1. Myopia or Short-sightedness: People having this eye defect can see near objects clearly but not distant objects. In this case, the lens of the eye is too convex and the rays of light are focused at a point in front of the retina instead of upon it. This defect is corrected by the use of concave lenses.

2. Hypermetropia or Long-sightedness: A farsighted person can see distant objects clearly but not near objects. In this case, the eyeball is too short so that the retina is too close to the lens and the focusing point lies behind the retina. It is corrected by the use of the convex lens.

3. Astigmatism: This abnormality of vision is due to the irregularities in the shape of the lens and cornea. The lens shows different curvatures in different regions of the eye. So the light rays are not brought into sharp focus on the retina. This defect is corrected by the cylindrical lens.

4. Presbyopia or Old-age Sight: It is due to the loss of flexibility of the lens in the old age. The person feels difficulty in focussing on near objects. This defect occurs at any time after the age of 35. It is corrected by the use of the convex lens.

5. Cataract: In this type of eye defect the lens becomes opaque due to several reasons. The person cannot see the objects clearly as the light rays do not pass through it. Surgical removal of the lens and its replacement by a convex lens is the only remedy for this disease.

6. Glaucoma: In this abnormality, the pressure within the eye is raised above the normal value i.e. 15-20 mm. The intraocular tension is increased which ultimately causes blindness.

Disorders of Ear:

1. Meniere’s Disease: Spinning or whirling vertigo (dizziness) is characteristic of Meniere's disease.

2. Otitis Media: This is an acute infection of the middle ear caused mainly by bacteria and associated with infection of the nose and throat.