OECD 437: BCOP (bovine corneal opacity permeability)

OECD 437: The Bovine Corneal Opacity and Permeability (BCOP) Assay is an in vitro method originally described in 1992 to predict the in vivo ocular irritation potential of a test chemical using living bovine corneal tissue. Types of injury caused by exposure to the chemical are quantitatively assessed by changes in corneal opacity using an opacitometer and permeability using a visible light spectrophotometer. Changes in opacity are determined by measuring the amount of light transmitted through the cornea, and changes in permeability are measured by the amount of fluorescein dye that penetrates through the cornea. 

Both measurements are used to calculate an in vitro irritancy score (IVIS) to assign an in vitro irritancy hazard classification category for prediction of the in vivo ocular irritation potential of a test chemical. 

Information about corneal opacity and permeability give further insights into the mechanism of damage, e.g. opacity damage can be caused by protein denaturation or the induction of stromal swelling.