One eye suddenly turns into double eyelids, which is mostly caused by visual fatigue, hereditary reasons, and may also be caused by blepharitis, allergic dermatitis and so on. If people usually do not have a good rest and have too much mental stress, it will lead to excessive eye fatigue and temporary relaxation of eyelid skin, which manifests as a transient double eyelid. If both parents have double eyelids, their children have single eyelids in early childhood, but with age, double eyelids can also appear. If the patient has inflammation of both eyelids, such as blepharitis, allergic dermatitis, etc., under the stimulation of inflammation, the patient may have eyelid swelling, congestion, and may have the manifestation of single eyelid to double eyelids. Patients with blepharitis can be treated with erythromycin ophthalmic ointment as prescribed by the doctor, and after the formation of eyelid abscess, surgical incision and drainage of pus is feasible to promote the subsidence of abscess. It is recommended that patients with significant eyelid discomfort should seek prompt medical attention to evaluate their condition and follow the doctor’s instructions for treatment.