Tent photoscreening and patched HOTV visual acuity by school nurses: validation of the ASD-ABCD protocol. (Anchorage School District- Alaska Blind Child Discovery program)

Abstract

Background: Novel objective tests of risk factors for amblyopia offer an alternative for preschool vision screening. We compared the merits of photoscreening versus portable patched acuity testing in elementary schools. Photoscreening may outperform routine acuity testing in pediatric offices; however, both have fairly good validity when performed by specialists in preschool vision screening.

Methods: School nurses performed patched HOTV surround acuity testing and two types of photoscreening (MTI and Gateway DV-S20) in a portable tent near each classroom.

Results: 1700 children (696 1st grade, 710 Kindergarteners and 271 special-needs pre-Kindergarten). 14% had comprehensive exams and another 65% had normal photoscreens combined with patched acuities of 20/20 or better OU. We estimate the overall sensitivity/specificity using AAPOS guidelines for the modalities to be 39%:99% for patched HOTV acuity, 77%:99% for MTI photoscreening, and 85%:98% for Gateway photoscreening. The specificity of acuity testing was particularly low in pre-K due to 33% unable to complete the test, but about 80% of initial acuity failures were able to pass with pinhole.

Conclusion: Tent photoscreening in younger elementary school children was more sensitive and faster than patched acuity particularly in developmentally delayed pre-K children.