The patient sees object images as much smaller than they are. It can be a type of perceptual syndrome, or delusion, and is mostly seen as an ocular symptom of ocular vascular disorders or central nervous system disorders. The patient has a subjective feeling of seeing things smaller. Ophthalmologic examination and cranial examination are needed to identify. The following is how to diagnose the smallness of vision. 1, schizophrenia: there can be a dissolution of reality, change belongs to a form of spatial perception syndrome disorder. Patients feel no change in the attributes of external things, but the impression of external things is not vivid, not obvious, often vague, such as through the curtain, indistinct, lack of reality. 2.Temporal lobe epilepsy: (temporallobeepilepsy) clinically common visual objects become larger, visual objects become smaller, visual objects deformed. This kind of perceptual change usually occurs in the seizure of the disease, or may be the aura of a seizure, the patient feels that the objects viewed by the patient sometimes become larger, sometimes smaller, sometimes far away, sometimes close to, and more complex when there is a distortion of the visual object, and so on. The above manifestations often affect the patient’s behavior. 3.Cocaine, senecionine poisoning: patients with cortical sensory cells and conduction fibers appear metabolic disorders, stay appearing visual deformation, visual objects become larger and other perceptual disorders. 4, epidemic encephalitis B (epidemicencephalitisB): in its acute stage, high fever can blinds 40 ℃ or more, there can be varying degrees of consciousness disorder and even coma, produce mental symptoms, can appear in the eyesight becomes large, eyesight becomes small, eyesight deformation and other perceptual syndrome disorder. With the improvement of the consciousness disorder, the perception disorder can disappear quickly.