Teller II and Cardiff Acuity testing in a school-age deafblind population

To compare Teller Acuity Cards II (TAC II) and Cardiff Acuity Test (CAT) acuities, test-retest reliability and testability in children with visual, auditory, motor and cognitive impairments.

Twenty-one children designated as "Deafblind" were tested under binocular conditions. Visual acuity was measured with both the TAC II and CAT in two sessions, with test order randomized and counterbalanced between sessions. Visual acuity, examiner confidence in the acuity result (3 point scale), testing time, and level of motor impairment (3 point scale) were recorded. Information about visual and auditory function and ocular and medical diagnoses were obtained by record review.

The success rate was high (95%) and test time similar (p = 0.267) for both tests (TAC II, 204 +/- 111 s; CAT, 222 +/- 111 s). Mean LogMAR acuities were not significantly different (TAC II, 0.82 +/- 0.47; CAT, 0.72 +/- 0.47; p = 0.068). The 95% limits of agreement for LogMAR test-retest differences were +/-0.60 for TAC II and +/-0.70 for the CAT and there was a trend for increased variability with poorer acuity for the CAT test only.

The TAC II and CAT give similar estimates of acuity, test-retest reliability, and testing time in this small population of "Deafblind" children. Future studies should be designed to explore whether these results are consistent in subpopulations, such as Deafblind children with very poor vision and/or significant motor impairment. Moreover, additional study is necessary to evaluate the effect of patient characteristics on the examiner's ability to make threshold acuity judgements.