Prognostic preoperative factors for successful outcome of surgery in horizontal strabismus

Abstract

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

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

Settings and design: Observational analytical study using multiple logistic regression (MLR).

Subjects and methods: 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.

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

Results: 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.

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

Keywords: Horizontal strabismus; prognostic factors; successful outcome.