The sudden onset of drooping eyelids requires vigilance for diseases such as myasthenia gravis and oculopharyngeal muscular dystrophy. There are many causes of drooping eyelids, such as aging, not necessarily due to disease. 1. Ageing: As we age, loose and sagging skin is normal and is a form of skin aging that can lead to drooping eyelids. 2. Myasthenia gravis: Myasthenia gravis is a disease caused by dysfunction of transmission at the nerve-muscle junction, which is mainly related to disorders of the body’s immune system, and the causes of the disease include environmental factors, infectious factors, and medication factors, etc. The patients may have the symptoms of ptosis, which is manifested as drooping eyelids. 3. Oculopharyngeal myotonic dystrophy: Oculopharyngeal myotonic dystrophy is a type of myotonic dystrophy, which is usually caused by genetic factors, belonging to autosomal dominant or invisible inheritance, patients will have symptoms of drooping eyelids and progressive paralysis of extraocular muscles. If the eyelid ptosis occurs suddenly, it is recommended that the patient consult a doctor in time for relevant examinations and follow the doctor’s instructions for treatment.