Comparing a traditional single optotype visual acuity test with a computer-based visual acuity test for childhood amblyopia vision screening: a pilot study.

OBJECTIVE

To investigate the effectiveness of a traditional flip-chart optotype test, the Sheridan Gardiner test (SGT), in measuring visual acuity and detecting amblyopia, compared with a free, computer-based test (CBT), LazyeyeTest.org.

DESIGN

Prospective, masked, cross-over study.

PARTICIPANTS

Seventy kindergarten-aged children from a downtown Toronto elementary school enrolled in the Kids2See vision screening program.

METHODS

Visual acuity in the children was measured monocularly using both tests. The visual acuity results, number of referrals, and outcomes of referrals were compared, as was the usability from the perspective of the child and the vision screener.

RESULTS

The children were more likely to score low visual acuity values with the CBT, a result predicted by the existence of crowding bars on the CBT's optotypes. The CBT referred an extra 5 children than the SGT, and of the 4 who saw an ophthalmologist 2 had amblyopia. The SGT referred one child not referred by the CBT. The Cohen's kappa coefficient was 0.67 and the difference in referral rates was not significant (p = 0.13). Relative to the SGT, the sensitivity of the CBT was 88%, specificity was 92%, positive predictive value was 58%, and negative predictive value was 98%. The CBT appeared to be easier and more efficient to administer, more stimulating, and was preferred by the children.

CONCLUSIONS

Replacing the SGT with LazyeyeTest.org would increase the efficiency and likely the sensitivity of amblyopia screening. Further research is warranted to confirm the outcomes and to determine if the CBT can be administered accurately by lay screeners.