Our knowledge on the mechanism of amblyopia has gained in recent years from concerted research efforts in basic science and clinical laboratories. Different clinical forms of amblyopia are reviewed and their diagnostic and therapeutic significance discussed. In spite of etiologic differences there are pathophysiological similarities. The value of the time proven constant occlusion treatment of the sound eye remains unchallenged even though minor modifications have become necessary to prevent occlusion amblyopia in infants and young children. Part-time occlusion and penalization are of ancillary value but cannot be considered equal in effectiveness to constant occlusion. Due to increasing public awareness there is a trend toward earlier diagnosis and thus successful treatment of amblyopia. However, more efforts must be directed toward including newborns in visual screening examinations.