A cataract is an ophthalmological condition which results in the eye's lens becoming cloudy. A person who develops a cataract usually finds that their vision in the affected eye becomes blurred or cloudy. They may also see halos when they look directly at bright lights. Here is a brief explanation of this condition.
There are several things that can increase a person's risk of developing cataracts. These include having diabetes and having a family history of this condition.
Many schools offer vision screening, and you can also do these basic tests at home. A basic screening just refers to the traditional test where you stand in front of a chart and read the letters on it. This test can be a useful way to note any issues with long range vision.
However, you shouldn't rely on this type of screening to diagnosis all visual issues with your child. Rather, you should take your child to the optometrist.