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The Effect of Preschool Vision Screening 2.5.1

The Necessity of High Participation Rates

The participation frequency of a screening program is crucial for its effectiveness. This was shown by Williams et al. [51] in a study on prevalence of amblyopia in 7.5 year old children with and without screening at 37 months. When comparing those who actually attending screened with those who were not screened, there was a small, but statistically significant difference in outcome. Comparing those offered screening (67% actually participated) with those not offered screening, this difference disappeared. This points to the need for high attendance rates in order for a screening system to be effective and worthwhile from a population point of view, which was addressed in the editorial by Moseley and Fielder in the same issue. In Sweden, where 99 % of 4- to 5-year-olds participate in vision screening, deep amblyopia (visual acu

Summary for the Clinician

Fig. 2.2. Suggested flowchart for evaluating preschool vision screening programs

Fig. 2.2. Suggested flowchart for evaluating preschool vision screening programs ity <0.3) has been shown to decrease to a tenth of that in unscreened age groups [28].

The best way to reach acceptable participation frequencies for vision screening programs is probably to incorporate the program into an already existing system with a high participa tion rate, e.g., vaccination programs or school entry. The vision screening system in Sweden is one part of the 4-year check-up at the Child Health Care centers, with retesting of inconclusive and borderline cases.

Fig. 2.3. a The age at which strabismus is diagnosed by an ophthalmologist at the Eye Clinic in the city of Vasteris, Sweden, for all children born 1979-1980. Note that only 22% (16/72) is detected at preschool vision screening (red bars). (Reprinted from Sjostrand and Abrahamsson [44] with kind permission of Georg Thieme Verlag.) b The age at which amblyopia (visual acuity <0.5) is diagnosed by an ophthalmologist at the Eye Clinic in the city of Vasteris, Sweden, for all children born 1979-1980. Slightly less than half of children with amblyopia (30/64) are detected at preschool vision screening (red bars). (Reprinted from Sjostrand and Abrahamsson [44] with kind permission of Georg Thieme Verlag)

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