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PRERNA SUBRAMANIAN

X-C

25

PRESENTATION

Scientific Skills

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EyelidsUpper and lower eyelids protect the front of your eyeball (orbit) by blockingforeign objects and bright light that can damage your eye. Your eyelids

involuntarily open and close (blink) every few seconds to help protect your eyeball. You can, of course, blink intentionally as well.With each blink, tear fluid (fluid arising from tear glands around the eye)passes over the cornea and lubricates the surface of the eye. This helpswash away germs, dust, eyelashes or other foreign objects and helps keepyour eyes from drying.

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The front of your eyeThere are three parts to the front of your eye:Sclera. The white of your eye (sclera) is the tough outer wall that

helps maintain the spherical shape of your eyeball. The sclera helpsprotect the delicate internal structures of your eye.

Pupil. The pupil is the dark spot at the center of your eye that allows

light to pass into the back part of your eye. Its size varies depending onthe extent of dilation and contraction of the iris.Iris. The iris is the colored part of your eye, which contains a ring of

muscle fibers that can expand or contract the size of your pupil, thushelping to control the amount of light entering your eyeball.A thin transparent tissue called the conjunctiva covers the sclera. Theblood vessels that are often visible in the white part of your eye arelocated within the conjunctiva.

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Your inner eyeBehind the scenes, other parts of your eye work to help you see:Cornea. Your cornea is a protective dome of clear tissue at the front of your eye. It functions as a convex surface that helps focus the light raysbefore they are fine-tuned by the lens.Lens. Your lens is a clear, elliptical structure about the size and shape of an M&M candy. The curvature of your lens changes to sharpen the focusof whatever you're looking at.Vitreous cavity. The vitreous cavity extends from the back of the lens tothe back of your eyeball. It's filled with a clear, jelly-like substance thatallows light to pass through. It also maintains the shape of your eyeball.

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The back of your eyeStructures at the back of your eye include the:Retina. Your retina is a thin layer of tissue that lines the back inner wall of your eyeball. Your retina consists of millions of light-sensitive cells and nerve cellsthat capture the images focused onto them by your cornea and lens. When

light hits these cells, electrical impulses are generated and carried to your optic nerve.Macula. Your macula is a specialized part of the retina. This patch of denselypacked light-sensitive cells is essential to your central vision and allows youto see fine detail.Optic nerve. Your optic nerve contains more than 1 million nerve fibers. Thesefibers carry information gathered by your retina to your brain.

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H ow your eyes moveEach eyeball has six muscles attached to the sclera. Five are seen from thisangle. These muscles allow you to move your eye and track an object withoutnecessarily turning your head. The eye muscles, working individually or together, allow you to shift your field of gaze left, right, up, down anddiagonally. Your brain coordinates the eye movements so that both eyes canmove together when tracking an object.

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For I dipped int o the futu r e, fa r as human eyeco uld see, Saw the visi o n o f the w or ld, and all thewo nde r that w o uld be

Alf r ed, L or d Tennys o n

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Donate Eyes to gift theEyesDo not buryThey can

give vision to the needy

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. It is unfortunatethat about 10 lakhcitizens of ourcountry aresuffering fromcorneal blindnessand majority are inthe younger group.

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. A ll religions and communities favor eye

donation

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.

T herefore, do not burn or bury your eyes after death,

for your eyes can give light and visionto 2 blind people if you pledge your eyes.

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