Hello It seems from the history that your 4 year old son is having refractive error and he is advised to wear spectacles. The refractive errors are common problems in childhood. The treatment is by use of spectacles. The refractive errors are known to increase or decrease quickly because of growth of eye ball in children. Hence he requires to use the glasses regularly and need to get eye examination once in 6 months to find out any variations. He should be given vitamin A rich foods which are essential for healthy eyes. But the refractive error is not known to disappear completely hence he need to use spectacles. Thank you