(b) A student sitting at the back bench in a class has difficulty in reading. What could be his defect of vision? Draw ray diagrams to illustrate the image formation of the blackboard when he is seated at the (i) back seat (ii) front seat. State two possible causes of this defect. Explain the method of correcting this defect with the help of a ray diagram.
Answers
1 The boy is suffering from myopia
2 the boy is suffering from hypermetropia
Answer
Vision defect: Myopia
Myopia is a vision condition in which one sees objects that are near to you with clarity but objects that are far away seem to be blurry. It occurs when the shape of the eye makes light rays to refract focusing image in front of retina .
Myopia occurs when the eyeball is too long. This causes light rays to focus at a point of the retina instead of directly on it's surface.
Also when cornea is too curved for the length of the eyeballs.
Myopia begins in childhood and stabilizes in early adulthood but it continues to progress with age.
Treatment of Myopia
It can be corrected with eye classes, contact lenses or refractive surgery depending on the degree or stage of myopia