SummaryThis review summarizes current knowledge concerning cataract formation. Metabolically induced forms of cataract are discussed, but mainly aspects of cataract formation in older patients are described, especially with respect to lens protein modifications and epidemiological results. In most cases, cataract in older people is a multifactorial process and therefore cataracts appear in a multitude of different morphological types. Only accurate documentation of lens disturbances and the use of reproducible methods can provide more detailed information about the complexity of the disease cataract.