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Nystagmus. Nystagmus is a condition of involuntary (or voluntary, in some cases) [1] eye movement. [2] People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. [3] In normal eyesight, while the head rotates about an axis, distant visual images are sustained by ...
Horizontal optokinetic nystagmus. The optokinetic reflex ( OKR ), also referred to as the optokinetic response, or optokinetic nystagmus (OKN), is a compensatory reflex that supports visual image stabilization. [ 1] The purpose of OKR is to prevent image blur on the retina that would otherwise occur when an animal moves its head or navigates ...
Positional alcohol nystagmus. Positional alcohol nystagmus (PAN) is nystagmus (visible jerkiness in eye movement) produced when the head is placed in a sideways position. PAN occurs when the specific gravity of the membrane space of the semicircular canals in the ear differs from the specific gravity of the fluid in the canals because of the ...
Benign paroxysmal positional vertigo ( BPPV) is a disorder arising from a problem in the inner ear. [ 3] Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head. [ 1] This can occur with turning in bed or changing position. [ 3]
Episodic ataxia ( EA) is an autosomal dominant disorder characterized by sporadic bouts of ataxia (severe discoordination) with or without myokymia (continuous muscle movement). There are seven types recognized but the majority are due to two recognized entities. [ 1] Ataxia can be provoked by psychological stress or startle, or heavy exertion ...
Specialty. Neurology. Intention tremor is a dyskinetic disorder characterized by a broad, coarse, and low-frequency (below 5 Hz) tremor evident during deliberate and visually-guided movement (hence the name intention tremor). An intention tremor is usually perpendicular to the direction of movement. When experiencing an intention tremor, one ...
Vestibulocerebellar syndrome. Vestibulocerebellar syndrome, also known as vestibulocerebellar ataxia, is a progressive neurological disorder that causes a variety of medical problems. Initially symptoms present as periodic attacks of abnormal eye movements but may intensify to longer-lasting motor incapacity. The disorder has been localized to ...
Albinism is a congenital condition characterized in humans by the partial or complete absence of pigment in the skin, hair and eyes. Albinism is associated with a number of vision defects, such as photophobia, nystagmus, and amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers.