Swelling of one eye in children may be caused by inflammatory swelling, allergies, mosquito bites and other reasons. 1. Inflammatory swelling: Inflammation of the eyelids tends to cause eye swelling, such as blepharitis or dermatitis can stimulate localized swelling of the eyelids. Blepharitis attacks lead to swollen eyes, and usually there is also an increase in eye boogers. 2. Allergies: This may be due to the fact that the child is allergic and has not taken proper precautions. If one eye comes into contact with an allergen, the allergy will be triggered, so one eye will be swollen. 3. Mosquito and insect bites: Swelling of one eye can occur after being bitten by insects and ants due to lack of attention to protection in normal times. If a child has a swollen eye, it is recommended to go to the ophthalmologist immediately to find out the cause of the swelling and cooperate with the doctor for appropriate treatment.