Abstract
Purpose:
Lower blepharoplasty is widely performed esthetic surgery that occasionally results in strabismus. The inferior oblique (IO) pulley is elastically coupled to the actively moving inferior rectus (IR) pulley. We hypothesized that the lower blepharoplasty could change the IO path, which might contribute to vertical strabismus following blepharoplasty. This study investigated, using high-resolution magnetic resonance imaging (MRI), the position of IO and capsulopalpebral fascia (CPF) relative the adjacent structures in normal subjects and subjects with vertical strabismus following the lower blepharoplasty.
Methods:
High resolution MRI was obtained using surface coils in quasi-sagittal planes parallel to the long orbital axis in targeted controlled central, down and up gaze in 14 normal control subjects and in 11 subjects who had undergone prior blepharoplasty. We analyzed changes in anteroposterior position of IO and CPF relative to the anterior edge of the inferior orbital rim during vertical gaze shifts.
Results:
The IO was located more anteriorly and inferiorly in the blepharoplasty group than the control group (p=0.043, p= 0.004, respectively). The IO moved less posteriorly but more inferiorly in infraduction in the blepharoplasty group than in controls. In supraduction, IO position was similar in the two groups. Position of the CPF did not differ significantly between two groups. The IO was closer to the orbital rim in the blepharoplasty than the control group (p=0.045), and the distance from the lower lid skin surface to IO was shorter in the blepharoplasty than the control group (p=0.002).
Conclusions:
Lower lid blepharoplasty significantly alters gaze-dependent IO path, and hence pulling direction, particularly in infraduction. Blepharoplasty also moves the IO path closer to the skin surface. Changes in IO path induced by blepharoplasty could induce vertical strabismus in some cases, perhaps depending upon mechanical characteristics of lower eyelid skin and associated tissues.
Keywords: 722 strabismus •
521 extraocular muscles: structure