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Evidence-based medicine is the practice of making medical decisions based on evidence gained from applying the scientific method. Published studies are evaluated using three key questions: "Are the results valid?"; "What are the results?"; and "Can the results be applied to my patients?" The hierarchy of study methods for obtaining evidence is, in order from least to most useful: laboratory research, editorials, case reports and series, case-control studies, cohort studies, and randomized clinical trials. Retrospective case series can suffer from problems such as selection of a biased sample, mixing of treatment effects, and lack of control group. Randomized clinical trials (and meta-analyses of multiple trials) provide the highest level of evidence because randomization limits confounding and prevents bias of treatment assignment. In addition, randomized trials have standardization of interventions, prospective data collection, and masked outcome measures. Although every question cannot be addressed by a randomized clinical trial, the best available evidence should be sought and used to guide treatments.

In preverbal children with strabismus, binocular fixation pattern is often assessed to detect amblyopia. In those children without strabismus or with small angle deviations, the induced tropia test is frequently used instead. There are many variations in the techniques used to perform these tests and in their interpretations. This paper reviews data which correlates the results of these tests with recognition visual acuities in older children. In addition, a scoring system is presented that quantitates fixation preference by the induced tropia test and aids in assessing depth of amblyopia and in monitoring treatment response.

Preoperatively, strabismus surgeons need to obtain informed consent, identify any ocular or systemic risk factors, decide on the preferred method of anesthesia, and determine whether the patient is an appropriate candidate for an adjustable suture technique. Three major categories of complications should be listed on the consent form: Loss of vision, double vison, and need for reoperation. If a patient is at particulary high risk to have one of these complications, then the surgeon should emphasize this point during the preoperative discussion. The incidence of visual loss after strabismus surgery due to anterior segment ischemia, retinal detachment, or endophthalmitis is approximately 1 in 7,400 cases. The preferred method of anesthesia depends on the procedure planned, the age and general health status of the patient, and whether or not an adjustable suture technique is to be utilized. At the conclusion of the preoperative discussion, the patient should be well informed and comfortable with the choice or procedure, have reasonable postoperative expectations in terms of diplopia, and be prepared for any unexpected complications.