Tuesday, February 1, 2011

US Task Force Issues Updated Statement on Visual Screening in Young Children

From Medscape Medical News

Laurie Barclay, MD

January 31, 2011 — The 2004 US Preventive Services Task Force (USPSTF) statement about screening for visual impairment in children 1 to 5 years old has been updated and published online January 31 in Pediatrics.

"The USPSTF recommends vision screening for all children at least once between the ages of 3 and 5 years, to detect the presence of amblyopia or its risk factors (grade B recommendation)," write Mary Barton, MD, from the Agency for Healthcare Research and Quality, Center for Primary Care, Prevention, and Clinical Partnerships in Rockville, Maryland, and colleagues from the USPSTF. "The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of vision screening for children <3 years of age (I statement)."

In developing its updated recommendations, the USPSTF considered evidence from a systematic review of the association of screening for visual impairment in children 1 to 5 years old with improved health outcomes, the accuracy of risk factor evaluation and screening tests, the efficacy of early detection and intervention, the potential harms of screening and treatment, and the net benefit of screening in this population. However, the USPSTF respects the need for clinical or policy decisions to be based on additional considerations. Therefore, they recommend that clinicians and policy makers tailor their decisions to the specific patient or situation.

"Approximately 2% to 4% of preschool-aged children have amblyopia, an alteration in the visual neural pathway in the developing brain that can lead to permanent vision loss in the affected eye," the statement authors write.
"Amblyopia usually occurs unilaterally but can occur bilaterally. Identification of vision impairment before school entry could help identify children who may benefit from early interventions to correct or to improve vision."
On the basis of the evidence, the USPSTF concluded with moderate certainty that screening for visual impairment in children ages 3 to 5 years had a moderate net benefit.

Screening tests that can be used in primary care to identify visual impairment in children include visual acuity tests, stereoacuity tests, the cover-uncover test, and the Hirschberg light reflex test (for ocular alignment/strabismus). Also potentially useful are autorefractors, or automated optical instruments that detect refractive errors and photoscreeners, or instruments that detect amblyogenic risk factors and refractive errors.

Evidence was adequate that vision screening tools are reasonably accurate in the detection of visual impairment, including refractive errors, strabismus, and amblyopia, and that early treatment for amblyopia, including cycloplegic agents such as atropine or patching of the nonaffected eye, and eyeglasses, for children 3 to 5 years old is associated with improved visual outcomes. For children younger than 3 years, however, evidence was inadequate that early treatment of amblyopia results in better visual outcomes.

Evidence was limited regarding psychosocial or other harms of screening for children at least 3 years old. False-positive screening results could result in overprescribing of corrective lenses or reversible loss of visual acuity because of patching of the nonaffected eye. For children younger than 3 years, evidence of the harms of screening and treatment was inadequate.

On the basis of the evidence, the USPSTF concluded with moderate certainty that screening for visual impairment in children ages 3 to 5 years had a moderate net benefit. For children younger than 3 years, however, the USPSTF concluded that the benefits of vision screening are uncertain and that the balance of benefits and harms cannot be determined for this age group. The USPSTF did not find adequate evidence to determine the optimal screening interval.

Review: Efficacy of Vision Screening Limited

An accompanying updated evidence-based review by Roger Chou, MD, from Oregon Evidence-Based Practice Center, Oregon Health & Science University in Portland, and colleagues aimed to evaluate the efficacy of screening preschool-aged children for impaired visual acuity on health outcomes. The reviewers searched MEDLINE from 1950 to July 2009 and the Cochrane Library through the third quarter of 2009, reviewed bibliographies of identified articles, and consulted experts.

They found that direct evidence was limited regarding the efficacy of preschool vision screening for improving visual acuity or other clinical outcomes and did not adequately resolve whether screening is more effective than no screening. Indirect evidence included the ability of several screening tests to detect vision problems in preschool-aged children.

Diagnostic accuracy was not clearly different in different age categories, but testability rates were generally lower in children 1 to 3 years old. Compared with no treatment, treatments of amblyopia or unilateral refractive error were associated with mild improvements in visual acuity, but no study to date assessed school performance or other functional outcomes.

"Although treatments for amblyopia or unilateral refractive error can improve vision in preschool-aged children and screening tests have utility for identifying vision problems, additional studies are needed to better understand the effects of screening compared with no screening," the review authors write.

Commentary: Newer Technology Praised

An accompanying commentary by Sean P. Donahue, MD, PhD, from Vanderbilt University School of Medicine in Nashville, Tennessee; and James B. Ruben, MD, from Northern California Permanente Medical Group in Roseville and University of California, Davis, commend the USPSTF recommendation for vision screening at least once for all children between the ages of 3 and 5 years.

"Newer technologies now allow the identification of amblyopia risk factors before strabismus and amblyopia develop and become entrenched, and evidence supports the effectiveness of treatment of children so identified," Drs. Donahue and Ruben write. "It should be emphasized that the I (inconclusive) rating given by the USPSTF for screening children younger than 3 years should not be misinterpreted as 'ineffective.'
We welcome the USPSTF level B recommendation for at least 1 vision screening in the child aged 3 to 5 years and believe that there is now adequate evidence to support an earlier screening using photorefraction or autorefraction in younger children."

Pediatrics. Published online January 31, 2011. Abstract

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