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iridodonesis

n. The vibration or agitated motion of the iris with eye movement.

Wikipedia
Iridodonesis

Iridodonesis is the vibration or agitated motion of the iris with eye movement. This may be caused by lens subluxation, the incomplete or partial dislocation of the lens; or by aphakia, the absence of a lens. The term originated from irido- + doneo (, to shake to and fro).