Testability Study of the Titmus V3 Test in Pre-school Children

SIGNIFICANCE Vision screening can identify people who have vision problems requiring a comprehensive examination. When children are screened, the most prevalent serious problem is amblyopia secondary to uncorrected ametropia. Screening also identifies strabismus, which can lead to loss of binocularity. Early diagnosis permits treatment with restoration of balanced vision and binocularity. PURPOSE The study evaluated the testability of the Titmus V3 Vision Screener as a method to screen vision and strabismus in pre-school children. METHODS Pre-school children between 36 and 66 months of age underwent vision screening in six Michigan counties. The State of Michigan screening consists of the LEA Symbols test for visual acuity and the stereo butterfly for near-strabismus testing. The proposed Titmus V3 screening tests were the LEA Symbols slide for vision and near-strabismus test slide. Primary and secondary objectives of this study were to evaluate the percentage of pre-school children who completed the Titmus V3 screening tests for vision and near strabismus and factors associated with an inability to complete the tests, contrasting the pass/fail results between the state and Titmus V3 results. RESULTS Two-hundred sixty-Three children were tested. The percentages of children unable to score on the Titmus V3 instrument versus the state's LEA Symbols test were 16.0% and 5.3%, respectively. The percentage of children unable to score on the Titmus V3 near-strabismus test slide was 6.9 versus 3.4% on the State of Michigan stereo butterfly test. Younger age at testing was the most important factor associated with the inability to complete testing. CONCLUSIONS Because of testability limitations and higher failure rates relative to the State of Michigan testing methods, the Titmus V3 screening device is not a feasible alternative to the standard methods used by the State of Michigan for vision and near-strabismus screening among the pre-school subjects we tested.