Frontalis Muscle Contraction and the Role of Visual Deprivation and Eyelid Proprioception

PURPOSE: To determine if frontalis muscle contraction can be induced by manipulating visual and eyelid proprioceptive inputs through simulating visual deprivation and ptosis. METHODS: Volunteers without prior eyelid or forehead pathologic study were recruited for this nonrandomized, prospective study. Baseline and study phase brow positions were documented. The first phase was to simulate visual deprivation and the second to simulate ptosis. The dominant eye was used for each phase. As a proxy to simulate visual field deprivation, a black contact lens was placed on the eye, which reduced vision to light perception. As a proxy to simulate ptosis, an external eyelid weight was placed on the upper eyelid. Brow position ratios were calculated at various points along the brow and statistical analysis was performed. RESULTS: Fifteen subjects participated. The average brow position ratio was 1.00 ± 0.08 for the visual deprivation group, which was not different from baseline (p = 0.86). The average brow position ratio for the external eyelid weight group was 1.13 ± 0.07, which was statistically significant compared with baseline and the visual deprivation group (p < 0.001). CONCLUSIONS: Inducing visual deprivation with a black contact lens does not lead to a change in brow position. However, placing an external eyelid weight does lead brow elevation, with an average increase of 13% from baseline. This suggests a likely role for proprioceptive or sensory inputs in frontalis muscle contraction in the setting of eyelid ptosis.