title: Alternative methods for ocular toxicology testing: validation, applications and troubleshooting.
abstract: BACKGROUND
  Humanitarian concern, scientific progress and legislative action have lead to the development, validation and regulatory acceptance of alternative in vitro ocular models. However, to date not a single in vitro alternative ocular toxicity test has been validated as a full replacement for the in vivo Draize rabbit eye test for all classes of chemicals across whole irritancy ranges. Since the 1990s, ocular alternative methods have been validated but few have been accepted for regulatory purposes. These assays include: organotypic models, such as the bovine corneal opacity and permeability (BCOP) assay, the isolated chicken eye (ICE) test method and cell function-based in vitro assays, such as the cytosensor microphysiometer (CM) and the fluorescein leakage (FL) test methods. Some refinements to in vivo testing methods have been accepted by regulatory agencies, including humane endpoints to avoid or minimize pain and distress.
  
  
  METHODS
  The authors provide a review of the background, protocol overview, applications and their validation status of the tier-testing approach. Furthermore, the authors provide expert analysis and provide their perspective on this approach and potential future developments.
  
  
  CONCLUSIONS
  In the search for a battery of methods that replaces the in vivo Draize test, it is necessary to prioritize techniques, define related mechanisms and justify statistical approaches. Overall, only when the reliability and relevance of a method is unequivocally supported will any technique be ready for regulatory acceptance.
authors.affiliation: St. John's University, College of Pharmacy and Health Sciences, Toxicology Division, Department of Pharmaceutical Sciences, Queens, NY 11439, USA.
authors.forename: Sanjay L
authors.initials: SL
authors.lastname: Dholakiya
authors.forename: Frank A
authors.initials: FA
authors.lastname: Barile
mesh_terms: D000826:Animal Testing Alternatives / Q000379:methods*; D000818:Animals; D002417:Cattle; D002645:Chickens; D023381:Endpoint Determination; D005123:Eye / Q000187:drug effects / Q000473:pathology; D005128:Eye Diseases / Q000139:chemically induced* / Q000473:pathology; D006801:Humans; D011817:Rabbits; D015203:Reproducibility of Results; D018675:Toxicity Tests / Q000379:methods*; D014116:Toxicology / Q000379:methods; D054928:Validation Studies as Topic