(a) A myopic person sees clearly only up to 2 m. What spectacle power is needed for distant vision? (b) A hypermetropic person has near point 1.0 m; what reading glasses let them read at 25 cm? (c) Explain why a 60-year-old typically needs reading glasses. Step 1: For distant objects the diverging lens must form a virtual image at the person's far point (2 m). Object at infinity, image at v = −2 m (virtual, same side). 1/f = 1/v − 1/u = −1/2 − 0 → f = −2 m → P = −0.5 D. A −0.5 D concave lens. Step 2: Object at u = −0.25 m must image at the near point v = −1.0 m. 1/f = 1/v − 1/u = −1/1.0 + 1/0.25 = −1 + 4 = 3 → f = +0.333 m → P = +3.0 D convex reading glasses. Step 3: Presbyopia: the crystalline lens stiffens with age and ciliary muscles weaken, so maximum accommodation falls; the near point recedes from 25 cm (youth) past ~1 m by age 60. The eye can no longer add enough converging power for near work, so a +2 to +3 D convex "add" supplies it externally.