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Disorders of the visual system can lead to dizziness, vertigo, and feelings of instability. Vertigo is not associated with illusory self-motion as it does not typically make one feel as though they are moving; however, in a subclass of vertigo known as subjective vertigo one does experience their own motion.
Lightheadedness is a common and typically unpleasant sensation of dizziness [1] or a feeling that one may faint. The sensation of lightheadedness can be short-lived, prolonged, or, rarely, recurring. In addition to dizziness, the individual may feel as though their head is weightless.
Tullio phenomenon, sound-induced vertigo, dizziness, nausea or eye movement was first described in 1929 by the Italian biologist Prof. Pietro Tullio.(1881–1941) [1] [2] During his experiments on pigeons, Tullio discovered that by drilling tiny holes in the semicircular canals of his subjects, he could subsequently cause them balance problems when exposed to sound.
There is also the pseudo-Coriolis effect (also referred to as the optokinetic pseudo-Coriolis effect), which takes place when there is no physical circular movement, only visual. [ 8 ] [ 9 ] Perceptually it feels the same as the Coriolis effect, being perceived as self motion inducing the same kind of nausea and often the cause of motion sickness.
Dizziness affects approximately 20–40% of people at some point in time, while about 7.5–10% have vertigo. [3] About 5% have vertigo in a given year. [10] It becomes more common with age and affects women two to three times more often than men. [10] Vertigo accounts for about 2–3% of emergency department visits in the developed world. [10]
Flicker vertigo, sometimes called the Bucha effect, is "an imbalance in brain-cell activity caused by exposure to low-frequency flickering (or flashing) of a relatively bright light." [ 1 ] It is a disorientation -, vertigo -, and nausea -inducing effect of a strobe light flashing at 1 Hz to 20 Hz, approximately the frequency of human brainwaves .
Hyperphantasia is the condition of having extremely vivid mental imagery. [1] It is the opposite condition to aphantasia, where mental visual imagery is not present. [2] [3] The experience of hyperphantasia is more common than aphantasia [4] [5] and has been described as being "as vivid as real seeing". [4]
Oscillopsia is a visual disturbance in which objects in the visual field appear to oscillate. The severity of the effect may range from a mild blurring to rapid and periodic jumping. [ 1 ] Oscillopsia is an incapacitating condition experienced by many patients with neurological disorders . [ 2 ]