Question

Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How does it help?

Answer 1

Sl. no.	Myopia (short-sightedness)	Hypermetropia (long-sightedness)
1.	A defect of vision because of which a person cannot see distant objects clearly.	A defect of vision because of which a person cannot see nearby objects clearly.
2.	The far point of a myopic eye is closer than infinity.	The near point of a hypermetropic eye is more than 25 cm away.
3.	Myopia occurs because the eye lens has a high converging power or because the eye ball is too long.	Hypermetropia occurs because the eye lens has a low converging power or because the eye ball is too short.
4.	A person suffering from myopia should wear spectacles with concave lenses as a concave lens decreases the converging power of the eye lens and therefore helps in forming the images of faraway objects on the retina of the myopic eye.	A person suffering from hypermetropia should wear spectacles with convex lenses as a convex lens increases the converging power of the eye lens and therefore helps in forming the images of nearby objects on the retina of the hypermetropic eye.