Ophthalmic toxicology is a specialist area that deals with potentially adverse effects on the eye from chemicals and their metabolites, reaching the eye by local contact and from the systemic circulation, and also covers the effects that may be produced systemically by chemicals that have been absorbed into the circulation following topical contact with the eye. This chapter reviews, with illustrative examples, all these aspects of ophthalmic toxicology, with particular reference to causation, mechanisms of production of lesions, relevant
in vivo
and
in vitro
laboratory testing procedures, the significance and clinical relevance of the observed effects. Site‐specific lesions and functional disturbances in the eye that are discussed in detail are those to the cornea, iris, ciliary body, aqueous humour production, the lens, retina, optic nerve and extraocular muscles. Systemic effects following topical contamination of the eye are discussed particularly for chemicals and drugs, and discussed in terms of the sites of absorption.