Defects of vision
-
Upload
ushavpillai -
Category
Documents
-
view
599 -
download
0
Transcript of Defects of vision
![Page 1: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/1.jpg)
DEFECTS OF VISION
Ushakumari.VChrist nagar senior secondary school
Thiruvallom
![Page 2: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/2.jpg)
EYES- OUR WINDOWS TO THE WORLD!
![Page 3: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/3.jpg)
Spectacles
?????WHY
SO ????
![Page 4: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/4.jpg)
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)
![Page 5: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/5.jpg)
NORMAL EYE
In a normal eye , light passes through the cornea , and the image is focused by the lens on the retina
![Page 6: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/6.jpg)
WHAT IS THE DIFFICULY HERE????????
![Page 7: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/7.jpg)
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.
![Page 8: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/8.jpg)
MYOPIC EYE
![Page 9: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/9.jpg)
MYOPIC EYE-IMAGE FORMATION
![Page 10: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/10.jpg)
MYOPIC EYE – RAY DIAGRAM & CORRECTION USING CONCAVE LENS
![Page 11: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/11.jpg)
CAN YOU SEE PROPERLY ?????
![Page 12: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/12.jpg)
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
![Page 13: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/13.jpg)
HYPERMETROPIC EYE
![Page 14: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/14.jpg)
HYPERMETROPIC EYE – IMAGE FORMATION
![Page 15: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/15.jpg)
HYPERMETROPIC EYE – RAY DIAGRAM AND CORRECTION USING CONVEX LENS
![Page 16: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/16.jpg)
SUMMING UP ….
![Page 17: Defects of vision](https://reader035.fdocuments.in/reader035/viewer/2022070316/555ee41fd8b42a772f8b58f6/html5/thumbnails/17.jpg)