Nuclear cataract stems from the inexorable breakdown of long-lived macromolecules in the human lens. Although this realization is new, the overall framework is now quite clear. Racemisation, deamidation and truncation are the main drivers of protein denaturation and some amino acids are particularly susceptible to age-related decomposition. Understanding these processes leads to a conclusion that the prospects for reversing lens opacification are remote. Since age-related cataract appears to be inevitable, future strategies for slowing cataract formation may depend on a detailed examination of people who retain clear lenses into their eighth and ninth decades.