEFECTS1- MYOPIA2- HYPERMETROPIA3- CATARACT4- PRESBYOPIA5- ASTIGMATISM

HYPERMETROPIA Hypermetropia, also known as farsightedness,

long-sightedness, is a defect of vision caused by an imperfection in the eye (often when the eyeball is too short or the lens cannot become round enough), causing difficulty focusing on near objects, and in extreme cases causing a sufferer to be unable to focus on objects at any distance. As an object moves toward the eye, the eye must increase its optical power to keep the image in focus on the retina. If the power of the cornea and lens is insufficient, as in hyperopia, the image will appear blurred.

Image of Hypermetropia

MYOPIA Myopia, commonly known as being

nearsighted or shortsighted, is a condition of the eye where the light that comes in does not directly focus on the retina but in front of it. This causes the image that one sees when looking at a distant object to be out of focus, but in focus when looking at a close object.

Image of Myopia

CATARACT THE EYE LENS BECOMES OPAQUE.REMEDY- SURGICAL REMOVAL

CARE OF EYE1- DO NOT SEE VERY BRIGHT SOURCE

OF LIGHT2- DO NOT READ IN VERY DIM LIGHT3- WASH EYES WITH COLD WATER 4- DO NOT RUB EYES IN CASE ANY

THING HAS FALLEN IN.5- CONSULT EYE DOCTOR IN CASE OF

EYE PROBLEM.

THE END