Spectacle correction versus no spectacles for prevention of strabismus in hyperopic children.

backgroundHyperopia in infancy requires accommodative effort to bring images into focus. Prolonged accommodative effort has been associated with an increased risk of strabismus. Strabismus may result in asthenopia and intermittent diplopia, and makes near work tasks difficult to complete. Spectacles to correct hyperopic refractive error is believed to prevent the development of strabismus.

objectivesTo assess the effectiveness of prescription spectacles compared with no intervention for the prevention of strabismus in infants and children with hyperopia. SEARCH

methodsWe searched CENTRAL (2018, Issue 12; which contains the Cochrane Eyes and Vision Trials Register); Ovid MEDLINE; Embase.com; three other databases; and two trial registries. We used no date or language restrictions in the electronic search for trials. We last searched the electronic databases on 4 December 2018. SELECTION CRITERIA: We included randomized controlled trials and quasi-randomized trials investigating spectacle intervention or no treatment for children with hyperopia. We required hyperopia to be at least greater than +2.00 diopters (D). DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodological procedures. The primary outcome was the proportion of children with manifest strabismus, as defined by study investigators. Other outcomes included the amblyopia, stereoacuity, and the effect of spectacle use of strabismus and visual acuity. We also collected information on change in refractive error as a measurement of the interference of emmetropization. MAIN

resultsWe identified four randomized controlled trials (985 children enrolled who were aged six months to less than 36 months) in this review. Three trials were in the UK with follow-up periods ranging from one to 3.5 years and one in the US with three years' follow-up. Investigators reported both incidence and final status regarding strabismus. Evidence of the incidence of strabismus, measured in 804 children over three to four years in four trials was uncertain although suggestive of a benefit with spectacle use (risk ratio (RR) 0.65, 95% confidence interval (CI) 0.41 to 1.02). We have very low confidence in these results due to high risk of bias, inconsistency, and imprecision. When assessed as the proportion of children with strabismus at the end of three years' follow-up, we found a similar level of evidence for an effect of spectacles on strabismus as reported in one study (RR 1.00, 95% CI 0.31 to 3.25; 106 children). We have very low confidence in these results because of low sample size and risk of bias. One trial reported on the risk for developing amblyopia and inadequate stereoacuity after three years in 106 children. There was unclear evidence for a decreased risk of developing amblyopia (RR 0.78, 95% CI 0.31 to 1.93), and limited evidence for a benefit of spectacles for prevention of inadequate stereoacuity (RR 0.38, 95% CI 0.16 to 0.88). We have very low confidence in these findings due to imprecision and risk of bias. The risk of not developing emmetropization is unclear. One trial reported on the proportion of children not achieving emmetropization at three years' follow-up (RR 0.75, 95% CI 0.18 to 3.19). One trial suggested spectacles impede emmetropization, and one trial reported no difference. These two trials could not be combined because the methods for assessing emmetropization were different. With the high risk of bias and inconsistency, the certainty of evidence for a risk for impeding or benefiting emmetropization is very low. Based on a meta-analysis of four trials (770 children), the risk of having visual acuity worse than 20/30 measured up to three years of age or at the end of three years of follow-up was uncertain for children with spectacle correction compared with those without correction (RR 0.87, 95% CI 0.64 to 1.18; very low confidence due to risk of bias and imprecision). AUTHORS'

conclusionsThe effect of spectacle correction for prevention of strabismus is still unclear. In addition, the use of spectacle on the risk of visual acuity worse than 20/30, amblyopia, and inadequate emmetropization is also unclear. There may be a benefit on prevention of inadequate stereoacuity. However, these effects may have been chance findings or due to bias.