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. 
• Cataract disease is also known as salad motia.
• 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.