Stay-at-home mum Naomi was keeping a close watch on her two boys, one in primary school and the other in secondary, and particularly on their eyes.She was concerned as they spent an increasing amount of time using digital devices after the coronavirus pandemic triggered class suspensions and the need to study online at home.The Japanese native living in Hong Kong asked to remain anonymous so that other parents would not judge her harshly as they sometimes do on social media support groups in…