The pupil has a wide range of connections with various parts of the body, and its opening and closing are affected by a variety of factors, and its changes are clinically significant. When the pupil diameter is greater than 5mm and the dilation is persistent, the pupil is called dilated. If the pupil diameter is less than 2mm, it is called miosis. Sometimes through the pupil changes, can reflect some of the lesions in the body, and some of the lesions of the nervous system can also be based on the changes in the pupil, and make a localized diagnosis. 1, general examination: pay attention to the body temperature, fever, mostly for some infectious diseases such as cavernous sinus thrombosis, encephalitis, meningitis; eyeball protrusion can be seen in cavernous sinus thrombosis, intraorbital tumors, carotid cavernous sinus fistula; eye murmur is seen in the strength of the arterial cavernous sinus fistula; eye, neck, or brain trauma; the neck and pharynx, whether there are tumors, inflammation, enlarged lymph nodes. 2, pupil: is dilated or narrowed, is one side or bilateral, direct and indirect light reflex, the size of the eye crack, eyeball protrusion, congestion, eye movement function is affected, visual acuity and field of vision, diplopia, eye movement abnormalities and convergence abnormalities, etc., the same side of the face of the movement, sensation and sweating, the fundus of the eye has no vision of the papillary edema, congestion and atrophy. Other neurological localization signs such as limb paralysis, sensory abnormalities, and abnormalities of vegetative nerve function.