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The Waterloo Differential Acuity Test (WatDAT)-Testability and normative data
S Aryal1, E L Irving1, L W Christian1
1School of Optometry and Vision Science, University of Waterloo, Waterloo, Ontario, Canada.
Purpose:
To investigate the testability of the WatDAT for measuring recognition visual acuity (VA) in children aged between 18 to 48 months, report preliminary age-related data and compare with two commercially available matching tests.
Methods:
A total of 57 children (18.5-45.8 months) attended for two sessions. Forty-six children were placed in a typical group and 11 were classified as atypical if general or ocular health history or prematurity was reported. Binocular and monocular VA was attempted with WatDAT House/Circle (HC) and WatDAT Faces. Binocular VA was attempted with Kay Pictures and Patti Pics. The percentage able to complete each test (testability) and the corresponding VA are reported.
Results:
The percentage of typical children able to complete binocular testing with the WatDAT HC, WatDAT Faces, Patti Pics and Kay Pictures was 96%, 86%, 75% and 80%, respectively. More children were testable with the binocular WatDAT HC compared to the Patti Pics and with WatDAT HC compared to Kay Pictures (p = 0.03). Monocularly, 56% and 54%, respectively, were testable with WatDAT HC and WatDAT Faces for both eyes. VA improved with age for all measures. Repeated measures ANOVA indicated that there was no significant difference between binocular VA with WatDAT HC and WatDAT Faces (p = 0.07), but there was a significant difference between the other tests. Both WatDAT tests gave poorer VA than the Patti Pics or Kay Pictures, while the Patti Pics gave poorer VA than Kay Pictures. Of the atypical children, 82% completed both the WatDAT HC and WatDAT Faces binocularly.
Conclusions:
WatDAT HC had good testability, comparable or better than testability for other tests for younger age groups as reported in the literature. Additionally, the results indicate higher testability with the WatDAT HC compared to Patti Pics matching and Kay Pictures. VA improved with age from 18 to 47 months.
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