Swollen and itchy eyes may be caused by overuse of eyes, conjunctivitis, keratitis and other reasons. 1. Excessive eye use: Staying up late, using electronic products for a long time, reading in a dark environment and other bad eye habits may lead to excessive eye fatigue, resulting in poor blood circulation in the eyes, resulting in itchy and swollen eyes. 2. Conjunctivitis: Conjunctivitis can be caused by bacterial, viral and other microbial infections, but also due to the spread of inflammation in neighboring tissues. The common clinical symptoms are itchy eyes, photophobia, edema, pain and so on. 3. Keratitis: Keratitis can be caused by infection, autoimmune disease, spread of neighboring tissues, etc. The inflammation stimulation is manifested as eye pain, photophobia, itching, swelling and other symptoms, which can last until the inflammation disappears. Swollen and itchy eyes can also be seen in allergies and other causes, it is recommended that patients seek medical attention in a timely manner, under the diagnosis and guidance of a professional doctor for treatment.