A system is described which permits rat lenses to be cultured and studied for periods in excess of 3 wk without loss of transparency or an increase in size. When galactose is added to the medium, the lenses undergo morphological changes comparable with those found in vivo with the eventual production of nuclear cataracts. Lenses cultured with the ciliary body attached are less likely to be injured during dissection and can be cultured as effectively as isolated lenses.