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macropsia
Macropsia (also known as megalopia) is a neurological condition affecting human visual perception, in which objects within an affected section of the visual field appear larger than normal, causing the person to feel smaller than they actually are. Macropsia, along with its opposite condition, micropsia, can be categorized under dysmetropsia. Macropsia is related to other conditions dealing with visual perception, such as aniseikonia and Alice in Wonderland Syndrome (AIWS, also known as Todd’s syndrome). Macropsia has a wide range of causes, from prescription and illicit drugs, to migraines and (rarely) complex partial epilepsy, and to different retinal conditions, such as epiretinal membrane.〔 Physiologically, retinal macropsia results from the compression of cones in the eye. It is the compression of receptor distribution that results in greater stimulation and thus a larger perceived image of an object.
==Signs and symptoms==
The most obvious symptom of macropsia is the presence of exceptionally enlarged objects throughout the visual field. For example, a young girl might see her sister’s books as the same size as her sister. Stemming from this symptom, someone with macropsia may feel undersized in relation to his or her surrounding environment. Patients with macropsia have also noted the cessation of auditory function prior to the onset of visual hallucination, indicating possible seizure either before or after the hallucination.〔 A buzzing sound in the ears has also been reported immediately before macropsia development. Some patients claim that symptoms may be eased if an attempt is made to physically touch the object which appears enormous in size.〔Macropsia. Schneck JM. Am J Psychiatry 121:1123-1124, May 1965 〕 It is important to note, however, that patients typically remain lucid and alert throughout episodes, being able to recount specific details. A person with macropsia may have no psychiatric conditions. Symptoms caused chemically by drugs such as cannabis, magic mushrooms, or cocaine tend to dissipate after the chemical compound has been excreted from the body. Those who acquire macropsia as a symptom of a virus usually experience complete recovery and restoration of normal vision.
Dysmetropsia in one eye, a case of aniseikonia, can present with symptoms such as headaches, asthenopia, reading difficulties, depth perception problems, or double vision.〔 The visual distortion can cause uncorrelated images to stimulate corresponding retinal regions simultaneously impairing fusion of the images. Without suppression of one of the images symptoms from mild poor stereopsis, binocular diplopia and intolerable rivalry can occur.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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