Question

a person uses a lens of power -1.0D for correcting his distant vision and for correcting his near vision he use alens of power +2.0D.calculating the focal lenght of the lens required to correct this defects. explain why a normal eye is not able to see clearly the object placed closer than the near point?

Answer 1

1. For distant vision:

f= -1m

2. For near vision:

f= 1/2 m

Normal eye is not able to see clearly when the object is placed closer than the near point because in this case the size of iris is not control pupil doesn't able to adjust iris and due to this power of accomadation is very low. so, normal eye cannot see object clearly.

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