A myopic adult has a far point at 0.1 m. His power of accommodation is 4 diopters. (i) What power lenses are required to see distant objects? (ii) What is his near point without glasses? (iii) What is his near point with glasses? (Take the image distance from the lens of the eye to the retina to be 2 cm.)
(i) The power of the lens to see distant objects is 
(ii) Near point of his eyes without glasses is 0.07 m
(iii) Near point of his eyes without glasses is 0.25 m
Given:
The focal length of the myopic adult is 0.1 m; the power of accommodation is given as 4 diopters. The image distance is 2 cm or 0.02 m.
Formula used:
Lens power formula: The unit of refractive power of the lens is measure in diopter, which is the reciprocal of focal length of the lens.
where
P is the power of lens, unit is called diopter (d) and f is the focal length of the lens.
Explanation:
(i) To find the power of the lens to see distant object
Power to see finite distance object with normal eye
Power to see infinite distance object with corrective lens
Now the power of the lens on to see distant object
(ii) To find his near point without glasses
The power of the normal eye is 
The near point of the eyes is = 
(iii) To find his near point with glasses
The near point of the eyes is = 
