Akinetopsia, also known as motion blindness, is a visual processing disorder in which a patient has difficulty perceiving objects in motion. Akinetopsia is derived from Greek: a for “not”, kine for “move”, and opsia for “see”. Akinetopsia can vary in its severity. It is the most commonly described by the patient as “frames in a movie reel” or “stop-action motion” or “person appears and disappears randomly”. Complete akinetopsia is rarely observed but most of these patients have difficulty perceiving some motion. These patients often can no longer rely on their vision and often train their hearing to help estimate distance and interact with other people.
There are multiple causes of akinetopsia, but because this is a visual processing disorder and not a vision disorder, all etiologies involve the brain. Causes can include traumatic brain injury, post-concussion syndrome, Alzheimer’s disease, and hallucinogen persistent perception disorder (HPPD), and medication adverse effect.
Akinetopsia is thought to be associated with damage to the V5 (MT) portion of the brain. Vision information is first received in the V1-2 visual association cortex, the visuospatial motion is then processed in the V5 (MT) area. When there is damage to the V5 (MT) area, akinetopsia can occur. Based on the involvement of V5 (MT) area, the problem can be localized to the ventral stream responsible for perception or “what”.
The diagnosis of akinetopsia is made clinically. There are no diagnostic tests or pathognomonic examination findings.
The clinical history is most important in the diagnosis of akinetopsia. Because of the very unique set of symptoms, suspicion for akinetopsia can be high based on history alone. Patients often have very specific complaints, which they may describe as seeing individual“frames in a movie reel” or “stop-action motion” or “like I’m in room with strobe lights”. Rarely, patients may complain of severe visual impairment. History can also help determine the underlying cause. Additional questions to ask the patient include history of head trauma, Alzheimer’s disease, recreational drug use and medications.
Physical exams are generally noncontributory and these patients often have full near and distant visual acuity and a structurally normal eye exam
Akinetopsia can be a difficult condition to manage. Management depends on the underlying cause. One may consider vestibular and visual rehabilitation and neuro-optometric fusional vergences dysfunction rehabilitation. Neuro-optometric fusional vergence dysfunction rehabilitation has not been studied in a randomized controlled trial, so its effectiveness and use remain controversial. There are currently no approved medications for the treatment of this condition.
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