Comparison of outcome of inferior oblique weakening procedures, myectomy and anterior transposition, from western India

Abstract

Context: Inferior oblique (IO) weakening is one of the commonest surgical procedures on the oblique muscles. Purpose: To compare the results of two IO weakening procedures, myectomy, and anterior transposition, done for IO over-action and dissociated vertical deviation (DVD). Setting and design: Tertiary eye-care center. Retrospective review Materials and Methods: Patients operated for IO over-action and DVD were studied. All patients had undergone a comprehensive ocular examination with full orthoptic evaluation and cycloplegic refraction. In the anterior transposition of IO, the IO muscle was recessed from its insertion and placed lateral to the insertion of the inferior rectus. In myectomy, the IO tendon was cut at two sites 5 mm apart and the cut ends cauterized and left free. The outcome measure was pre and post-operative IO action measurement. Statistical analysis: T-test. Results: Eighty six children (128 eyes) underwent IO weakening procedures, 81 (62.4%) were myectomy and 47 (36.2%) were anterior transpositions. The average age was 8.9 years (standard deviation, SD 3.51), 53 (61.6%) were girls. Twenty-three had DVD and 42 patients had bilateral IO surgeries. Thirty-eight (44.2%) had esotropia and 47 (54.6%) had exotropia co-existent; one had only primary IO over-action. The pre-and post-operative IO over-action was 1.61 and 0.59 for myectomy and 1.61 and 0.29 for anterior transposition, respectively. On comparing the pre- vs post-IO action, P < 0.001 for both techniques, but post-operative anterior transposition versus myectomy had P = 0.156 by the t-test. Conclusion: Both techniques were effective and the difference between the two techniques was not statistically significant.