Bovine Corneal Opacity and Permeability

Commonly used acronym: BCOP

Scope of the method

Alternative method relates to
  • Human health
Alternative method is situated in
  • Regulatory use - Routine production
Type of alternative method
  • In vitro - Ex vivo
This method makes use of
  • Animal derived cells / tissues / organs


Method keywords
  • serious eye damage
  • no classification for eye irritation or serious eyedamage
  • eye irritation
  • corneal opacity
  • Permeability
  • isolatedcornea
  • Bovine
Scientific area keywords
  • Toxicity and other safety testing including pharmacology
Method desription

The Bovine Corneal Opacity and Permeability test method (BCOP) is an in vitro test method that can be used to identify chemicals (substances or mixtures) as either 1) causing “serious eye damage” (category 1 of the Globally Harmonised System for the Classification and Labelling of chemicals (GHS)), or 2) not requiring classification for eye irritation or serious eye damage according to the GHS. The BCOP uses isolated corneas from the eyes of cattle slaughtered for commercial purposes, thus avoiding the use of laboratory animals. Each treatment group (test chemical, negative/positive controls) consists of a minimum of three eyes where the cornea has been excised and mounted to a holder. Depending on the physical nature and chemical characteristics of the test chemical, different methods can be used for its application since the critical factor is ensuring that the test chemical adequately covers the epithelial surface. Toxic effects to the cornea are measured as opacity and permeability, which when combined gives an In Vitro Irritancy Score (IVIS) for each treatment group. With the OP-KIT, a chemical that induces an IVIS ≥ 55.1 is defined as a category 1 (“causing serious eye damage” according to the GHS); a chemical that induces an IVIS≤ 3 is considered as not requiring classification for eye irritation or serious eye damage according to the GHS. This is according OECD TG 437. Currently efforts are made to replace the OP-KIT with LLBO, validation is ongoing for incorporation in OECD 437

Lab equipment

OP-KIT or LLBO (laser light based opacitometer) and spectrophotometer

Method status
  • Validated by an external party (e.g. OECD, EURL ECVAM,…)

Pros, cons & Future potential


+ in vitro method, fast results,


- access required of bovine eyes , testing faciltiy need to close to the slaughterhouse, hands-on assay

Future & Other applications

Yes the current equipment to measure opacitiy is the OP-KIT, but is not anymore available since approx 10 years. We hope to add the LLBO as equipment.

References, associated documents and other information


- OECD 437, 9 October 2017

Associated documents

Contact person

Mieke Van Mulders


Chemical and physical health risks