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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
Name the defect of vision which makes the eye-lens cloudy resulting in blurred vision.
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?
The diagram alongside represents a section of a mammalian eye.
(i) Label the parts 1 to 5 of the diagram.
(ii) State the function of the parts labelled 4 and 5.
(iii) With the help of a diagram show the short sightedness.
In what two whys is a yellow spot different from the blind spot?
Due to elongation of _______ and increase in curvature of the eye lens, a person cannot see distant objects clearly.
Nearsightedness: elongated eyeball : : farsightedness: _______
Observe the given below the figure, correct it and explain and write about the concept depicted in this figure.
Myopia may arise due to ____________.
Observe the figure and answer the following questions:
- Name the defect of vision represented in the above figure.
- State the reasons for this defect.
- How is it corrected?
- Draw the diagram to show the correction of this defect.
