Abstract
Purpose: :
To characterize the eye movement abnormalities associated with Crouzon syndrome
Methods: :
We measured gaze–dependent binocular alignment and eye movements using binocular infrared video–oculography in 6 subjects with Crouzon syndrome. We also assessed the relative position of the extraocular rectus muscle pulleys using high resolution CT imaging.
Results: :
Two subjects had normal eye alignment in primary and vertical gazes, three subjects had a V–pattern exotropia and one subject had a V–pattern esotropia. Gaze holding in the light was stable except in one subject with an Arnold–Chiari malformation. Smooth pursuit gains to target velocities of 10, 20 and 30 deg/sec ranged from 0.5 to 1.0, 0.5 to 0.8 and 0.3 to 0.7 respectively, and catch–up saccades were increased in frequency. Saccades were highly variable with averaged gains of 0.83 in upgaze, 0.93 in downgaze, 0.80 in gaze right and 0.82 in gaze left. High contrast square wave gratings drifted at velocities of 15, 30 and 45 deg/sec elicited appropriately directed optokinetic responses uniformly having reduced slow–phase gains. Abnormal intrusions of vertical dysconjugacy were uniformly observed during vertical saccades, horizontal smooth pursuit and angular vestibulo–ocular reflex. High resolution CT consistently demonstrated excyclorotation of the rectus muscle pulleys with vertical offset of the horizontal rectus muscles and horizontal offset of vertical rectus muscles.
Conclusions: :
Excyclorotation of the rectus muscle pulleys produces an imbalance of dynamic muscle forces due to the loss of coplanarity in the pulling directions of muscle agonists that reduces the accuracy of conjugate eye movements.
Keywords: eye movements • eye movements: conjugate • extraocular muscles: structure