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Tunnel vision (also known as Kalnienk vision) is the loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision.〔(Medical terms )〕 == Causes == Tunnel vision can be caused by: * Glaucoma, a disease of the eye. * Retinitis pigmentosa, a disease of the eye. * Blood loss (hypovolemia) * Alcohol consumption.〔(Effects of Alcohol on Vision )〕 In addition, the vision becomes blurred or double since eye muscles lose their precision causing them to be unable to focus on the same object. * Sustained (1 second or more) high accelerations.〔(Web Archive: Virtual Naval Hospital )〕 Typically, flying an airplane with a centripetal acceleration of up to or over 39 m/s2 (4gs) with the head towards the center of curvature, common in aerobatic or fighter pilots. In these cases, tunnel vision and greyout may proceed to a ''g''-force induced Loss Of Consciousness (''g''-LOC). * Hallucinogenic drugs, in particular the dissociatives. * Extreme fear or distress, most often in the context of a panic attack. * Excitement or extreme pleasure such as on a roller-coaster, causing a surge of adrenaline in the body. * During periods of high adrenaline production, such as an intense physical fight. * Altitude sickness, hypoxia in passenger aircraft〔(Web Archive: Aircraft air quality )〕 * Exposure to oxygen at a partial pressure above 1.5-2 atmospheres, producing central nervous system oxygen toxicity, called narcosis.〔(Web Archive: Virtual Naval Hospital, Oxygen Toxity )〕 Other symptoms can include dizziness, nausea, blindness, fatigue, anxiety, confusion and lack of coordination. * Pituitary tumours (or other brain tumours that compress the optic chiasm) * Prolonged exposure to air contaminated with heated hydraulic fluids and oils, as can sometimes happen in passenger aircraft.〔(Web Archive: Aircraft air quality )〕 * Severe cataracts, causing a removal of most of the field of vision * During the aura phase of a migraine * Intense anger, due to the body being rapidly flooded with adrenaline and oxygen * A bite from a Black Mamba and other snakes with the same strength venom. * Mercury poisoning (especially Methylmercury) * Sleep Deprivation When combined with piloting an aircraft, driving, crossing roads or operating heavy machinery, the consequences can be fatal. 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「tunnel vision」の詳細全文を読む スポンサード リンク
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