Akinetopsia

Akinetopsia (Greek: a for "without", kine for "to move" and opsia for "seeing"), also known as cerebral akinetopsia or motion blindness, is a neuropsychological disorder in which a patient cannot perceive motion in his or her visual field, despite being able to see stationary objects without issue. There are varying degrees of akinetopsia: from seeing motion as a cinema reel to an inability to discriminate any motion. There is currently no effective treatment or cure for akinetopsia.

Akinetopsia can be separated into two categories based on symptom severity and the amount the akinetopsia affects the patients quality of life

Inconspicuous akinetopsia is often described by seeing motion as a cinema reel or a multiple exposure photograph. This is the most common kind of akinetopsia and many patients consider the stroboscopic vision as a nuisance. The akinetopsia often occurs with visual trailing (palinopsia), with afterimages being left at each frame of the motion. It is caused by prescription drugs, hallucinogen persisting perception disorder (HPPD), and Persistent aura without infarction. The pathophysiology of akinetopsia palinopsia is not known, but it has been hypothesized to be due to inappropriate activation of physiological motion suppression mechanisms which are normally used to maintain visual stability during eye movements (e.g. saccadic suppression).

Gross akinetopsia is an extremely rare condition. Patients have profound motion blindness and struggle in performing the activities of daily living. Instead of seeing vision as a cinema reel, these patients have trouble perceiving gross motion. Most of what is known about this extremely rare condition was learned through the case study of one patient, LM. LM described pouring a cup of tea or coffee difficult "because the fluid appeared to be frozen, like a glacier". She did not know when to stop pouring, because she could not perceive the movement of the fluid rising. LM and other patients have also complained of having trouble following conversations, because lip movements and changing facial expressions were missed. LM stated she felt insecure when more than two people were walking around in a room: "people were suddenly here or there but I have not seen them moving". Movement is inferred by comparing the change in position of an object or person. LM and others have described crossing the street and driving cars to also be of great difficulty. LM started to train her hearing to estimate distance.

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