Abstract
Purpose To further define the clinical features of patients with inferior oblique muscle overaction (IOOA) and evaluate the surgical results in a subgroup of these patients. Methods The medical records of 173 patients who underwent inferior oblique muscle (IO) weakening surgery due to primary or secondary IOOA were retrospectively reviewed. The patients were assigned a surgical group based on severity of IOOA and presence of dissociated vertical deviation (DVD) or hypertropia. Patients with +1 or +2 IOOA underwent recession, patients with +3 or +4 IOOA underwent myectomy, and patients with any grade of IOOA and DVD or hypertropia underwent anterior transposition (AT) surgery. Results A total of 286 eyes of 173 patients who underwent surgery due to IOOA were included in the study. IOOA was accompanied by esotropia, exotropia, abnormal head posture (AHP), pattern strabismus, convergence insufficiency, DVD, facial asymmetry, and nystagmus. The most common comorbid disorder was esotropia. The recession was used in 173 eyes, myectomy in 64, and AT in 49. Surgical success was obtained in 96.0% of eyes that underwent recession, in 98.4% of eyes that underwent myectomy, and in 93.9% of eyes that underwent AT. In the follow-up, IOOA occurred in the fellow eye in 36.1% of patients who underwent unilateral surgery. Conclusions This study is a comprehensive report on the concomitants of the IOOA. Also, it showed that all of the three surgical procedures including recession, myectomy, and AT are effective in the surgical management of IOOA when performed in select patient groups.
Highlights
Inferior oblique muscle overaction (IOOA) manifests by overelevation of the eye in adduction and is frequently associated with horizontal deviations
A detailed history was obtained from all patients and followed by a complete eye examination including cycloplegic refraction, best spectacle-corrected visual acuity (BSCVA), fundus examination, and measurement of the deviation in diagnostic gaze positions at near and at distance by prism and alternate cover test. e severity of IOOA was graded from 0 to +4 as follows: (0) no IOOA, (+1) mild upwards deviation of the pupil from the horizontal line in adduction, (+2) upper margin of the pupil becomes aligned to the margin of the upper lid in adduction, (+3) superior half of the pupil covered by the upper lid in adduction, and (+4) the entire pupil covered by the upper lid in adduction
V pattern was diagnosed in 35 patients (20.2%), dissociated vertical deviation (DVD) in 11 (6.3%), nystagmus in 7 (4.0%), and facial asymmetry in 7 (4.0%)
Summary
Inferior oblique muscle overaction (IOOA) manifests by overelevation of the eye in adduction and is frequently associated with horizontal deviations. It is reported in 70% of patients with esotropia and 30% of patients with exotropia. Primary type is frequently bilateral and its etiology is unclear, but secondary type is unilateral and is caused by ipsilateral superior oblique (SO) palsy or contralateral superior rectus palsy [1,2,3,4]. Surgical weakening of the inferior oblique muscle (IO) is performed either unilaterally or bilaterally because of functional and/or aesthetic reasons in treatment of the primary IOOA or secondary IOOA due to SO palsy. Various surgical procedures have been described to weaken the IO, including tenotomy, myotomy, myectomy, recession, extirpation-denervation, hang-back recession, nasal transposition, muscle fixation, anterior transposition (AT), and graded AT [4, 7,8,9]
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