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प्रश्न
Enumerate the common defects of vision, their causes and the possible methods of correcting them.
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उत्तर
| Defect of vision | Cause | Corrective measure |
| Myopia | Lengthening of eye ball from front to back or the lens is too curved. | Using suitable concave lens |
| Hyperopia | Shortening of eye ball from front to back or the lens is too flat. | Using suitable convex lens |
| Astigmatism | Uneven curvature of the cornea | Using suitable cylindrical lenses |
| Presbyopia | Loss of flexibility of lens | Using suitable convex lens |
| Cataract | Lens turning opaque | Surgery or use of convex lens or implantation of plastic lens. |
| Colour blindness | Genetic defect | No control measure |
| Squint | Formation of cross-eye | Surgery and suitable exercise |
संबंधित प्रश्न
the biological/technical terms for the lens of eye losing flexibility resulting in a kind of long-sightedness in middle aged people.
What is the far point of a person suffering from myopia (or short-sightedness)?
Differentiate between myopia and hypermetropia. What type of spectacles should be worn by a person having the defects of myopia as well as hypermetropia? How does it help?
A student cannot see a chart hanging on a wall placed at a distance of 3 m from him. Name the defect of vision he is suffering from. How can it be corrected? Draw ray diagrams for the (i) defect of vision and also (ii) for its correction.
Observer the following diagram and answer the questions.
a) Which eye defect is shown in this diagram?
b) What are the possible reasons for this eye defect?
c) How this defect is corrected, write it in brief?
In what two whys is a yellow spot different from the blind spot?
Explain the Term: Cataract
Give Technical Term:
The type of lens used to correct myopia is
Given below is a diagrammatic representation of a defect of the human eye:
(i) Identify the defect.
(ii) Mention two reasons for the above defect.
(iii) State how the defect can be rectified.
(iv) Name the part of the eye responsible for maintaining the shape of the eyeball.
Myopia and hypermetropia can be corrected by:
