You know what a “cataract” is in nature. It’s a great waterfall or downpouring of water. Now why should a certain kind of eye trouble also be called a “cataract?”

This is because in ancient times it was believed that this particular eye trouble was caused by an opaque film that came down like a cataract over the lens of the eye. A cataract of the eye is simply a cloudy or opaque discoloration within the lens of the eye. It may or may not interfere with vision. In fact, many people may have cataracts without knowing it.

The way people find out they have cataracts is when parts of the field of vision become blurred or cloudy. Another sign is when such a person can see better in the twilight than when the light is good. When there is less light the pupil is larger and this enables more light to enter the eye.

A cataract causes the pupil of the eye to appear gray or white instead of black. Among old people with cataracts, the pupils may become very small or contracted. When a person has total cataract, the entire lens of the eye becomes milky.

A cataract is generally regarded as a disease of old age. But a baby may have a cataract at birth, or in early childhood. Sometimes people get a cataract of the eye as a result of injury or from circulatory diseases.

When children have cataracts, it is possible to restore useful vision to the eyes by means of a surgical operation without removing the lenses of the eye. But usually when a cataract begins to impair the vision so that a person can’t carry on his normal activities an operation is necessary that will remove the lenses. This is done on one eye at a time to avoid a long period of total blindness.

A great many people who must have such an operation naturally worry about it quite a bit. But the fact is that a good eye surgeon can perform such an operation with very little risk of failure. After about six weeks, the eyes are fitted with glasses which enable the patient to see almost as well as he did with the lenses of his eyes.