Purpose: To measure the effect of müllerectomy from posterior approach on the amplitudes of spontaneous blinking and downward eyelid saccades.
Methods: Spontaneous blinks and downward upper eyelid saccadic movements of 16 patients (23 eyelids) with Graves orbitopathy were measured before and after müllerectomy from posterior approach. A new video system was used to continuously register the blinking activity while subjects viewed a commercial movie for 5 minutes. Downward eyelid saccades (30° of downgaze) were also measured with the video system.
Results: Müllerectomy had no effect on the amplitude of the blink. However, as the eyelid margins were significantly lowered by the surgery, the amplitude of the blink movements relative to the pupil center increased substantially. The number of movements occluding the pupil center increased from 0% to 13%. Due to the increased efficiency of blinking, the blink rate decreased. Surgery induced a mean increase of 1.1 mm of downward saccades.
Conclusions: The effects of müllerectomy on the blinks are indirect and related to correction of eyelid retraction. The relative amplitude of blink movements increases and blink rate decreases. Müllerectomy does affect the downward eyelid saccades increasing the ability of the upper eyelid to relax on downgaze.