Ocular flutter refers to intermittent rapid saccadic eye movements around the point of fixation. The rapid movements occur in a sequence without the usual intersaccadic pause.
- ocular flutter is clinically characterized by intermittent bursts of conjugate, horizontal saccades without an intersaccadic interval
- amplitude of the saccades varies and may be so small that the saccades can only be observed by means of an ophthamoscope or slit-lamp.
- frequency tends to be 10-15 Hz, though it increases as the saccadic amplitude decreases
- patients often complain of oscillopsia (visual disturbance in which objects in the visual field appear to oscillate)
Ocular flutter differs from ocular dysmetria because in dysmetria an initial inaccurate eye movement is corrected after a normal intersaccadic pause by a corrective saccade.
Ocular flutter is closely related to opsoclonus, where saccades are multidirectional
- the two conditions have the same localizing value and differential diagnosis
- most common aetiologies are paraneoplastic syndrome, brainstem encephalitis, metabolic-toxic disturbance, and idiopathic.(1)
- in children, 50% of cases prove to be a paraneoplastic manifestation of neuroblastoman (2)
- in adults, paraneoplastic causes include malignancies, such as small cell lung cancer (SCLC) and breast cancer (3)
Reference:
- Leigh RJ, Zee DS. The Neurology of Eye Movements. 4th ed. New York: Oxford University Press; 2006. Diagnosis of nystagmus and saccadic intrusion; pp. 475-558
- Liu GT, Volpe NJ, Galetta SL. Neuro-Ophthalmology: Diagnosis and Management. Philadelphia: Saunders; 2010. Nystagmus and nystagmoid eye movements; pp. 587–610.
- Luque FA, Furneaux HM, Ferziger R, et al. Anti-Ri: an antibody associated with paraneoplastic opsoclonus and breast cancer. Ann Neurol. 1991;29:241-51 (3)