Introduction: Upper eyelid weighting decreases lagophthalmos by improving blink dynamics. The effect of weighting on static eyelid position is less well understood. This study describes the effect of upper eyelid weighting on ipsilateral and contralateral upper eyelid position.
Methods: Patients with unilateral lagophthalmos who underwent upper eyelid weight implantation were included. Primary outcome measures were ipsilateral and contralateral margin to reflex distance 1 (MRD1), preoperatively and postoperatively. MRD1 symmetry was assessed as a secondary outcome measure. Weight mass was examined as a covariate of MRD1 change.
Results: 23 patients (16 female, 7 male) met inclusion criteria. After weighting, contralateral MRD1 increased from mean [SD] 2.91 [1.41] mm to 3.77 [1.75] mm (p < .05). Ipsilateral (weighted) MRD1 did not significantly change (2.64 [1.41] mm to 2.40 [1.18] mm, p = .11). Preoperatively, paretic and normal side MRD1 were not different (p = .52). Postoperatively, weighted and unweighted MRD1 were significantly different (p < .05). Weight mass was not a covariate of MRD1 change, neither ipsilateral nor contralateral (p = .76, p = .71, respectively). The proportion of patients with MRD1 asymmetry ≥ 1 mm preoperatively (12/23, 52.2%) did not change following surgery (17/23, 73.9%, p = .12).
Conclusion: Weight insertion led to contralateral eyelid elevation, a manifestation of Hering's law. Weight mass did not impact the magnitude of MRD1 change, and the proportion of patients with MRD1 asymmetry ≥ 1 mm did not change following surgery. These findings may guide surgeons in their preoperative planning and in counseling of patients.
Keywords: Hering’s; MRD1; lagophthalmos; upper eyelid.