Please the causation of Iris moving quickly from side to side - no stillness?

The person I met in the supermarket his Iris was constantly moving from side to side although he did not speak. James Gallway had the same when he played his Flute.

Please the causation of Iris moving quickly from side to side - no stillness?
Good answer owlwings - the cause of nystagmus is unknown - 1 theory is the brain is constantly searching for the area of highest visual acuity on the retina and is constantly scanning it. People with nystagmus generally have a reduced visual acuity (even if you take the nystagmus into account). Nystagmus is also split into beat-nystagmus and pendular nystagmus. Beat nystagmus is where the speed of the movement is greater in one direction than the other so the eye looks as if it is beating in one direction. Pendular nystagmus is where the eye moves back and forth (or up and down) equally in either direction. The condition is also more highly prevalent in albinos. Finally you can get torsional nystagmus where the eye rotates along the axis of the pupil - but this is very rare!
Reply:No links. No thumb's-up point. Report It

Reply:It's a tic and is caused by some kind of pathway in the brain having a little mix-up.
Reply:Nystagmus refers to rapid involuntary movements of the eyes that may be from side to side (horizontal nystagmus), up and down (vertical nystagmus) or rotary. Depending on the cause, these movements may be in both eyes or in just one eye. The term "dancing eyes" has been used in regional dialect to describe nystagmus.





The involuntary eye movements of nystagmus are caused by abnormal function in the areas of the brain that control eye movements. The exact nature of these disorders is poorly understood. Nystagmus may be either congenital (present at birth) or may be acquired (caused by disease or injury later in life).


Etc ...





I have also seen it in blind people.
Reply:This is an irritating phenomena !





When it happens the person ,is usually aware that their eye is" twiddling "---- and will rub their eyes.





It may also be over stimulation of mental processes


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illustrated by your example of James Galway , concentrating on his music .





often caused by extreme tiredness
Reply:thats nice
Reply:These are all good answers although not strictly speaking accurate. When the whole eye moves, the bit you notice is the iris, the coloured bit, and yes this is nystagmus. But it is possible for the iris to move on its own, this is called iridodonesis and occurs in certain rare conditions.