Magnetic Resonance Imaging of Globe Translation in Abducens Palsy

Abstract

PurposeIt has been supposed that rectus muscle paralysis would cause proptotsis due to reduction in active posterior tension. This study aimed to test this proposition by evaluating globe translation during horizontal duction in abducens palsy. DesignProspective, single-center, fellow-eye controlled, case series. MethodsHorizontal globe rotation and translation were quantified using orbital MRI of patients with isolated unilateral abducens nerve palsy without other ocular motility disorder. Unaffected fellow eyes served as controls. Digital image analysis was performed. ResultsA total of 5 female and 2 male patients of mean age 52±15 years (standard deviation) were included. The average esotropia was 39.0±9.7Δ. Mean adduction was similar at 54.9±10.4° in palsied eyes and 52.0±7.1° in fellow eyes. However, abduction in palsied eyes was significantly less at -11.4±7.1° than -37.1±11.4° in fellow eyes (P=0.0023). Average anteroposterior translations in adduction was 0.46±0.42 mm in palsied orbits, similar to 0.35±0.47 mm in fellow orbits (P=0.90). Anteroposterior translation in abduction averaged 0.17±0.53 mm in palsied orbits, similar to 0.27±0.73 mm in fellow orbits (P=0.80). Average horizontal translation in adduction at -0.32±0.23 mm in palsied orbits was statistically similar to -0.12±0.44 mm in fellow orbits (P=0.54). Average horizontal translation in abduction at 0.19 ± 0.18 mm in palsied orbits was similar to 0.33±0.15 mm in control orbits (P=0.38). ConclusionAbducens palsy does not alter normal eye translation during horizontal duction.