Eyelid movements in facial paralysis
P. A. Sibony, C. Evinger and K. A. Manning
Department of Ophthalmology, SUNY, Stony Brook 11794.
We studied the eyelid movements of six patients with unilateral, isolated,
facial paralysis using the magnetic search coil. The most significant
abnormality consisted of a reduction in the magnitude of the orbicularis
oculi contraction with slowing of the peak velocity of the closing phase of
the blink. The closing phase blink velocity, which normally increases
linearly as a function of amplitude (main sequence), in our patients
displayed a relationship characterized by a slow saturating power function
that fell off the main sequence. The contralateral normal lid in some cases
can show adaptive signs of hyperactivity during the closing phase of the
blink. Lid saccades showed a small but consistent decrease in amplitude and
velocity compared with the contralateral unaffected eyelid. Unlike the
closing phase of the blink, peak velocities of lid saccades stayed on the
main sequence. In this study, we discuss how the eyelid executes downward
lid saccades based purely on a passive mechanism.
