Hello, Do not let him skip breakfasts or meals. Dehydration and lack of nutrition often leads to headaches or migraine. Migraines can cause blurry vision, and sometimes come with unusual sensations in the mouth. Missing meals or breakfast may cause hypoglycemia. Low blood sugar also leads to blurry vision and a strange feeling (metallic taste) in the mouth. Give your son proper nutrition and ensure that he is taking adequate water and fluids. Sometimes, prolonged screen time or reading without breaks can cause eye strain, leading to blurry vision. Give rest between studies and avoid sitting on laptops for a duration. Get clinically examined by an Eye Specialist to detect any vision problems. He will be accordingly treated. Infections in the oral cavity can affect both vision and cause unusual sensations in the mouth. Take care of his oral hygiene. Get him clinically assessed in the ER to rule out any developing neurological problems. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K, General & Family Physician