Ethical consideration
This study was approved by the Ethical Committee of the Faculty of Medicine, Ankara University (decision no. 25-503), the reviewboard of the Turkish Republic Ministry of Education and school management. Initially, a voluntary informed consent form were sent to the parents; children whose parents agreed to participate were selected. An informed consent form was read to the children participating in the study. In this way, verbal and written approval was obtained. The results of the screening were informed to parents and the parents of children who had problems were advised to consult a health center.