Fig. 2 Knockout lenses are more susceptible to opacification. Intact lenses were dissected from PKC knockout and control mice aged between 6- and 16-weeks old. The lenses were further incubated in serum-free DMEM medium at 37°C for 24 h. Transparent lenses were then treated with H₂O₂ or PBS for an additional 24 h at the indicated concentration of H₂O₂ (µmol l^-1). The extent of lens opacification was determined, photographs taken (A; 6-week-old representative lenses) and the data graphed (B). Six lenses from wild-type and PKC knockout mice treated with 0, 1, 5 and 10 µmol l^-1 H₂O₂ were photographed and digitized, and the transparency of the lenses is given as the contrast ratio ± s.e.m. (C). Data were analyzed using the paired Student's t-test. ^*P<0.01. Note: approximately equal, though mixed, ages were used for control and PKC knockout samples. Mixing of age groups was necessary as mice only had an average of two pups per litter and survival was poor.