Same-chemical comparison of nonanimal eye irritation test methods: Bovine corneal opacity and permeability, EpiOcular™, isolated chicken eye, ocular Irritection®, OptiSafe™, and short time exposure.

The testing and classification of chemicals to determine adverse ocular effects are routinely conducted to ensure that materials are appropriately classified, labeled, and meet regulatory and safety guidelines. We have performed a same-chemical analysis using publicly available validation study results and compared the performance between tests for the same chemicals. To normalize for chemical selection, we matched chemicals tested by pairs of tests so that each matched set compared performance for the exact same chemicals. Same-chemical accuracy comparisons demonstrate a chemical selection effect that results in a wide range of overlapping false-positive (FP) rates and accuracies for all test methods. In addition, the analysis suggests that a tiered-testing strategy with specific combinations of tests can reduce the FP rate for some combinations. However, reductions in the FP rates were typically accompanied by an increase in the false-negative rates, resulting in minimal advantage in terms of accuracy. In addition, actual improvements in the FP rate after retesting positives with a second test are not as good as the theoretical improvements because some chemicals and functional groups appear to be broadly misclassified by all test methods, which, to the extent the tests make the same-chemical misclassifications, reduces the advantage of using tiered-testing strategies.