Cataract is responsible for the blindness of over 20 million people worldwide. Though operative treatment is possible, the need far outstrips current surgical capacity - less than one in five will be able to have surgery. Why cataract occurs, how frequently it occurs, and how its onset or progress might be checked are among the questions dealt with in this volume. This publication contains papers presented at the 4th International Cataract Epidemiology Meeting held in Melbourne, Australia. The great variety of interesting material included reflects the wide range of interests of clinicians and researchers in this fascinating field. The volume concentrates on cataract pathogenesis and includes current methods for the classification of cataracts, study guidelines and the results of epidemiological studies. It is important reading for ophthalmologists and epidemiologists concerned with cataract.