Abstract
Purpose::
To evaluate the results of superior oblique tendon lengthening procedure or superior oblique tenotomy in the treatment of A-pattern strabismus.
Methods::
A clinical study was conducted on 32 patients who underwent superior oblique tendon lengthening (9 patients,14 eyes) or superior oblique tenotomy (23 patients, 39 eyes) for A-pattern strabismus between June 1996 and June 2004. Thirteen male and 19 female patients were included, ranging in age from 6 to 31 years (mean: 15.6 years). Pre- and post-operative eye positions, reduction of A-pattern strabismus, vertical and horizon deviations, superior oblique muscle function and binocular function were examined and analyzed in patients underwent either a unilateral or bilateral superior oblique tendon lengthening, or superior oblique tenotomy based on the patient's clinical diagnosis (follow-up range: 6 to 48 months, mean: 16.8 months).
Results::
Eight of 9 patients (77.8 %) who underwent tendon lengthening and 19 of 23 patients (82.6%) that underwent superior oblique tenotomy had complete normalization of superior oblique action. The corrections of vertical deviation of superior oblique function were 85.7% in tenotomy group and 84.6% in tendon lengthening group. There was no significant difference for correction of A-pattern strabismus between the two surgical procedures (p > 0.05). The average correction of strabismus between upgaze and downgaze was 26.94±10.39 prism diopters (delta) for the both surgical procedures.Superior oblique muscle insufficiency occurred postoperatively in 38.5% (15 of 39 eyes) of tenotomy patients, compared to only 7.1 % (1 of 14 eyes) of superior oblique tendon lengthening (p <0.05). The residual overaction of superior oblique muscle in eyes underwent the superior oblique tendon lengthening was greater than those underwent superior oblique tenotomy (50% vs. 15.4%, respectively, p < 0.05).
Conclusions::
Our study demonstrates that either superior oblique tendon lengthening or superior oblique tenotomy is safe and effective in treatment of patients with A-pattern strabismus accompany with superior oblique muscle overaction. The tendon lengthening is recommended for patients with mild superior oblique overaction and for patients with better binocular function. The caution should be guided for the both weakening procedures in patients with A-pattern strabismus under 20 prism diopters.
Keywords: strabismus: treatment • eye movements: recording techniques • esotropia and exotropia