Directions: Read the passage given below and answer the questions that follow.

Cataract is the major cause of blindness, which is also caused by a damage to the cornea. It occurs more often in old age. As one starts growing old, the lens of the eye hardens, loses its transparency and becomes opaque. It obstructs the light rays from entering the eye.

The onset of cataract blurs the vision. Sometimes, the cataract patient sees multiple images instead of a single object image. Because of the gradual development of cataract, the afflicted person loses his/her vision and the world becomes dark to him/her.

The development of cataract is a complex process. However, the following factors can be attributed to its formation. Cataract generally develops in old age but sometimes, children are born with cataract because of hereditary defect. Eye injuries too, can cause cataracts.

People exposed to sun rays for longer periods develop cataract earlier than others. Researchers opine that the smoke inhaled while smoking carries substances internally damaging the eyes. Ultraviolet radiation, invisible to the human eye, is linked to skin cancer. The victim loses vision and the world becomes dark to him.