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Question
What is myopia?
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Solution
Myopia or near-sightedness is the defect of vision in which a human eye can see nearby objects distinctly but is unable to see distant objects clearly. In this case, the image of a distant object is formed in front of the retina instead of on the retina.
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RELATED QUESTIONS
Write the importance of ciliary muscles in the human eye. Name the defect of vision that arises due to gradual weakening of the ciliary muscles. What types of lenses are required by the person suffering from this defect to see the objects clearly?
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Do you know that the corneal-impairment can be cured by replacing the defective cornea with the cornea of the donated eye? How and why should we organise groups to motivate the community members to donate their eyes after death?
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long-sightedness?
Where is the near point of a person suffering from hypermetropia (or long-sightedness)?
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(ii) correction of short-sightedness by using a lens.
The defect of vision which cannot be corrected by using spectacles is:
(a) myopia
(b) presbyopia
(c) cataract
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- at infinity?
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The eye defect caused due to shortening of the eye ball from front to back.
Differentiate between members of the following pair with reference to what is asked in bracket.
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Differentiate between members of the following pair with reference to what is asked in the bracket.
Rods and cones (sensitivity).
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State the main functions of the following:
Tears
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(a) Name the defect of vision the person is suffering from and list its two possible causes.
(b) Draw a ray diagram to show the defect in the above case.
(c) Mention the type of lens used by him for the correction of the defect and calculate its power. Assume that the near point for the normal eye is 25 cm.
(d) Draw a labeled diagram for the correction of the defect in the above case.
Give Reason:
Older people require glasses to read and write.
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Short-sightedness and Long-sightedness.
Differentiate between:
Myopia and Hypermetropia.
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What type of lens is used to correct Astigmatism?
Complete the following sentence with appropriate word :
An inability to focus on nearby objects due to loss of elasticity of the lens with age is called Iris.
Choose the Odd One Out:
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- correction of myopia using an appropriate lens.
A person is unable to see clearly a poster fixed on a distant wall. He however sees it clearly when standing at a distance of about 2 m from the wall.
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Observe the following diagram and answer questions following it:
- Identify the defect of vision shown.
- List its two causes.
- Name the type of lens used for the correction of this defect.
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Given alongside is a diagram depicting a defect of the human eye. Study the same and answer the questions that follow:
 |
- Name the defect shown in the diagram.
- Give two possible reasons for this defect.
- Name the parts labelled 1 to 4.
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- Draw a labelled diagram to show how the above mentioned defect is rectified using the lens named above.
