Eye Anatomy

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Eye Anatomy
Human eye ball is about 1 inch in diameter.
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Eye Parts

• Cornea
• Transparent, dome shaped covers iris pupil
• Refractive (bends light) very sensitive.
• Should be smooth
• Astigmatism if not smooth
• Light goes through the cornea first

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Eye Parts

• Iris
• Colored part of eye surrounding pupil
• A muscle that can shrink or grow depending on the
  amount of light present

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Eye Parts

• Pupil
• The space in the center of the iris
• Just a spaceshrinks or grows depending on the
  muscles of the iris
• Looks like a black dot
• Indicates amount of light present
• Indicates health

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Eye Parts

• Lens
• Transparent
• Refracts (bends light)
• Can change shape to focus (muscles on top and
  bottom)
• Can be replaced with a working lens if diseased

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Eye Parts

• Retina
• Takes up 2/3 of the inside back surface of the
  eye ball
• Contains rod and cone nerve cells- Rods help see
  light and dark- Cones help see colors
• Image falls on retina (inverted and smaller)
• Tears (rips) can be fixed with lasers

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Eye Parts

• Optic Nerve
• Connects the eye to the brain
• Blind spot is place where optic nerve is
  connected to the eye ball.

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Try these

• Blind spot
• Light bulb
• Optical illusions
• http//www.exploratorium.edu/learning_studio/cow_e
  ye/step01.html

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Common vision problems
Nearsightedness (myopia) This problem is often
discovered in school-age children who report
having trouble seeing the board.
Near-sightedness usually becomes progressively
worse through adolescence and stabilizes in early
adulthood. It is an inherited problem.
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Nearsightedness
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How to correct nearsightedness

• If the image needs to be stretched out to reach
  the correct point on the retina, which kind of
  lens is needed to correct this?

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Common vision problems
Farsightedness (hyperopia) This vision problem
occurs when light rays entering the eye focus
behind the retina, rather than directly on it.
The eyeball of a farsighted person is shorter
than normal. Many children are born with
hyperopia, and some of them "outgrow" it as the
eyeball lengthens with normal growth.
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Farsightedness
People who are farsighted have need to move
printed matter farther from them in order to
focus it. Usually occurs in middle age age 40.
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How to correct hyperopia

• If the image needs to be shrunk to reach the
  correct point on the retina, which kind of lens
  is needed to correct this?