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M.A. Najera Covarrubias, K.W. Wright, M.C. Mocan, P. Hong; Redefining Stretched Scar "Tendon Dehiscence" in Secondary Strabismus . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2746.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the incidence and characteristics of tendon dehiscence (stretched scar) as a cause of overcorrection or undercorrection after strabismus surgery. Methods: Retrospective study of strabismus reoperation cases diagnosed as stretched scar based on the appearance of the muscle-sclera attachment at the time of surgery between 1/2000 and 11/2002. Ocular motility was evaluated before and after surgery. Pathologic examinations were performed in 6 patients. Results: Twenty (n=20) of 121 (16.52%) patients who underwent a reoperation strabismus surgery were diagnosed with stretched scar as the cause of their secondary strabismus. Median age was 28.8 years (range= 5 to 79 years); 8 males and 12 females. Five of the 20 patients were primarily operated by one of the authors, and the rest had the primary surgery elsewhere. Seventeen patients (85%) had an overcorrected strabismus and three (15%) an undercorrected. No patient had immediate onset of the strabismus after the primary strabismus surgery, but 95% of them occurred within 3 months. Twenty-five muscles were involved (21 medial rectus, 3 lateral rectus, 1 inferior rectus). Five cases were bilateral (4 involved medial rectus OU, 1 involved lateral rectus OU). Recession procedure as the primary previous surgery was performed in 22 muscles. A primary resection procedure was performed in 3 muscles. Median preoperative versions in the field of action of involved muscles were -1.26, SD =0.792 (normal in four, -1 in eleven, -1.5 in two, -2 in six, -2.5 in one, -3 in one). Median postoperative versions were -0.08, SD=0.277 (normal in twenty-three, -1 in two). Histopathologic study showed fibrotic scar tissue and absence of muscle fibers. Conclusions: Stretched scar should be considered as an important cause of unfavorable outcomes after strabismus surgery (overcorrected-undercorrected). In contrast to a slipped muscle that occurs immediately after surgery, affects versions in a large degree, and is related to large-angle postoperative deviations, stretched scar occurs late after surgery causing a slow and progressive increasing deviation with versions minimally affected, so the diagnosis of stretched scar could be easily missed. Although unclear, it could be related to loss of suture strength or to collagen abnormalities. In contrast to stretched scar, slipped muscle is related to an improper suture placement with a detached muscle insertion to sclera.
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