On behalf of the editorial board and the organizing committee of the 4th congress of the International Society of Ocular Toxicology (I SOT), held in AnnecyNeyrier du Lac, France, October 9 -13, 1994, we are pleased to present to the ocular toxicology community this indexed volume of our congress proceedings. The 4th congress was designed primarily to facilitate and update the knowledge in ocular electrophysiology and ocular pharmacokinetics, in both the clinical and preclinical aspects. The outcome of this 4th congress, established in this volume, is a useful contribution to the meth­ odology in both fields and will hopefully assist in the evaluation and interpretation of ocular findings recorded in animal studies on drugs and other chemicals, in order to protect human health. Undoubtedly, work on the mechanisms of ocular toxicology in the process of pharmaceutical development must continue and these proceedings, embodying the presented papers, will add to the data base. The editors, the congress organizing committee and the members of the International Society of Ocular Toxicology thank the speakers who gave their time, knowledge, and expertise to assist us in this project. The following manuscripts contain the main substance of each of the platform presentations and, in some cases, much more. Moreover, our thanks go to all the participants coming from a range of background- regulatory, academic and industrial -for their attention and excellent contributions during the discussion.