Amsler grid as it might appear to someone with<unk>  as a result of age-related macular degeneration. EEG testing can diagnose patients with medial temporal lobe epilepsy. Epileptiform abnormalities including spikes and sharp waves in the medial temporal lobe of the brain can diagnose this condition, which can in turn be the cause of an epileptic patient's<unk> . The Amsler grid test can be used to diagnose macular degeneration. For this test, patients are asked to look at a grid, and distortions or blank spots in the patient's central field of vision can be detected. A positive diagnosis of macular degeneration may account for a patient's<unk> . A controlled size comparison task can be employed to evaluate objectively whether a person is experiencing hemimicropsia. For each trial, a pair of horizontally aligned circles is presented on a computer screen, and the person being tested is asked to decide which circle is larger. After a set of trials, the overall pattern of responses should display a normal distance effect where the more similar the two circles, the higher the number of errors. This test is able to effectively diagnose<unk>  and confirm which hemisphere is being distorted. Due to the large range of causes that lead to<unk> , diagnosis varies among cases. Computed tomography (CT) and magnetic resonance imaging (MRI) may find lesions and hypodense areas in the temporal and occipital lobes. MRI and CT techniques are able to rule out lesions as the cause for<unk> , but are not sufficient to diagnose the most common causes. Definition<unk>  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<unk>  is a physiologic phenomenon in which an object appears smaller as it approaches the subject. * Psychogenic<unk>  can present itself in individuals with certain psychiatric disorders. * Retinal<unk>  is characterized by an increase in the distance between retinal photoreceptors and is associated with decreased visual acuity. * Cerebral<unk>  is a rare form of<unk>  that can arise in children with chronic migraines. * Hemimicropsia is a type of cerebral<unk>  that occurs within one half of the visual field. Differential diagnosis Of all of the visual distortions,<unk>  has the largest variety of causes. Migraines<unk>  can occur during the aura phase of a migraine attack, a phase that often precedes the onset of a headache and is commonly characterized by visual disturbances.<unk> , along with hemianopsia, quadrantopsia, scotoma, phosphene, teicopsia, metamorphopsia,<unk> , teleopsia, diplopia, dischromatopsia, and hallucination disturbances, is a type of aura that occurs immediately before or during the onset of a migraine headache. The symptom usually occurs less than thirty minutes before the migraine headache begins and lasts for five to twenty minutes. Only 10-20% of children with migraine headaches experience auras. Visual auras such as<unk>  are most common in children with migraines. Seizures The most frequent neurological origin of<unk>  is a result of temporal lobe seizures. These seizures affect the entire visual field of the patient. More rarely,<unk>  can be part of purely visual seizures. This in turn only affects one half of the visual field and is accompanied by other cerebral visual disturbances. The most common cause of seizures which produce perceptual disturbances such as<unk>  and<unk>  is medial temporal lobe epilepsy in which the seizures originate in the amygdala-hippocampus complex.<unk>  often occurs as an aura signalling a seizure in patients with medial temporal lobe epilepsy. Most auras last for a very short period, ranging from a few seconds to a few minutes. Drug use<unk>  can result from the action of mescaline and other hallucinogenic drugs. Although drug-induced changes in perception usually subside as the chemical leaves the body, long-term cocaine use can result in the chronic residual effect of<unk> .<unk>  can be a symptom of Hallucinogen Persisting Perception Disorder, or HPPD, in which a person can experience hallucinogenic flashbacks long after ingesting a hallucinogen. A majority of these flashbacks are visual distortions which include<unk> , and 15-80% of hallucinogen users may experience these flashbacks.<unk>  can also be a rare side effect of zolpidem, a prescription medication used to temporarily treat insomnia. Psychological factors Psychiatric patients may experience<unk>  in an attempt to distance themselves from situations involving conflict.<unk>  may also be a symptom of psychological conditions in which patients visualize people as small objects as a way to control others in response to their insecurities and feelings of weakness. In some adults who experienced loneliness as children,<unk>  may arise as a mirror of prior feelings of separation from people and objects. Epstein-Barr virus infection<unk>  can be caused by swelling of the cornea due to infection by the Epstein-Barr virus (EBV) and can therefore present as an initial symptom of EBV mononucleosis, a disease caused by Epstein-Barr virus infection. Retinal edema MRI image of a brain tumor occupying the left temporal and parieto-occipital regions of the brain.|alt=Non-contrast magnetic resonance imaging showing hyper-intense lesion involving the left temporal and parieto-occipital regions. The tumor is crossing the midline to the right parietal region.Micropsia can result from retinal edema causing a dislocation of the receptor cells. Photoreceptor misalignment seems to occur following the surgical re-attachment for macula-off rhegmatogenous retinal detachment. After surgery, patients may experience<unk>  as a result of larger photoreceptor separation by edematous fluid. Macular degeneration Macular degeneration typically produces<unk>  due to the swelling or bulging of the macula, an oval-shaped yellow spot near the center of the retina in the human eye. The main factors leading to this disease are age, smoking, heredity, and obesity. Some studies show that consuming spinach or collard greens five times a week cuts the risk of macular degeneration by 43%. Central serous chorioretinopathy CSCR is a disease in which a serous detachment of the neurosensory retina occurs over an area of leakage from the choriocapillaris through the retinal pigment epithelium (RPE). The most common symptoms that result from the disease are a deterioration of visual acuity and<unk> . Brain lesions<unk>  is sometimes seen in individuals with brain infarctions. The damaged side of the brain conveys size information that contradicts the size information conveyed by the other side of the brain. This causes a contradiction to arise between the true perception of an object's size and the smaller perception of the object, and<unk>  bias ultimately causes the individual to experience<unk> . Lesions affecting other parts of the extracerebral visual pathways can also cause<unk> .
Micropsia
Palinopsia
Photopsia
Dysmorphopsia
Pelopsia
Cerebral polyopia
Akinetopsia
Ocular dysmetria