Question

Describe various eye diseases in detail.

Answer 1

Common Eye Diseases:
The various eye diseases are as follows
1. Myopia:

• It is an eye disease which may occur to any person at any age.


• The person is unable to see distant objects clearly.


• It is caused either due to increased focal power of the lens (lens become more convex) or eyeball becomes larger.


• It is also called as short-sightedness. It can be corrected by use of biconcave lenses, which are also called as “minus lenses”.

2. Hypermetropia:

• It is also called farsightedness.


• The person is unable to see near objects clearly.


• It is caused either reduced focal power of the lens (lens becomes less convex) or the eyeball becomes smaller.


• It can be corrected by the uses of biconvex lenses which are also called as plus lenses.

3. Cataract:

• It is an eye disease of old age. The eye lens gradually becomes opaque, as a result, the light rays fail to enter into the eye.
• Surgical removal of the lens and either implantation of the artificial lens or use of spectacles with the convex lens is a corrective measure.

4. Astigmatism:

• It is due to the abnormal shape of the cornea, in which different curvature in different regions of cornea appears.


• It can be corrected by using cylindrical lenses.


• It can be corrected by the use of cylindrical lenses.

5. Conjunctivitis:

• This eye disease is caused due to viral or bacterial infection.


• There is inflammation & irritation in the conjunctiva. The conjunctiva also becomes red.

6. Colourblindness:
It is a hereditary eye disease. The gene for color blindness is a recessive gene present on the X-chromosome. It was first described by Horner. It is of 2 types –

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  1. Red-green colourblindness
  2. Blue -Yellow colourblindness
  3. Total colourblindness
  
  
  
  
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