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

Background Hyperopia 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. Objectives To assess the effectiveness of prescription spectacles compared with no intervention for the prevention of strabismus in infants and children with hyperopia. Search methods We 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 results We 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 childr