One eye is swollen and the other is not, which may be due to physiological reasons, external reasons, or internal reasons: physiological reasons include visual fatigue, etc.; external reasons refer to eye infections, etc.; internal reasons include chronic diseases such as high blood pressure and diabetes. 1. Physiological reasons: excessive use of eyes, such as watching electronic products for a long time, leading to visual fatigue, there may be one side of the eye and one side of the eye is not swollen performance. 2. External causes: If the patient’s eyes are infected, such as conjunctivitis, keratitis, it will lead to one side of the eye and one side of the eye is not swollen, some patients have contact with some allergic substances, rubbing the eyes can also cause contact dermatitis, which will cause the above situation. 3. Intrinsic causes: some patients with systemic diseases such as hypertension, diabetes, kidney disease, etc., can also cause one eye to be swollen and one eye not swollen. In addition, some intracranial space-occupying lesions compressing the optic nerve can also occur. If one eye is swollen and the other is not, if it is not relieved after resting and accompanied by other uncomfortable symptoms, we should clarify the specific cause under the guidance of the doctor and actively treat it to avoid serious consequences.