Detection of SO tendon abnormality versus atrophy
Reviewed by Fiona Rowe

This study aimed to evaluate patterns of binocular misalignment in primary gaze, lateral and vertical gaze, and head tilt in patients showing head-tilt dependent hypertropia associated with discontinued superior oblique (SO) tendon but without SO muscle atrophy, versus patients with SO atrophy without tendon abnormalities, i.e., the latter cases being classic neurological SO palsy. The study included 18 patients; seven with SO tendon abnormalities and 11 without. Hypertropia was similar in both groups in all gaze positions except dorsum version with significantly greater deviation in the SO tendon abnormality group. The SO muscle belly was normal in cases of tendon abnormality but atrophic in neurogenic cases. The authors suggest surgical detection of SO laxity would not distinguish SO tendon defects from neurological atrophy, whilst MRI could reliably detect the pathology of the SO belly. Confirmation of SO tendon abnormality versus atrophy would aid in the decision-making for surgical repair of SO defects.

Special features of superior oblique hypofunction due to tendon abnormalities.
Aleassa M, Le A, Demer JL.
STRABISMUS
2021;29(4):243-51.