Prognostic preoperative factors for successful outcome of surgery in horizontal strabismus

Surgery for horizontal strabismus reportedly has a success rate of 60%-80%. However, which preoperative factors are predictive of this success is not clear.

To identify prognostic factors those are predictive of successful outcome in horizontal strabismus surgery.

Observational analytical study using multiple logistic regression (MLR).

We assessed the medical records of patients who had undergone first-time horizontal muscle strabismus surgery between 2002 and 2013, where complete follow-up data were available for ≥6 weeks, and also, we collected data prospectively on patients operated between January 2014 and September 2015. Successful outcome was defined as a postoperative angle of deviation within 10 prism diopter of orthophoria at ≥6 weeks postoperatively. Independent variables considered were age at onset, age at surgery, duration, gender, deviation - type and amount, logMAR visual acuity (VA) - mean and of the poorer eye, mean refractive error, amount of anisometropia, and presence of dense amblyopia. Only those with P < 0.2 on univariate analyses (UAs) were included in the MLR, with significance set at P ≤ 0.05.

UA (Chi-square for categorical variables and t-tests for continuous variables), followed by logistic regression analysis.

Of 113 patients, on UA, type of deviation (P = 0.01), age at surgery (P = 0.16), absence of dense amblyopia (P = 0.002), and logMAR VA of the poorer eye (P = 0.005) qualified for the inclusion in MLR. On MLR, esotropia (ET) (odds ratio [OR]: 4.46) and absence of dense amblyopia (OR: 5.90) were associated with success.

With an overall success rate of 83%, ET and absence of dense amblyopia were significantly predictive of surgical success.