Name one defect of vision that cannot be corrected by any type of spectacle lens. Explain in brief that defect. In a myopic eye, the image of a distant object is formed in front of retina and not at the retina itself. Why does this defect arise? [3 MARKS]

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Solution

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1. Cataract is a defect of vision which cannot be corrected by any type of spectacle lenses. It can only be corrected by surgical removal of the extra covering.
2. A cataract is a clouding of the lens in the eye leading to a decrease in vision. In cataract, an extra eyelid or an extra eye covering starts to grow underneath the eyelid.
3. The defect of Myopia may arise due to
(i) excessive curvature of the eye lens and/or
(ii) elongation of the eyeball.

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