First of all, you should take him to the authority of the eye optometry medical institutions for eye examination to exclude eye diseases affect vision, then taking the medical optometry. After determining the correct proscription, you can choose the most suitable glasses for your son.
Kid glasses should choose lenses with good transmittance, and avoid inferior lenses to make myopia degree aggravate. From the perspective of safety, you should choose the non-breakable resin lenses instead of glass lenses, so as to avoid eye injuries caused by broken lenses.
You should pay attention to weight when choosing glasses for your son. Since the weight of the glasses are directly applied to the bridge of his nose, if it is too heavy, it may cause pain in the bridge of the nose. Therefore, their weight should generally under 20 grams that is the most appropriate.