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Avery H Weiss, James O Phillips, Eye movements,strabismus and amblyopia; Crouzon Syndrome: Relationship of Eye Movements to Pattern Strabismus. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2657.
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© ARVO (1962-2015); The Authors (2016-present)
To characterize the conjugate eye movements of patients with Crouzon syndrome.
Ten children with Crouzon syndrome were studied, five had a pattern strabismus (V-pattern exotropia or A-pattern esotropia); the remaining five had normal eye alignment in primary gaze. We recorded gaze holding and conjugate eye movements in response to stimuli designed to elicit smooth pursuit, saccades, optokinetic nystagmus (OKN), vestibular-ocular reflex (VOR) and vergence using binocular or monocular video-oculography.
Gaze holding was stable in 8 of 10 patients. Two patients with an Arnold Chiari malformation had nystagmus, one had downbeat nystagmus and one had a left-beating jerk nystagmus. Smooth pursuit gains at peak stimulus velocities of 10, 20 and 30 deg/sec were and 0.91±0.13, 0.83±0.07 and 0.77±0.13 and 0.54±0.22, 0.52±0.13 and 0.43±0.12 in patients without and with strabismus, respectively. Saccadic gains in response to horizontal steps of 5 to 20 deg were on average 0.88±0.13 and 0.84±0.10 in patients without and with strabismus. Horizontal OKN gain to vertical gratings drifted at velocities of 15, 30 and 45 deg/sec were 0.68±0.13, 0.56±0.13 and 0.53±0.14 and 0.38±0.16, 0.26±0.06 and 0.15±0.09 in patients without and with strabismus respectively. Vestibular ocular reflex gains across rotation frequencies (0.16, 0.32 and 0.64Hz) were normal in patients without or with pattern strabismus.
Patients with Crouzon syndrome had subnormal gains for horizontal smooth pursuit and OKN but normal gains for saccades and horizontal VOR. This finding indicates that these patients have a selective deficit in tracking the trajectory of a target drifting sinusoidally or at constant velocity. We propose that this deficit in tracking horizontal motion is due to variable shifts in horizontal and vertical eye alignment, especially at the turnaround points, imposed by extorsion of the globe and “over-elevation in adduction”.
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