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Negative predictive value of a population-based preschool vision screening program
I De Becker1, H J MacPherson, G R LaRoche
1Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada.
Insights
The Enhanced Vision Screening Program effectively identifies vision problems in children, with a high negative predictive value of 97.6%. However, it
Area of Science:
- Ophthalmology
- Pediatric Vision Care
- Public Health Screening
Background:
- The Enhanced Vision Screening Program is a population-based initiative examining children for amblyopia, strabismus, and high refractive errors.
- The program screens an average of 11,910 children aged 4.5 to 5.5 years annually.
- To date, 59,782 children have been examined.
Purpose of the Study:
- To determine the negative predictive value (NPV) of the Enhanced Vision Screening Program.
- To assess the probability that a child who passes the screening test does not have amblyopia, strabismus, or high refractive errors.
Main Methods:
- A total of 11,734 children passed the initial vision screening.
- 200 of these children were randomly selected for a gold standard examination.
- Examinations were conducted by an orthoptist and an ophthalmologist.
Main Results:
- 157 out of 200 selected children completed the gold standard evaluation.
- The overall NPV for any potentially vision-threatening ocular condition was 97.6%.
- The NPV for visually significant conditions targeted by the screening was 98.7%.
Conclusions:
- The screening program's NPV is not 100%, meaning some cases of amblyopia, strabismus, or refractive errors may be missed.
- Rare, potentially vision-threatening conditions might also go undetected.
- Parents should be informed about the screening's limitations when results are shared.
Background:
The Enhanced Vision Screening Program is a population-based vision screening program that has, at present, examined 59,782 children. Its main goal is to detect amblyopia, strabismus, and high refractive errors. An average of 11,910 4 1/2- to 5 1/2-year-old children are screened yearly. The current study determines the negative predictive value of the screening program: For a subject having passed the vision screening test, what is the probability of not having amblyopia, strabismus, or high refractive errors?
Methods:
Of the 11,734 subjects who passed the vision screening, 200 were randomly chosen to undergo a strictly defined gold standard examination by an orthoptist and an ophthalmologist.
Results:
Of the 200 randomly chosen subjects, 157 underwent the gold standard evaluation. The negative predictive value of the Enhanced Vision Screening Program was 97.6% for any potentially vision-threatening ocular condition. It was 98.7% if we considered only the visually significant ocular problems that the test was designed to detect.
Conclusion:
Because the negative predictive value of the Enhanced Vision Screening Program is not 100%, some children with amblyopia, strabismus, or refractive errors are missed. Occasionally, a rare, potentially vision-threatening condition may go undetected. Parents should be made aware of this when they receive the results of the vision screening.