[Investigations on cyclotorsion changes following strabismus surgery in superior oblique palsy patients].

OBJECTIVE: To investigate cyclotorsion changes after strabismus surgery in superior oblique palsy patients.
METHODS: Forty patients (50 eyes) underwent myotomy of inferior oblique (15 patients, 15 eyes), partial myectomy of inferior oblique (15 patients, 15 eyes) or myotomy of inferior oblique combined with inferior rectus recession on the other eye (10 patients, 20 eyes) for treatment of monocular superior oblique palsy. Objective cyclotorsion were examined pre-operation, as well as 1, 7, 30, and 90 d post-operation with fundus photograph and quantitive measurement. Vertical deviation and ocular movement were also assessed before and after surgery. Fundus photograph were also examined in 30 normal persons (60 eyes) without strabismus.
RESULTS: The fovea-to-disc angle of normal people was 6.7°±2.5° in the right eye, 5.9°±2.3° in the left eye, and 12.6°±4.3° when combined. The cyclotorsion angle was not statistically significant between two eyes (t=1.29, P=0.20). For the monocular superior oblique palsy patients, preoperative fovea-to-disc angle was 14.3°±6.6° in the affected eyes, 12.2°±4.8° in the fellow eyes, and 26.5°±10.3° when combined. The objective cyclotorsion was also not statistically significant between two eyes (t=1.64, P=0.11). The comparison of total cyclotorsion angle of both eyes showed significant difference between normal people and patients. The fovea-to-disc angle of 1, 7, 30 and 90 d after operation were 11.7°±4.3°, 11.9°±4.9°, 13.5°±5.2° and 15.9°±3.6° respectively. The comparison of objective ocular cyclotorsion for both eyes showed significant difference pre- and post-operation (F=40.13, P<0.01). There is a gradual increasing trend of postoperative excyclotorsion angle with the prolonged time. There were statistically significant difference between 90 d and 1 d, 7 d after surgery. The two inferior oblique weakening procedures, myotomy of inferior oblique and partial myectomy of inferior oblique produced equitable amount of incyclotorsion shift with no statistical difference. The difference between the cyclotorsion change induced by myotomy of inferior oblique and inferior rectus recession in counter side was also not statistically significant.
CONCLUSIONS: Monocular superior oblique palsy patients had fundus excyclotorsion change that was nearly equally distributed between two eyes. Weakening the inferior oblique and inferior rectus could correct ocular excyclotorsion, the regression trend was observed 90 d after surgery. Both myotomy and partial myectomy of inferior oblique were equally effective in the correct of ocular cyclotorsion and vertical deviation.