Hypermetropia (far-sightedness)

In a hypermetropic eye, light from a nearby object would meet behind the retina. So the near point moves farther away than the normal 25 cm. There are two causes. The eyeball may be too short, or the eye lens may be too flat, so its focal length is too long.

The fix is a convex lens, one that is thicker in the middle. It adds the extra focusing the eye cannot provide.

A small example

A person reads clearly only when the page is 75 cm away. The lens must make a page at 25 cm appear to be at 75 cm. So u = -0.25 m and v = -0.75 m.

• 1/f = 1/v - 1/u = 1/(-0.75 m) - 1/(-0.25 m).
• 1/f = -1.33 m⁻¹ + 4 m⁻¹ = +2.67 m⁻¹.
• So the power is P = +2.67 D. The plus sign confirms a convex lens.

Where marks go

In CBSE, Question 39 of the 2026-27 sample paper for visually impaired students asks about this defect in words. The 2026-27 Science marking scheme gives 1 mark for the meaning and 1 for the convex lens. The reasons carry 2 marks. If ray diagrams are asked for, draw both the defect and its correction, with the rays and parts labelled.

In ICSE, the 2027 specimen paper asks for the reason for hyperopia and how it is corrected, for 2 marks. The draft marking scheme wants the cause, a short eyeball or a flat lens, and the cure, a convex lens. Give both halves. Keep it apart from myopia.

About the author

Deepti Sardana

Founder Member & Academic Lead

An IIT alumna (M.Sc., M.Phil.) with over 25 years in teaching, child psychology and learning assessment. As Academic Lead at EduBrahma, she leads the method TRUtesting uses to find where and why a child loses marks.

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