From the 98 presentations of the XIIth Symposium on Colour Vision Deficiencies, 61 were selected after peer review and revision by the authors. In addition to these contributions this volume contains a cumulative index to all authors in the IRGCVD proceedings since the first one in 1968, including the present volume. The contents include contributions on basic questions of anatomical and electrophysiological organisation of the neural pathways underlying...