Purpose: To describe the clinical findings and surgical results of superior oblique palsy with class III tendon anomaly.
Design: Observational case series.
Methods: One hundred and forty-one cases of congenital and idiopathic superior oblique palsy were operated on by one surgeon (M.S.) between September 1, 1995 and August 31, 2007. The superior oblique tendons were explored in 26 cases. Among these, five cases were found to have the distal end of the tendon inserted into the Tenon capsule. Preoperative eye alignment, visual acuity, stereopsis measured with Titmus stereo acuity tests (Stereo Fly SO-001; Stereo Optical Co, Chicago, Illinois, USA), and magnetic resonance imaging findings were collected from the patients' records. Main outcome measures included preoperative eye position, surgical results, and stereoscopic acuity. Stereopsis and the amount of vertical deviation were compared in cases with class I, II, and IV tendon anomalies.
Results: A total of eight surgeries were performed on five patients with class III superior oblique tendon anomaly. Three muscles were operated on for each patient. The amount of vertical deviation was not significantly different from other types of tendon anomaly. Patients with class I to III tendon anomalies obtained good stereopsis after strabismus surgery, whereas cases with class IV anomaly achieved only limited stereopsis. The number of surgeries performed was significantly higher in cases with class IV anomaly.
Conclusions: Without careful search of the Tenon capsule, the condition can be misdiagnosed as an absent tendon. Strengthening the superior oblique tendon in the Tenon capsule can improve the alignment significantly.