Interventions for intermittent exotropia

Background: The clinical management of intermittent exotropia (X(T)) has been discussed extensively in the literature, yet there remains a lack of clarity regarding indications for intervention, the most effective form of treatment, and whether there is an optimal time in the evolution of the disease at which any given treatment should be carried out.

Objectives: The objective of this review was to analyze the effects of various surgical and non-surgical treatments in randomized controlled trials (RCTs) of participants with intermittent exotropia, and to report intervention criteria and determine whether the treatment effect varies by age and subtype of X(T).

Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2021, Issue 1), which contains the Cochrane Eyes and Vision Trials Register; Ovid MEDLINE; Ovid Embase; Latin American and Caribbean Health Science Information database (LILACS); the ISRCTN registry; ClinicalTrials.gov, and the WHO ICTRP. The date of the search was 20 January 2021. We performed manual searches of the British Orthoptic Journal up to 2002, and the proceedings of the European Strabismological Association (ESA), International Strabismological Association (ISA), and American Association for Pediatric Ophthalmology and Strabismus meeting (AAPOS) up to 2001.

Selection criteria: We included RCTs of any surgical or non-surgical treatment for intermittent exotropia.

Data collection and analysis: We followed standard Cochrane methodology.

Main results: We included six RCTs, four of which took place in the United States, and the remaining two in Asia (Turkey, India). A total of 890 participants with basic or distance X(T) were included, most of whom were children aged 12 months to 10 years. Three of these six studies were from the 2013 version of this review. Overall, the included studies had a high risk of performance bias as masking of participants and personnel administering treatment was not possible. Two RCTs compared bilateral lateral rectus recession versus unilateral lateral rectus recession with medial rectus resection, but only one RCT (n = 197) reported on the primary outcomes of this review. Bilateral lateral rectus recession likely results in little difference in motor alignment at near (MD 1.00, 95% CI -2.69 to 4.69) and distance (MD 2.00, 95% CI -1.22 to 5.22) fixation as measured in pupillary distance using PACT (moderate-certainty evidence). Bilateral lateral rectus recession may result in little to no difference in stereoacuity at near fixation (risk ratio (RR) 0.77, 95% CI 0.35 to 1.71), adverse events (RR 7.36, 95% CI 0.39 to 140.65), or quality of life measures (low-certainty evidence). We conducted a meta-analysis of two RCTs comparing patching (n = 249) with active observation (n = 252), but were unable to conduct further meta-analyses due to the clinical and methodological heterogeneity in the remaining trials. We found evidence that patching was clinically more effective than active observation in improving motor alignment at near (mean difference (MD) -2.23, 95% confidence interval (CI) -4.02 to -0.44) and distance (MD -2.00, 95% CI -3.40 to -0.61) fixation as measured by prism and alternate cover test (PACT) at six months (high-certainty evidence). The evidence suggests that patching results in little to no difference in stereoacuity at near fixation (MD 0.00, 95% CI -0.07 to 0.07) (low-certainty evidence). Stereoacuity at distance, motor fusion test, and quality of life measures were not reported. Adverse events were also not reported, but study authors explained that they were not anticipated due to the non-surgical nature of patching. One RCT (n = 38) compared prism adaptation test with eye muscle surgery versus eye muscle surgery alone. No review outcomes were reported. One RCT (n = 60) compared lateral rectus recession and medial rectus plication versus lateral rectus recession and medial rectus resection. Lateral rectus recession and medial rectus plication may not improve motor alignment at distance (MD 0.66, 95% CI -1.06 to 2.38) (low-certainty evidence). The evidence for the effect of lateral rectus recession and medial rectus plication on motor fusion test performance is very uncertain (RR 0.92, 95% CI 0.48 to 1.74) (very low-certainty evidence).

Authors' conclusions: Patching confers a clinical benefit in children aged 12 months to 10 years of age with basic- or distance-type X(T) compared with active observation. There is insufficient evidence to determine whether interventions such as bilateral lateral rectus recession versus unilateral lateral rectus recession with medial rectus resection; lateral rectus recession and medial rectus plication versus lateral rectus recession and medial rectus resection; and prism adaptation test prior to eye muscle surgery versus eye muscle surgery alone may confer any benefit.