Suggest Treatment For My Son S Vision Prolem

My son is five years old. Recently he had refraction done with mild allergies. Two different M.S. optho suggested That there is no refractive error and prescribed anti allergic eye drops only. But two days back His Madam In the school complained that he could not note down the task given on the blackboard. He has to bring closer to the b.board to see the task. Today I asked him to read the letters on the computer screen. He misread it. I want to know what to do and to go for further checkup with latest technologies to clear the refractive error if any.