By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) - There are many causes of a headache but one of the most commonly overlooked is poor vision that is not treated with glasses. The group that is most affected are children in grade school.

The problem is often detected this time of year. A young child is sitting in class and can’t see the board that well. They strain to see the board class after class and get headaches. The reason that it gets detected is not often the result of headache. Actually it is because of poor school performance.

Eventually difficulty seeing the board leads to poorer school performance. But if you notice your child is having headaches one of the things to think of is poor vision.