Monocular elevation deficiency with contralateral superior oblique muscle tendon laxity

Monocular elevation deficiency with a tight ipsilateral inferior rectus muscle and fixation preference for the contralateral eye is a well recognized entity in strabismus. Most descriptions of the condition, however, do not document oblique muscle forced duction testing in the contralateral eye. The purpose of this report is to raise awareness that monocular elevation deficiency can be associated with, and may be secondary to, a floppy (lax) superior oblique muscle tendon in the contralateral fixating eye.

Retrospective case series.

All 4 patients were previously diagnosed with congenital monocular elevation deficiency. All had variable head tilt towards the hypotopic eye, pseudoptosis with mild elevation limitation in that eye, and bilateral fundus excyclotorsion. In addition to inferior rectus muscle restriction in the hypotropic eye, forced duction testing was significant for contralateral superior oblique muscle tendon laxity.

Fixation preference for the eye with lax superior oblique muscle tendon may have led to a tight inferior rectus muscle in the non preferred eye. However, a congenital association between tight inferior rectus muscle and a lax superior oblique muscle tendon in the other eye cannot be ruled out. Patients diagnosed with monocular elevation deficiency should have careful attention to forced duction testing of the contralateral superior oblique muscle tendon.