Minister, Mr. Mayor, Mr. Honourary President, Honoured guests, Ladies and gentlemen, Dear colleagues and friends: On behalf of the Ophthalmological Society of the German Democratic Republic I welcome you to this symposium. I am glad to see so many experts from more than 20 countries of all parts of the world assembled here in Schwerin, who have travelled far and overcome many obstacles in doing so. I wish to extend a special welcome to the Vice-Minister of Health of the GDR, whom we should like to thank for the continuing generous support of the government of the GDR for this event. It is a great pleasure to welcome scientists from socialist countries such as the Soviet union, Poland, Cechoslovakia, Hungary, Bulgaria and Yugoslavia and from non socialist countries such as USA, Canada, Great Britain, The Netherlands, Belgium, France, Federal Republic of Germany, Austria, Sweden, Finland, Denmark, Italy, Spain, Switzerland and far away Japan and Australia. I have the great honour to welcome Prof. FRANQOIS as our Honourary President, our scientific directors Prof. VOLKOV from Leningrad and Prof. BLODI from Iowa City, and Dr. ZIMMERMAN and other members of the Verhoeff Society, and Prof. GAILLOUD and Prof. MEYER-SCHWIcKERATH as prominent representatives of the Club Jules Gonin. We are delighted that you have accepted our invitation.