Corrosive or Severe Irritant?

PorCORA - Porcine Cornea Reversibility Assay

PorCORA has been developed to differentiate between EU R36 and R41,
GHS Cat. I and II, and EPA Cat I and II.

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Alternative Assay Differentiates EU R36/R41, GHS Category I/II and EPA Category I/II


  • Recently, we developed the Porcine Corneal Opacity Reversibility Assay (PorCORA) assay, an alternative ocular irritation reversibility assay.
  • In a 32 compound validation, PorCORA correctly predicted ocular reversibility (88%), EU: R41 (91%), GHS: Category 1 (91%), and EPA: Category I (88%).
  • PorCORA measures corneal damage and recovery over a 21-day testing period using porcine corneas excised from waste abattoir eyes.
  • PorCORA is the only non-animal test system able to predict ocular hazard classifications and is currently undergoing regulatory consideration.

MB Research has been conducting in vivo ocular toxicology testing since 1972 and has conducted over 9,700 rabbit eye studies. We have pioneered ocular alternatives such as the Chorioallantoic Membrane Vascular Assay (CAMVA) and the Bovine Corneal Opacity & Permeability (BCOP) Assay and have conducted over 5,600 BCOPs since 1989.


Regulatory classification methods of ocular irritancy depend upon the time for an ocular injury to completely heal (EPA, 1997). The PorCORA assay utilizes cultured porcine corneas, normally discarded by abattoirs, to assess ocular irritancy and reversibility or healing potential. PorCORA was developed and validated to address this requirement without using live animals. PorCORA measures corneal damage and recovery over 21 days in cultured porcine corneas. Test materials are topically dosed on the corneal epithelium and assessed for damage by fluorescein stain retention, similarly to the Draize Rabbit Eye Test method. Damage to the tissue is visualized by the retention of fluorescein stain. Over 21 days, the tissue can be repeatedly stained with fluorescein to assess changes in the area of damage. Therefore, measuring the damaged corneal area that retains fluorescein in this ex vivo alternative model monitors recovery in ocular tissue. Because corneal damage is generally the most persistent of ocular injuries, the time course of the PorCORA represents a true reversible or non-reversible event. (Piehl et al., 2010) PorCORA was developed and validated by MB Research and was funded by two Society of Toxicology Colgate-Palmolive Alternative Research Grants.


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