In this review the authors first give an overview of the general strategies of mapping which differ whether the biochemical (molecular) defect of the disease is known or not. The main problems besides mapping are concerned for the first category with the correlation between mutation and phenotype and for the second, with heterogeneity, genetic vs phenotypic. Finally, tables are displayed of eye diseases or diseases with eye involvement (metabolic or not) which have been currently mapped, as well as candidate genes actually or putatively involved in visual transduction.