Screen Validation

	Alaska Blind Child Discovery
	A cooperative, charitable research project to vision screen every preschool Alaskan
				Validation of Screening
Home	Screening tests are validated with the following statistics:				AAPOS 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 Ptosis ≤ 1 mm margin reflex distance Visual acuity: per age-appropriate standards* 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 operating 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.
ABCD History		Exam +		Exam -
Kids Eye Disorders	Screen +	A		B
Amblyopia	Screen -	C		D
Vision Screening	Screen ?	E		F
Issues			N=A+B+C+D
ABCD Clinics
References	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
Contact ABCD

abcd-textnav

Alaska Blind Child Discovery

Validation of Screening