When I think about the history of eye irritation testing, I can’t help but reflect on how far we’ve come. The Draize rabbit eye test was developed back in 1944, in the aftermath of coal tar mascara causing blindness in consumers. The FDA needed a way to screen products for safety, and rabbits seemed like the obvious choice at the time: they had large eyes, they were easy to handle, and they couldn’t cry out the test substances because they lack tear ducts. That last point, while “convenient” for testing purposes, meant that rabbits’ eyes were exposed to potentially harmful chemicals for far longer than human eyes would be.
For 80 years, this test has been used millions of times worldwide. Chemicals were applied directly to the eyes of conscious, restrained rabbits, causing redness, swelling, ulceration, sometimes even blindness. The animals were observed for days or weeks, their suffering scored on a subjective scale by researchers peering at their eyes with penlights. And here’s the thing that always struck me as particularly troubling: the test was never properly validated. Multiple studies showed wildly different results between laboratories testing the same substances [1]. The anatomical differences between rabbit and human eyes meant the data didn’t translate reliably to human safety anyway.
Yet for decades, when advocates pushed for alternatives, they were told the test was necessary. Science hadn’t caught up yet.
What about now?
Today, we have reconstructed human cornea-like epithelium grown from human cells. We have sophisticated 3D tissue models that actually replicate human eye physiology better than a rabbit ever could. We have validated, regulatory-approved methods that are more consistent, more predictive of human response, and cause zero suffering. The science has absolutely caught up.
This is why we’re genuinely excited to announce that XCellR8 can now offer OECD Test Guideline 492B, the most advanced eye irritation test available for regulatory purposes. And this isn’t just another incremental improvement. This is the first single non-animal test method that can distinguish between all three UN GHS categories on its own: Category 1 (serious irreversible eye damage), Category 2 (reversible eye irritation), and No Category (no classification needed).
Previously, identifying Category 2 irritants required a weight-of-evidence approach, combining multiple test methods. TG492B changes that. It’s a stand-alone test that can fully replace the Draize test for classification purposes. For the first time, regulatory testing for eye hazard identification can be done entirely without animals, with a single, validated human-relevant method.
The test uses reconstructed human cornea-like epithelium that closely mimics the biochemical and physiological properties of the actual human corneal epithelium. Test substances are applied directly to the tissue surface, just as they might contact a real human eye, and cell viability is measured using the MTT assay. Different exposure times allow the method to distinguish between the three categories of ocular hazard, providing regulators with the classification data they need while giving us results that are actually relevant to human safety.
A long time coming
It’s worth remembering that the Draize test was developed with humanitarian intentions, trying to prevent the kind of injuries that had already happened to consumers. But intentions matter less than outcomes. For 80 years, we’ve subjected millions of rabbits to a test that was scientifically flawed from the start, when we could have been investing in human-relevant alternatives all along.
The adoption of TG492B by the OECD in 2022 represents a watershed moment. It’s recommended as a full replacement for the in vivo Draize test. Not a refinement. Not a reduction. A replacement. That’s the word that matters.
For XCellR8, being able to offer this test means we can support companies who want to ensure their products are safe for human use, using methods that are both more scientifically robust and completely free from animal suffering. It’s exactly the kind of science we built this laboratory to provide: cutting-edge, human-relevant, and aligned with both regulatory requirements and ethical values.
If you’re working in cosmetics, personal care, household products or the chemical industry, and need eye irritation testing for either regulatory or screening purposes, get in touch with us at info@x-cellr8.com. Let’s talk about how TG492B can support your product development and regulatory submissions without the use of any animals or animal-derived test components.
Sources:
[1] Weil, C. S., Scala, R. A. (1971). Study of intra- and inter-laboratory variability in the results of rabbit eye and skin irritation tests. Toxicology and Applied Pharmacology, 19(2), 276-360.
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