Ocular Dysmetria

    • Binocular dampening oscillations triggered by refixational eye movements
    • Extreme form is called “macrosaccadic oscillations”
    • This is the ocular equivalent of ataxia
    • Common cause: cerebellar system dysfunction
    • Core clinical features
      • Eyes overshoot the fixation target, oscillate briefly around it, finally settling on it
      • Extremity, gait, and/or speech ataxia
    • Possible accompanying clinical features
      • Refixational eye movements may cause blurred vision until the eyes settle on the target
    • Imaging features
      • Lesions of the brainstem or cerebellum
    • Ocular flutter or opsoclonus
    • Square wave jerks
    • Volitional flutter
    • Infantile motor or sensory nystagmus
    • Note whether the oscillations interrupt fixation, which would suggest square wave jerks, or whether they occur only when the patient makes refixational movements, which would suggest ocular dysmetria
    • Instruct the patient to direct gaze first at an eccentrically-positioned fixation light, then at a centrically-positioned fixation light, and note whether the eyes overshoot the viewed target, especially when the eyes are directed toward the centrically-positioned fixation light
    • Tip: ocular dysmetria is hard to distinguish from ocular flutter
    • Trap: ocular dysmetria may also occur when the patient’s eyes appear still, because even invisibly small refixations can trigger it
    • Look for extremity, gait, and speech ataxia, which are especially common accompaniments of ocular dysmetria, but do not exclude other causes of ocular oscillations
    • Depends on the underlying condition

    Nystagmus-like Oscillations

    Overview Video Convergence Retraction Superior Oblique Myokymia Square Wave Jerks Saccades of Inattention Ocular Flutter and Opsoclonus Volitional Flutter Ocular Dysmetria Ocular Bobbing Ping Pong Gaze Oscillations of Internuclear Ophthalmoplegia Epileptic Oscillations