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Akinetopsia
Published in Alexander R. Toftness, Incredible Consequences of Brain Injury, 2023
Akinetopsia is an extremely rare disorder in which a person loses the ability to perceive movement. This loss of movement perception occurs in all three dimensions: up-down, left-right, and back-forth. Generally, this loss of movement does not depend on whether the person is looking directly at the object or if they are looking somewhere else when the object moves in their peripheral vision. Instead of objects looking like they are smoothly moving from one position to another, unmoving objects may be perceived as jumping suddenly from place to place like freeze-frames in a movie (Sakurai et al., 2013). This disorder is probably best illustrated by, perhaps ironically, a video, which is why I have created one over on my ARTexplains Science and History YouTube channel (Toftness, 2018).
Cortical Visual Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Defects that can be associated with akinetopsia include hemifield defects, problems on other visuospatial tests and poor stereopsis (352). Given the rarity of these cases, little is known about their prognosis. Some have improved over the first year (369, 370). In monkeys, recovery varies with the extent of damage (371).
How to master MCQs
Published in Chung Nen Chua, Li Wern Voon, Siddhartha Goel, Ophthalmology Fact Fixer, 2017
GerstmaniYs syndrome results from a lesion in the dominant parietal lobe. It is characterised by acalculia, agraphia, finger agnosia and left-right confusion. Prosopagnosia is an inability to recognise familiar faces and usually results from bilateral occipitotemporal involvement. Achromatopsia is abnormal colour discrimination and can arise from bilateral parietal or occipital lobe abnormalities. Akinetopsia implies insensitivity to motion and can result from a lesion in the middle temporal gyrus. Anton's syndrome occurs in blind patients who deny they are blind. It is seen in bilateral occipital lesions.
Current practice and challenges in screening for visual perception deficits after stroke: a qualitative study
Published in Disability and Rehabilitation, 2022
Kathleen Vancleef, Michael J. Colwell, Olivia Hewitt, Nele Demeyere
Visual perception is the dynamic process of perceiving the environment through sensory inputs and translating the sensory input into meaningful concepts associated with visual knowledge of the environment [1]. Visual perception problems are therefore distinct from sensory visual impairments such as reduced visual acuity, visual field and eye movements [2]. Where sensory visual impairments result from damage to the eye or early visual pathways from the eye to the primary visual cortex, visual perception deficits are attributed to impaired function in later visual processing areas in the occipital, parietal and temporal cortex [3]. Examples of visual perceptual deficits include apperceptive and associative agnosia (object recognition difficulties), prosopagnosia (face recognition difficulties), akinetopsia (difficulties in perceiving motion), achromatopsia (difficulties in perceiving colour), problems in visual memory (remembering what you have seen before), and in visuospatial abilities (e.g., judging distances or spatial relations between objects) [3]. Visual inattention or hemispatial neglect is sometimes considered to be part of visual perception [1,4], though neuropsychology research attributes this to an attentional deficit [5]. In particular, the presence of preserved perception when attention is stretched to focus on the stimuli, the existence of cross-modal neglect and manipulations of stimulus density on the extent of neglect support the classification of hemispatial neglect as a disorder of attention [6,7].
Perioperative Vision Loss after Non-Ocular Surgery
Published in Seminars in Ophthalmology, 2018
Bart Chwalisz, Aubrey L. Gilbert, John W. Gittinger
CVL is characterized by loss of vision with normal pupillary function and a normal funduscopic appearance. Central acuity is generally preserved unless bilateral damage has occurred. Occasionally, patients may be unaware of and deny cortical blindness (Anton syndrome). Complex and unusual higher-order disturbances of visual function may occur if the involved area is outside of the primary visual cortex, such as problems with recognition of color (central achromatopsia) and movement (akinetopsia), visual agnosia, and contralateral neglect. Additional neurological findings and decreased level of arousal may be present. CVL may be caused by embolic infarction of the posterior visual pathways and/or visual areas of the occipito-parietal cortex. Additional mechanisms of injury include watershed infarction, posterior reversible encephalopathy syndrome (PRES), and potentially various other uncommon pathologies such as cerebral hemorrhage and cortical venous sinus thrombosis.
Impact of visual impairment following stroke (IVIS study): a prospective clinical profile of central and peripheral visual deficits, eye movement abnormalities and visual perceptual deficits
Published in Disability and Rehabilitation, 2022
Fiona J. Rowe, Lauren R. Hepworth, Claire Howard, Kerry L. Hanna, Jim Currie
Disorders of visual perception occur frequently following stroke with the most commonly recognised disorder being visual inattention/neglect [1,15]. Visual perception disorders can include impaired recognition (visual agnosia) of objects (object agnosia), faces (prosopagnosia) and colour (achromatopsia), impaired depth, impaired constancy (e.g., micropsia, macropsia), sight impairment recognition (e.g., Anton’s syndrome, Riddoch phenomenon), and impaired motion or spatial detection (e.g., akinetopsia, polyopia, visual perseveration, palinopsia) [1,15,16]. A further disorder, particularly following sight impairment, is visual hallucinations which may be formed or unformed and including Charles Bonnet syndrome [15,17].