My Daughter Is 5 Years Old. Since Last 2 Months

My daughter is 5 years old. Since last 2 months she complains of eye pain/strain the whole day but more while watching tv and studying. We got her checked and doctor said that cylindrical no. Is there but very mild, no need of glasses and gave victofol syrup. But her eyes still pain. She rarely complains by herself but whenever asked she says that yes they do pain. Don't know what to do. Kindly help