This is a retrospective cohort study of all patients over 12-years old undergoing strabismus surgery under a single surgeon in a tertiary referral centre in Toronto, Canada. The aim of the study is to determine the role of achieving immediate target angle on the success of strabismus surgery with either adjustable or non-adjustable sutures. The definition of the target angle with esotropia and vertical deviation was within 4 prism dioptres (PD) of orthotropia and for patients with exotropia between orthotropia and 8PD of esotropia. Success was defined as alignment within 10PD for horizontal rectus surgery and within 5PD of orthotropia for vertical rectus surgery, without diplopia or reoperations. The main outcome measure was surgical success rate. Three hundred and fifty-three patients were included in this study with a mean follow-up of 13.9 (4-132) months. Patients achieving the target angle immediately postoperatively had a higher success rate than patients who did not (83.6% vs. 63.7%, p<0.0001, OR 2.9, 95% CI 1.8 to 4.9). When the target angle was achieved, adjustable and non-adjustable sutures had similar success (84.8% and 80.9%, respectively). Patients undergoing adjustable suture surgery were more likely to obtain the target angle (75% vs. 54%, p<0.0001). Success for exotropia was significantly higher when the immediate target angle was achieved (86.4% vs. 58.7%, p<0.0001). For esotropia and vertical deviations, a similar beneficial effect was not shown. On multiple logistic regressions analysis, sex, amblyopia, binocularity and reoperation were not significant factors in surgical success. The authors stated that the results of this study suggest that achieving the immediate target angle is the most significant factor in the success of strabismus surgery, especially for exotropia, with adjustable suture surgery results in a higher proportion of patients achieving this target angle. However, the limitations of the study include the data on vertical deviations was limited due to low numbers and therefore no firm conclusion can be drawn. The other shortfall included that this was a large tertiary referral centre such that the cases seen were of more complicated patients and many were seen from remote areas. The authors suggest that a prospective randomised controlled trial remains the gold standard to assess the effect of target angles and whether using adjustable sutures is important in achieving this goal.

Achieving postoperative target range increases success of strabismus surgery in adults: a case for adjustable sutures?
Mireskandari K, Schofield J, Cotesta M, et al.
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Jonathan Chan

Royal Hallamshire Hospital, Sheffield, UK.

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