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DEFECTS OF VISION
Ushakumari.V
Christ nagar senior secondary school
Thiruvallom
EYES- OUR WINDOWS TO THE WORLD!
Spectacles
?????
WHY SO
????
DEFECTS OF VISION
 When normal functioning
of the eye is affected , it
results in defects of
vision
 Mainly 2 types
 My...
NORMAL EYE
In a normal eye , light passes through the
cornea , and the image is focused by the lens on
the retina
WHAT IS THE DIFFICULY HERE????????
MYOPIA- NEARSIGHTEDNESS
 A person can see nearby objects clearly and
distinctly but cannot see far away objects clearly.
...
MYOPIC EYE
MYOPIC EYE-IMAGE FORMATION
MYOPIC EYE – RAY DIAGRAM &
CORRECTION USING CONCAVE LENS
CAN YOU SEE PROPERLY ?????
HYPERMETROPIA – FAR SIGHTEDNESS
 The person can see distant objects clearly and distinctly
but cannot see nearby objects ...
HYPERMETROPIC EYE
HYPERMETROPIC EYE – IMAGE
FORMATION
HYPERMETROPIC EYE – RAY DIAGRAM
AND CORRECTION USING CONVEX LENS
SUMMING
UP ….
Defects of vision
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Defects of vision

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Defects of vision

  1. 1. DEFECTS OF VISION Ushakumari.V Christ nagar senior secondary school Thiruvallom
  2. 2. EYES- OUR WINDOWS TO THE WORLD!
  3. 3. Spectacles ????? WHY SO ????
  4. 4. DEFECTS OF VISION  When normal functioning of the eye is affected , it results in defects of vision  Mainly 2 types  Myopia (short sightedness)  Hypermetropia (long sightedness)
  5. 5. NORMAL EYE In a normal eye , light passes through the cornea , and the image is focused by the lens on the retina
  6. 6. WHAT IS THE DIFFICULY HERE????????
  7. 7. MYOPIA- NEARSIGHTEDNESS  A person can see nearby objects clearly and distinctly but cannot see far away objects clearly.  In myopic eye ,the image is formed in front of the retina.  Caused by two reasons:  Elongation of the eyeball  so images are focused in front of the retina  Decrease in the focal length of eye lens  Correction: by using a concave lens of appropriate power.
  8. 8. MYOPIC EYE
  9. 9. MYOPIC EYE-IMAGE FORMATION
  10. 10. MYOPIC EYE – RAY DIAGRAM & CORRECTION USING CONCAVE LENS
  11. 11. CAN YOU SEE PROPERLY ?????
  12. 12. HYPERMETROPIA – FAR SIGHTEDNESS  The person can see distant objects clearly and distinctly but cannot see nearby objects clearly  The image is focused behind the retina  Main causes are :  Shortening of the eyeball  So the images are focused behind the retina  Increase in focal length of the eye lens  Correction: by using a convex lens of appropriate power
  13. 13. HYPERMETROPIC EYE
  14. 14. HYPERMETROPIC EYE – IMAGE FORMATION
  15. 15. HYPERMETROPIC EYE – RAY DIAGRAM AND CORRECTION USING CONVEX LENS
  16. 16. SUMMING UP ….

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