Paralytic strabismus is a type of strabismus that is caused by paralysis of one or more extraocular muscles due to organic lesions of the extraocular muscles or their innervated nerves. The paralysis of the extraocular muscles leads to the inability to work normally. The lesion is characterized by the deviation of the affected eye in the opposite direction of the action of the paralyzed eye muscles, the impaired movement of the affected eye in the direction of the action of the paralyzed eye muscles, and the greater angle of strabismus with the affected eye than with the healthy eye. The clinical manifestations of paralytic strabismus include diplopia, ocular vertigo, and compensatory head position. These symptoms directly affect the patient’s life and work, which is what patients and their families should pay attention to. Once these behaviors and symptoms are detected, they should be examined and treated in a professional hospital as soon as possible to avoid delaying the diagnosis and treatment. Diplopia is a conscious symptom that must appear in the early stage of paralytic strabismus. After one of the extraocular muscles is paralyzed, the affected eye becomes oblique, and both eyes cannot look at the same target at the same time, and the original monocular function and normal retinal correspondence are destroyed. Ocular vertigo Because patients with paralytic strabismus are unable to adapt to the abnormal situation in which the real and virtual images interfere with the visual center of the brain at the beginning of the disease, they are often accompanied by dizziness, nausea and vomiting, which are called ocular vertigo. In order to avoid double vision or to reduce the distance between the real image and the false image in double vision, the patient often adopts a certain head tilted gaze method to compensate for the function of the paralyzed eye muscles. This abnormal head position caused by ocular muscle paralysis is called compensatory head position. Since these symptoms are caused by the deviation of eye position due to extraocular muscle paralysis, symptoms such as diplopia and vertigo, nausea and vomiting will disappear immediately after covering the affected eye. This is also a way to self-diagnose strabismus.