Q1. The least distance of distinct vision, or the near point, for a normal eye is taken as 25 cm. This distance increases to 50 cm for an elderly person. If the person tries to read a book at about 25 cm from the eye, the image appears blurred. This defect of vision of the eye is called:
Explanation
Presbyopia is the age-related loss of the eye's power of accommodation, so the near point moves farther away and close objects become blurred. That is exactly described when the near point increases from 25 cm to 50 cm in an elderly person. Hypermetropia also causes difficulty in seeing nearby objects, but the age-linked weakening of accommodation points specifically to presbyopia. Myopia affects distant vision, not near reading. Astigmatism is caused by unequal curvature of the cornea or lens and produces distorted vision, not this near-point shift.