Question
Fri February 17, 2012 By:

Sir what is astigmatism?

Expert Reply
Fri February 17, 2012
We know that the shape of conea is spherical and it helps in the refraction of light to make the image at ratina . If the shape of the cornea changes horizontally or vertically , it causes in the focus of image at the ratina. For example if you are seeing asquare  mesh , the horizonatal or vertical lines of meash may not get focused on the ratina and you get the image of mesh in which vertical or horizontal lines are curved not straight.
 
It can be cured with the help of cylinderical lens. 
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