Special features of superior oblique hypofunction due to tendon abnormalities.

While most cases of superior oblique (SO) hypofunction represent contractile weakness due to denervation, sometimes the lesion is exclusively in the tendon. This study sought to distinguish the pattern of incomitant strabismus caused by deficiency of SO oculorotary force caused by tendon abnormalities versus that of neurogenic palsy. Clinical and magnetic resonance imaging (MRI) findings of 7 cases of unilateral SO tendon interruption or extirpation were compared with 11 cases of age matched unilateral SO palsy having intact tendons.