Preschool Worth 4-Shape test: testability, reliability, and validity.
OBJECTIVE
The Worth 4-Dot is used to assess binocular fusion, but it is difficult to use with young children. We modified the Worth 4-Dot by replacing the circles with shapes while maintaining the same color configuration. The purpose of this study was to determine the testability, reliability, and validity of the Worth 4-Shape test.


METHODS
Subjects aged 2 to 8 years and 4 patients aged over 8 years with best-corrected visual acuity of 20/40 or greater (n = 131 patients, n = 123 normals) attempted test and retest at 35 cm and 3m using the Worth 4-Shape and Worth 4-Dot. To provide a gold standard, medical history, bifoveal fixation, and stereoacuity were reviewed.


RESULTS
Testability of the Worth 4-Shape was significantly higher than the Worth 4-Dot both in children aged less than 4 years (95.9% vs 79.5% at 35 cm, P <.001; 79.5% vs 55.1% at 3 m, P <.001) and older than 4 years (98.5% vs 88.6% at 35 cm, P <.001; 90.9% vs 82.4% at 3m, P =.04). Test-retest analysis found comparable concordance for the Worth 4-Shape and Worth 4-Dot tests (P >.3). The sensitivity and specificity of the Worth 4-Shape (92%, 97%) and Worth 4-Dot (90%, 94%) were comparable. Between-test analysis found 96% agreement between both tests at 35 cm and 97% agreement at 3m.


CONCLUSIONS
The success rate for the Worth 4-Shape is higher than the Worth 4-Dot, especially in children aged less than 4 years, and has equivalent accuracy. The Worth 4-Shape test-retest reliability is high supporting its validity for use with young children.
Morale
Sarah E
SE
Retina Foundation of the SW, Dallas, Texas 75231, USA.
Jeffrey
Brett G
BG
Fawcett
Sherry L
SL
Stager
David R
DR
Salomão
Solange R
SR
Berezovsky
Adriana
A
Lapa
M Cecilia
MC
Birch
Eileen E
EE
D002648:Child; D002675:Child, Preschool; D003867:Depth Perception; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014786:Vision Disorders / Q000175:diagnosis*; D014787:Vision Tests / Q000592:standards*; D015348:Vision, Binocular; D014792:Visual Acuity