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Micropsia is a condition affecting human visual perception in which objects are perceived to be smaller than they actually are. Micropsia can be caused by optical factors (such as wearing glasses), by distortion of images in the eye (such as optically, via swelling of the cornea or from changes in the shape of the retina such as from retinal edema, macular degeneration, or central serous retinopathy), by changes in the brain (such as from traumatic brain injury, epilepsy, migraines, prescription drugs, and illicit drugs), and from psychological factors. Dissociative phenomena are linked with micropsia, which may be the result of brain-lateralization disturbance. Micropsia is also commonly reported when the eyes are fixating at (convergence), or focussing at (accommodation), a distance closer than that of the object in accord with Emmert's law. Specific types of micropsia include hemimicropsia, a form of micropsia that is localized to one half of the visual field and can be caused by brain lesions in one of the cerebral hemispheres. Related visual distortion conditions include macropsia, a less common condition with the reverse effect, and Alice in Wonderland Syndrome, a condition that has symptoms that can include both micropsia and macropsia. ==Definition== Micropsia is the most common visual distortion, or dysmetropsia. It is categorized as an illusion in the positive phenomena grouping of abnormal visual distortions. * Convergence-accommodative micropsia is a physiologic phenomenon in which an object appears smaller as it approaches the subject. * Psychogenic micropsia can present itself in individuals with certain psychiatric disorders.〔 * Retinal micropsia is characterized by an increase in the distance between retinal photoreceptors and is associated with decreased visual acuity.〔 * Cerebral micropsia is a rare form of micropsia that can arise in children with chronic migraines.〔 * Hemimicropsia is a type of cerebral micropsia〔 that occurs within one half of the visual field. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「micropsia」の詳細全文を読む スポンサード リンク
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