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Reoperation in Horizontal Strabismus and Its Related Risk Factors

Zhale Rajavi, Mohammad Gozin, Hamideh Sabbaghi, Narges Behradfar, Bahareh Kheiri, Mohmmad Faghihi


To determine the surgical outcomes and the related risk factors of the second operation in patients with residual horizontal deviations this study has been performed.

In this interventional case series study, a total of 119 patients with a history of reoperation were included (39 exotropia and 80 esotropia). Cases with consecutive strabismus, muscular palsy, systemic disease, lack of ocular fixation and cases who had vertical deviation and dissociated vertical deviation (DVD)>5 prism diopters (pd) were excluded. Medial rectus (MR) resection in residual exotropia (XT) and lateral rectus (LR) resection in residual esotropia (ET) were performed. Unilateral or bilateral operation were considered if the preoperative residual deviation was <20pd or >20pd, respectively. Success of the reoperation was considered if the postoperative angle of deviation was ≤10pd.

Unilateral and bilateral MR resection was performed in 26% and 74% of exotropic patients respectively with more dose response in unilateral cases (2.8 versus 2.6mm/pd). Successful surgical outcomes were observed in 94.9% of exotropic patients. Unilateral and bilateral LR resection was also performed in residual esotropic patients each in 50% of patients. Unilateral cases resulted in more dose response compared to bilateral ones (2.6 versus 2mm/pd) and successful surgical outcomes were observed in 83.8% of esotropic patients. No variable was found as a risk factor of reoperation in the both groups.

Both LR resection and MR resection are easy and predictable surgical approaches with high success rate in residual eso- and exotropic patients. Generally, MR resection is more effective than LR resection. Unilateral operation is less recommended in residual exotropic group due to its lower success compared to the bilateral operation. Unfortunately, none of the mentioned variables were found to be the risk factor of reoperation in our patients.

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