Eyes are designed for distance vision, so when one looks at something up close the focusing system in the eye, or crystalline lens, has to be engaged in order for that near object to be seen clearly. The ability do to this directly impacts our ability to read, write, take tests and take notes in class. If the child can not move from far to near or near to far efficiently, school performance can be greatly affected. Similarly, if focus can not be maintained for reasonable periods of time at the near point, strain occurs, the eyes will become fatigued and the print will get progressively blurry. Sometimes children with focusing problems will develop headaches, hold their book closely or lay their heads down on their desk.