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What is Power of Accomodation of Eye?
The ability of the eye lens to change its focal length is called power of accomadation
This focal length of eyes is changed with the help of
cillary muscles
as explained below
When eyes are looking at distant objects
Cillary muscles are relaxed
These pull the eye ligaments tightly
Due to this, eye lens become streched and become thin
So, focal length increases
When eyes are looking at nearby objects
Cillary muscles are contracted
Due to this, eye ligaments are loose
Eye lens become thick and we are able to see nearby objects
So, focal length decreases
What is Range of Accomodation reached by Normal Eye?
Human Eye can see objects whose distance is between Infinity and 25 cm from Normal Eye
What is Near and Far Point of Eye?
Farthest Point where eye can see is called Far Point of Eye
It is infinity
Nearest Point where eye can see is called Near Point of Eye
It is 25 Cm from eye
What Is Cataract?
In old age, crystalline lens of some people become milky and cloudy
This is called cataract
It causes partial or complete loss of vision
It can be avoided with the help of cataract surgery
Why we have 2 eyes for vision and not one?
It helps us to have wider view
With one eye, a human being can see a horizontal field view of 150 degrees
With 2 eyes, a human being can see a horizontal field view of 180 degrees
Explanation
Since both eyes are separated by a distance of few cm, both eyes see different images
Our brain is able to combine 2 images into one and hence we are able to see image with wider view
Hence, we are able to detect faint or far way objects because of our 2 eyes
Also,
It helps us judge distances accurately
Because our eyes are separated by a few centimetres, each eye sees the object from different angles.
So, the brain sees two slightly different image
The brain combines the two images into one, using the extra information to tell us how close or far away things are.
