What are myopia and hypermetropia? With labelled diagrams, show each defect and explain how it is corrected.
How to lay out the answer. Follow the frame, then write it in your own words.
1 · Start with the normal eye. A normal eye sees clearly from infinity (far point) to 25 cm (near point), with the image on the retina.
2 · Explain myopia. Distant objects blur. The far point is closer than infinity, so the image of a far object forms in front of the retina.
3 · Draw myopia and its correction. [Sketch: parallel rays meet in front of the retina; then a concave lens spreads them so they meet on the retina]
4 · Explain hypermetropia. Near objects blur. This eye's near point lies beyond 25 cm, and rays from a near object would meet behind the retina.
5 · Draw hypermetropia and its correction. [Sketch: rays from a near object meet behind the retina; then a convex lens bends them so they meet on the retina]
6 · Link to daily life. Short-sighted people wear minus (concave) spectacles; long-sighted people wear plus (convex) ones for reading.
7 · Close. So a concave lens corrects myopia and a convex lens corrects hypermetropia.
Scoring tip: Draw the defective eye and the corrected eye side by side for each defect. Label the retina and the lens in every figure.
