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E. A. Urrets Zavalia, J. I. Torrealday, F. A. Esposito, H. M. Serra, J. A. Urrets-Zavalia; Downshoot in Infra-adduction in Strabismus With A-pattern: Post Surgical Evolution Following Selected Superior Oblique Surgical Weakening Procedures. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1128.
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To evaluate the occurrence of postsurgical true/pseudo superior oblique muscle overaction (SOOA) following treatment of A-pattern strabismus and its possible causes.
30 patients with A-pattern strabismus and symmetric SOOA were consecutively treated with 3 different superior oblique muscle (SOM) weakening surgical procedures according to degree of presurgical anisotropia and SOOA. 19 patients underwent a posterior partial tenectomy (PPT), 6 a temporal tenotomy (TT) at 4mm from scleral insertion and 5 a posterior transposition recession (PTR). The same procedure was performed in both eyes of a same patient.
Mean postsurgical correction of A-anisotropia was 73.9% in patients treated with PPT, 83.3% with TT and 84% with PTR. Persistence of downshoot in infra-aduction (DSIA) (true/pseudo SOOA) occurred in 12 out of 19 patients (63%) treated with PPT, in 2 of 6 (33%) with TT and in 5 of 5 (100%) of those treated with PTR. Mean DSIA correction was 56.4% in patients treated with PPT, 79.9% with TT and 25% with PTR.
A high prevalence of postsurgical DSIA in patients with A-pattern treated with selective surgical procedures performed on SOM was observed. Apparently all 3 different surgical procedures used were useful in reducing horizontal action of SOM, with less effect on its vertical action. Eliminating A-pattern, natural vertical movements promoted by SOM such as depression in infra-adduction and slight elevatio in infra-abduction would become more evident, giving the impression of SOM hyperfunction exacerbation. As the least traumatic procedure TT gave the lowest occurence of DSIA.
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