Figure 1 is a diagram of the analytic framework and key questions from the original Systematic Evidence Review, Screening for Visual Impairment in Children Younger than Age 5 Years. The diagram includes the 8 key questions (KQ) of that review and a ninth —"Does screening for amblyopia and associated conditions in children younger than age 5 years lead to better vision outcomes?"—added to the 2003 update.
The diagram starts on the left with KQ 1—"What is the prevalence of visual impairment in children younger than age 5 years?"—and ends on the right at "health outcome."
One arrow proceeds from KQ 1 to KQ 7—"What are the adverse effects of screening?"—and stops. Another arrow proceeds from KQ1 to KQ 2—"Do reliable, accurate, and feasible screening tests exist that can be used to detect visual disorders in children younger than age 3 years or in children aged 3 to 5 years? These visual disorders include amblyopia, strabismus, refractive errors associated with amblyopia, other rarer conditions associated with amblyopia such as cataracts or ptosis, and refractive error not associated with amblyopia."
From there, the arrow continues to KQ 4—"Under what conditions is the treatment of amblyopia successful?"—and ends at "health outcome." Another arrow from KQ 4 points to "amblyopia." An arrow to KQ 4 comes from KQ 8—"What are the adverse effects of treatment?"
Three additional arrows fan out from KQ 1, proceeding to "strabismus," "refractive error associated with amblyopia," and "other factors associated with amblyopia." Then, the 3 arrows merge to 2 arrows. One goes to "amblyopia." The other goes to KQ 3—"Do detection and treatment of conditions associated with amblyopia before amblyopia has developed lead to better treatment outcomes (primary prevention)?"—and continues to "normal visual acuity." A dotted line continues from "normal visual acuity" to KQ 6—"Does improving vision result in improved health outcomes?"—and continues to "health outcome."
Another arrow proceeds from KQ 1 to KQ 9 and continues on to "normal visual acuity."
KQ 5—"Under what conditions is the treatment of refractive errors not associated with amblyopia successful?"—is not included in the diagram.