Pseudo inferior oblique overaction, clinical findings, mechanism, and surgical outcomes
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To investigate clinical findings of the pseudo inferior oblique overaction (IOOA) syndrome and the outcomes of strabismus surgery and to discuss the mechanisms proposed for this disease.
This syndrome is defined by Y pattern strabismus with exotropia in upgaze. There is marked abduction and hypertropia of the adducting eye when elevation is carried out in side gaze, but there is no hypertropia of the adducting eye in horizontal side gaze. Sixteen patients were included and surgery was performed in 14 patients. Success of the surgical intervention was defined as correction of the Y pattern, orthotropia in primary position, upgaze, and downgaze.
Thirteen of the sixteen patients were female. The mean age was 9.6 ± 6.1 years. The mean follow-up time was 14.7 ± 16.9 months. Pre-operatively, 12 patients were orthophoric, and four patients were exophoric (4 to 8 PD) in primary position. In downgaze, all patients were orthophoric. Mean exotropic deviation in upgaze was 25.06 ± 5.9 (18 to 40 PD). Fourteen patients underwent surgery with 2-mm bilateral lateral rectus recession and full tendon supraplacement in seven cases, and 2/3 tendon supraplacement in the other seven patients. The success rate of surgery was 92.8% after the first operation, which reached 100% after a second surgical procedure was performed on one of the patients.
Strabismus surgery is effective in correcting the Y pattern in patients with pseudo IOOA. A 2/3 tendon supraplacement combined with 2-mm recession of the lateral rectus muscles is the preferred treatment.
KeywordsPseudo inferior oblique overaction Strabismus surgery Y pattern
The authors of the article express their gratitude for Dr. Kushner’s valuable comments which significantly helped in improving the quality of the study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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