LAUSR

The current issue of JAMA includes guidelines for vision screening in young children.1,2 The guidelines are thorough and evidence-based. Simply condensed, vision screening is recommended for children older than 3 years; however, the evidence was insufficient to recommend for or against screening for children aged 6 months to 3 years. Screening offers detection of amblyopia (child has eyes with different refractive powers and/or strabismus), high refractive errors, and even anisocoria (unequal size pupils) in patients often unable to self-identify a problem. The proliferation of screening tools underscores the importance, both medical and financial, of screening. Other studies have reported that amblyopia, in particular, occurs in 1% to 6% of children worldwide.3,4 New research suggests that amblyopia, in addition to causing correctable vision problems, may have other deleterious effects on child development; for example, it may slow reading speed, potentially affecting education.5,6 This is all the more reason to detect and treat the condition early. With the availability of noninvasive methods for detecting possible vision problems and the rapidity with which screening can be accomplished, screening is certainly an important tool in the pediatrician’s armamentarium. Before commenting on the effects that screening has on children and their families, several unanswered questions about screening’s benefits should be addressed. These include ethnic variations in refractive errors, a paucity of data on the natural history of refractive errors in the youngest children, and a lack of evidence that screening leads to productive, actionable interventions in very young children. I will avoid comparing and evaluating screening tools because in pediatric vision screening, the screening tools have too often been emphasized over effective interventions. Learning the natural history of vision problems in children should be prioritized. Screening is mostly based on crosssectional data about amblyopia. We know that a certain percentage of children show amblyopia at age 3 years, but we have no idea of the natural history of amblyopia in older or younger children. Clinical experience and treatment studies are persuasive that most children 3 years or older with amblyopia and refractive errors do not experience enough improvement in visual function without treatment to ignore the finding.7 But there are children whose visual function improves over time, who will not develop full-blown amblyopia even if they show early-life indications, and who do not need treatment. Infants in the United States are usually born with significant astigmatism, often severe enough that treatment would be warranted if they were older than 3 years. As months pass, however, the amount of astigmatism diminishes; the axis of the astigmatism (cylinder) may change; and the refractive status of eyes may equalize. Clinically significant changes occur at least to age 1 year and perhaps beyond. Racial and ethnic differences also exist, some of which could be considered abnormal if taken out of context. For example, some Native American children may have substantial amounts of astigmatism. The astigmatism increases with age. The question should be asked whether the astigmatism (which endures to older ages) should be treated with corrective glasses or whether it may improve or worsen on its own in some instances.8 African American and Asian infants also show greater refractive error than white children.8 Children younger than 3 years are often nonverbal, and they may or may not understand the requirements for good screening (eg, holding still). Suppose that a child has anisometropia, and a referral is made, with all its attendant problems, especially parent anxiety. Screening tools may accurately detect anisometropia with enough disparity between eyes to meet guidelines for treatment in older children, but what if the child is, say, as young as 12 months? What is the ophthalmologist to do? Usual practice patterns include a cycloplegic eye examination (instilling eyedrops to control accommodation) to quantify the problem followed by decision making. Do we place the 1or 2-year-old child in glasses? We have no data that the child has amblyopia, since a verbal measure of visual acuity is required, and we do not know what will happen to the child’s refractive status over time. How long should the child wear glasses? Patching and glasses at this early age are based on scant quantitative data. These concerns notwithstanding, conditions arise in infants and young children that require attention. Very high anisometropia, hyperopia, high myopia, and strabismus should be treated to ensure the best possible vision development. These conditions are uncommon, making it hard to advocate mass screening examinations for this age group. Meanwhile, strabismus can usually be detected by parents and pediatricians. The concept that early intervention is important for vision disorders is often untrue. The critical age for treatment of strabismic and anisometropic amblyopia lasts to at least 7 years or even older, and the effect of patching and glasses is about the same no matter the age of intervention in children, at least to age 7 years. These relatively new findings offer a compelling reason for attempts to minimize screening errors, which Related articles at jama.com Opinion