Received: 11 June 2020
Accepted: 3 August 2020
First Online: 27 August 2020
Ethics approval and consent to participate
: The study was approved by the ethics committee of faculty of medicine, Cairo University. Reference number is not applicable. Informed written consents were obtained from guardian of children before the examination.
: All guardians of the children included in this research gave written informed consent to publish the data contained within this study.
: The authors declare that they have no competing interests.