contracture

A contracture is an inability of an extraocular muscle to relax that can lead to permanent structural changes, with the loss of elasticity becoming irreversible.¹ Clinically, the term refers to increased resistance of the muscle to passive stretching, and the loss of elasticity has been related to atrophy of muscle fibers and hyalinization of the muscle.²

Contracture of the antagonist is a characteristic feature of a paralytic deviation, and it can overshadow the weak action of the paralyzed muscle and persist long after the paralysis has subsided.² When the patient fixates with the non-paretic eye, the ipsilateral antagonist of the palsied muscle stays permanently contracted, and fibrous tissue may replace some of its elastic tissue within days to about 4 weeks of the palsy.³ The contracture exaggerates the original deviation and enlarges the Hess plot in the field of action of that antagonist.³

A forced duction test shows the mechanical restriction, which must be removed before any muscle transposition, usually by maximal recession of the contractured antagonist.⁴ Alternate occlusion can help prevent contracture after a palsy.³