I shall not reiterate by synthesizing the syntheses; indeed, these have shown us how much progress has been made. At the same time, we have seen that certain questions remain unanswered. The objective of the 4th Symposium has thus been attained: as with the preceding symposia, we aimed to determine the current state of knowledge and the main directions future research should adopt. The conclusions of the scientific congress have taught me that our understanding of the process which regulates sight and its evolution is beginning to improve, that much has yet to be done, but that work in this area abounds in exciting prospects, and is definitely advancing. The workshops have taught me that, apart from problems related to products and their development, there is a real concern for training, information and documentation — in short, for communication.