Surgical Treatments in Inferior Oblique Muscle Overaction

PURPOSE: To compare the outcomes of surgical procedures in the treatment of inferior oblique muscle overaction (IOOA) as a common disorder of ocular motility. METHODS: This retrospective study was performed on patients with primary and secondary IOOA who underwent three surgical treatment procedures including disinsertion, myectomy and anterior transposition, between 2001 and 2011. Type of strabismus, ocular alignment, presence of pre-and post-operative dissociated vertical deviation (DVD), pre- and post-operative degree of IOOA were obtained using specified checklist. RESULTS: A total of 122 eyes of 74 patients with mean age of 13 ± 11.7 (range, 1-51) years were included in this study. Disinsertion was performed on 12 eyes (9.8%), myectomy in 91 eyes (74.6%) and anterior transposition in 19 (15.6%). Preoperative V-pattern and DVD existed in 67 and 17 eyes; after surgery they remained in only 10 and 8 eyes, respectively. The success rate (IOOA <+1), in disinsertion, myectomy and anterior transposition groups were 91.7%, 97.8%, and 89.5%, respectively and these measures did not change after 6 months. Overall, 53.3% (n = 65) and 38.5% (n = 47) of eyes had preoperative esotropia and exotropia. Preoperative hypertropia and hypotropia were observed in 16.4% (n = 20) and 3.3% (n = 4) of eyes, respectively. After surgery there were no cases of additional strabismus. However, residual hypertropia was seen in 9 eyes, while preoperative hypotropia increased in one patient who underwent anterior transposition surgery. Esotropia and exotropia were not observed in any surgical treatment groups postoperatively. CONCLUSION: We conclude that all these three procedures are effective for treatment of primary or secondary IOOA with minimum side-effects.