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VIPS phase 1 and 2(1, 2) were monumental and important studies, but did not really address AAPOS guideline screening(3), but rather just a single pass- pre-K screening assuming no subsequent K and 1st grade screening.
I think it critical that AAPOS emphasize and encourage a series of age-appropriate tests rather than one single pre-K catch all screening. If you only had one opportunity to catch any amblyopia, you would need a SENSITIVE test.
Some amblyopia is manifest (i.e large angle constant strabismus or anterior cataract) but much is occult. By definition, the occult cases appeared normal to parents, to pediatricians, school nurses, etc.
The parent, the pediatrician and the overly busy pediatric ophthalmologist receiving vision screen referrals would much rather have a screen with high PPV (Positive Predictive Value) than one with high SENSITIVITY. The liability of the screen manufacturer or program thinks that it must have high sensitivity, but that still assumes a single screening. Series of age appropriate SPECIFIC objective migrating to sensory tests will have high sensitivity.
VIPS, by determining compared sensitivities for a pre-set (90% - 94%) specificity makes a case for mandated exams instead of single - preK screening. And for a disease (amblyopia) with just 4% prevalence, the 94% specificity is still too low.
I briefly comment, in the BVQ article(4) on Sean's and my experience compared, that our high PPV photoscreening programs did NOT find large numbers of missed amblyopes years after screening.
WHAT WE REALLY NEED FROM VIPS(1, 2), COMBINED WITH OTTAR'S(5) STUDIES, IT TO DETERMINE THE PREVALENCE OF ANISOMETROPIA OVER 1.5 DIOPTERS, HYPEROPIA OVER 3.5 DIOPTERS, ASTIGMATISM OVER 1.0 OBLIQUE OR 1.5 DIOPTERS, MYOPIA OVER 3 DIOPTERS, MANIFEST STRABISMUS IN A GROUP OF NON-ENHANCED PRE-K CHILDREN6.
If we had such populations estimates, then validation studies of existing and future screening could be done much more cheaply and quickly on real screening experiences with follow up on mainly referred cases. Robert W. Arnold, MD July 2006

1. VIPS. Comparison of preschool vision screening tests as administered by licensed eye care professionals in the vision in preschoolers study. Ophthalmology. Apr 2004;111(4):637-650.
2. VIPS, Dobson V, Quinn G, et al. Preschool vision screening tests administered by nurse screeners compared with lay screeners in the Vision in Preschoolers Study. IOVS. 2005 2005;46:2639-2648.
3. Swanson J. Eye examination in infants, children and young adults by pediatricians: AAP Policy Statement. Ophthalmology. 2003;110(4):860-865.
4. Arnold RW, Donahue SP. The yield and challenges of charitable state-wide photoscreening. Binocul Vis Strabismus Q. 2006;21(2):93-100.
5. Ottar WL, Scott WE, Holgado SI. Photoscreening for amblyogenic factors. J Pediatr Ophthalmol Strabismus. 1995;32:289-295.
6. 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):314-316.

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