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Alaska Blind Child Discovery

A cooperative, charitable research project to vision screen every preschool Alaskan

Validation of Screening

Screening tests are validated with the following statistics:

2021 AAPOS Uniform Guidelines | 2013 AAPOS .

AAPOS 2003 Guidelines for Pre-School Vision Screen Studies:

Amblyogenic factors to be detected by screening:
Anisometropia (spherical of cylindrical) > 1.5 D
Any manifest strabismus
Hyperopia > 3.5 D in any meridian
Myopia magnitude > 3.0 D in any meridian
Any media opacity > 1 mm in size
Astigmatism > 1.5 D at 90° or 180°
Astigmatism > 1.0 D in oblique axis (10degrees)
Ptosis ≤ 1 mm margin reflex distance
Visual acuity: per age-appropriate standards*

Prevalence of these Risk Factors

Report sensitivity, specificity and confidence intervals for each
Results reported for children ≤ 42 months; report older separately
Report proportion unable to complete, and those inconclusive
Ideally report Receiver operater characteristic curves (ROC)
*AAP / AAO / AAPOS Age standards: age 3-5 years less than 20/40 | age 6 and older less than 20/30 or two line difference.
D = diopters, oblique axis = (>10° eccentric to 90° or 180°), margin reflex distance = distance from corneal light reflex to upper lid margin.

Donahue S, Arnold R, Ruben JB. Preschool vision screening: What should we be detecting and how should we report it? Uniform guidelines for reporting results from studies of preschool vision screening. J AAPOS. 2003;7(5):314-315.

Photoscreening Flowchart (JPOS 51:46-52, 2014)

ABCD introduction to Validation (2017) (2021)

ABCD Excel Validation grid (download)

ABCD 2021 Validation Assistant (Excel template)

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Sensitivity A/(A+C)
Specificity D/(D+B)
Positive Predictive Value A/(A+B)
Negative Predictive Value D/(C+D)
Prescreening Probability (A+C)/N
ABCD sensitivity A/(A+C+E+F)
ABCD specificity D/(D+B+E+F)

Alaska Med 45(3):34-45

ir-Sens (A+E+F)/(A+C+E+F)

irSpec (D)/(D+B+E+F)

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JPOS 51:46-52 2014
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