Anterior Nasal Superior Oblique Tendon Syndrome: A Case Series.

PURPOSE: To evaluate the clinical characteristics and management of patients with an anteriorly and nasally inserted superior oblique tendon.

DESIGN

Retrospective interventional case series.

METHODS

Institutional clinical records between 2020 and 2024 were retrospectively reviewed for 9 consecutive patients in whom the superior oblique (SO) tendon was inserted anterior to the equator and nasal to the superior rectus muscle. Information collected included age, sex, ocular and surgical history, preoperative and postoperative data (ophthalmologic examinations, strabismus measurements, ductions and versions), intraoperative findings, need for additional surgery, and follow-up time.

RESULTS

All nine patients were found to have an anomalous insertion of the SO tendon. Three were of congenital origin and six were acquired following ocular surgery. Among the acquired cases, all but one resulted from incarceration of the tendon from postsurgical scar tissue formation. The remaining acquired case was due to a prior deliberate anterior and nasal transposition of the superior oblique. This case series demonstrated varying degrees of vertical deviation, lateral incomitance, and limited depression. Repositioning the SO to its normal insertion site yielded equivocal improvement in ocular alignment.

CONCLUSION

Anterior nasal superior oblique tendon syndrome is a rare clinical entity characterized by an antidepressor effect. Vertical deviations, hypertropia worse in downgaze, limited depression worse in adduction for congenital cases and in abduction for acquired cases, and lateral incomitance may be indicative of this anomaly. In acquired cases following surgery, additional findings may include limited depression worse in abduction, esotropia in abduction, V-pattern esotropia, and enophthalmos in downgaze. Surgical repositioning of the SO along its normal anatomical trajectory is recommended for treatment. However, outcomes may be variable and achieving a complete resolution of this syndrome can be challenging.