What is eye irritation?
The term eye irritation refers to feelings of dryness, itchiness, pain, or grittiness in the eye. Many factors can cause eye irritation, including injuries, dry eye, and infection, however, efficient product testing can ensure that exposure to the everyday products we use should not contribute to this.
Eye irritation is defined as the production of changes in the eye following the application of a test substance to the anterior surface of the eye, which are fully reversible within 21 days of application.
How has eye irritation been historically tested?
Historically the Draize test is synonymous with eye irritation testing. Draize eye irritation tests observe changes of cornea, conjunctiva, and iris in rabbit eyeballs following the exposure to test substances. This inhumane in vivo test sees a chemical applied on the cornea and conjunctival sac of one eyeball of a conscious rabbit while the other eyeball remains untreated for the negative and paired control and the rabbit is then euthanised following the test.
The development of in vitro methods has meant that the Draize test is now redundant, however it is still used across the world.
The animal-free eye irritation test
The Eye Irritation Test (EIT) is an OECD-approved (OECD TG 492) in vitro non-animal test method for identifying chemicals and mixtures that may be irritating to the corneal epithelium. The test method utilises an in vitro reconstructed human corneal epithelium (RhCE) model (EpiOcular™, MatTek Corp. or HCE, SkinEthic™), in an acute exposure assay to support international regulatory labelling requirements, according to the United Nations Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS). A wide variety of raw materials and formulations come into contact with the eyes, so this regulatory in vitro eye irritation test is ideal if you’re looking for simple Irritant or Non-Irritant classification. Many manufacturers use OECD TG 492 for the purposes of hazard identification and labelling for compliance with a range of legislation including EU REACH and the CLP Regulation. It is approved for chemicals not requiring classification and labelling for eye irritation or serious eye damage, but is NOT intended to differentiate between UN GHS Category 1 (serious eye damage) and UN GHS Category 2 (eye irritation).
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