Upper eyelid retraction from inferior rectus restriction in dysthyroid orbit disease.

Findings from orbital computed tomography scans have shown inflammatory enlargement of the levator palpebralis superioris complex to be a likely cause of eyelid retraction in dysthyroid (Graves's) ophthalmopathy. We have studied a subgroup of nine dysthyroid patients in whom the eyelid retraction occurs as a relative malposition of the globe and eyelid due to inferior rectus restriction. Our explanation of this phenomenon in nine patients is based on Hering's law. Increased innervation required for a fixating superior rectus muscle to overcome a severely restricted inferior rectus muscle causes an unrestricted levator muscle to open the eyelid abnormally wide relative to the globe. The retraction is best demonstrated with fixation of the involved eye. We have performed inferior rectus recession to correct this type of eyelid retraction in three of our patients.