Connective tissues reflect different mechanisms of strabismus over the life span

Abstract

Connective tissue pulleys determine extraocular muscle force directions and pulley heterotopy can induce strabismus. The etiology and type of pulley abnormalities vary with patient age, resulting in different but predictable types presentations of strabismus. Magnetic resonance imaging (MRI) was obtained in 95 patients with pulley heterotopy, of whom 56 had childhood-onset pattern strabismus, and was compared with published data on 28 patients aged 69±12years who had sagging eye syndrome. Control data were from age-matched normal controls with no strabismus. Patients with childhood-onset strabismus had intact lateral rectus-superior rectus band ligaments and straight extraocular muscle paths but exhibited pulley array A pattern-associated incyclorotation or V pattern-associated excyclorotation. Rectus transposition surgery collapsed patterns. Patients with sagging eye syndrome exhibited blepharoptosis, superior sulcus defect, and inferolateral displacement of rectus pulleys with elongation of extraocular muscles that followed curved paths. Symmetrical lateral rectus pulley sag was associated with divergence paralysis esotropia; asymmetrical sag > 1mm, with cyclovertical strabismus. Both lateral rectus resection and medial rectus recession treated divergence paralysis esotropia. Partial vertical rectus tenotomy treated cyclovertical strabismus. Childhood onset pulley abnormalities are associated with A or V pattern strabismus and external anatomical features suggest that these pulley defects are probably congenital. Adult onset pulley defects commonly result from age-related tissue involution and external features such as adnexal laxity are also helpful in recognizing involution as a possible etiology of strabismus.