A2E levels are significantly increased in the absence of ABCA4. Total A2E levels were measured from eyecups harvested at P30, 60 or 120. 3–6 independent samples were measured for each group and values are presented as mean pmoles of A2E/eye±SEM. Rearing under 300 lx did not have a significant effect on A2E accumulation but at every timepoint, in both the WT and Nrl−/− background, animals lacking ABCA4 accumulated significantly more A2E than control animals. *p<0.05, **p<0.01, ***p<0.001.