The patient sees objects much smaller than they are. It can be a type of perceptual syndrome, or illusion, and is mostly seen in ophthalmic vascular disorders or as an ocular symptom of central nervous system disorders. What is the differential diagnosis of reduced visual acuity? The following are the differential diagnoses of diminished visual acuity. 1. Temporal lobe epilepsy: (temporallobeepilepsy) is a common clinical condition in which the visual objects become larger, smaller, and distorted. This perceptual change usually arises during a seizure of the disease, or it may be the precursor of a single seizure. The patient feels that the object he/she is looking at is sometimes larger, sometimes smaller, sometimes farther away, sometimes closer, and in more complex cases, there are visual distortions, etc. These manifestations often affect the patient’s behavior. 2. Schizophrenia: Dissociation of reality can occur, and the change is a manifestation of spatial perception syndrome. Patients do not feel any change in the attributes of external things, but the impression of external things is not vivid, not obvious, often blurred, such as across the curtain, nebulous, and lacking a sense of reality. 3, epidemic encephalitis B (epidemicencephalitisB): in its acute phase, high fever can louver 40 ℃ or more, there can be varying degrees of impaired consciousness and even coma, producing psychiatric symptoms, there can be perceptual syndrome such as visual objects become larger, visual objects become smaller, visual objects deformation. With the improvement of consciousness disorder, perceptual disorder can disappear quickly. 4.Cocaine and cynurenine intoxication: The patient’s cortical receptor cells and conduction fibers become metabolically impaired, and perceptual syndrome such as distortion and enlargement of visual objects may appear.