(A) Inter-tissue comparison of protein longevity showing numbers of proteins based on 14N-peptides only, 15N-peptides only, or 14N/15N ratios calculated (hatched pie). While in the lens a large number of protein had a greater proportion of 14N, other ocular tissues had a faster protein turnover with more proteins completely labeled with 15N within 12 weeks. (B) A list of the most abundant proteins that were only detected by 14N peptides with the absence of 15N. (C) Among the proteins identified with both 14N and 15N peptides—248, 362 and 398 proteins in the lens, the vitreoretinal and the sclera/choroid, respectively, the distribution of 14N-to-15N ratios of the lens proteins was different than those of the other tissues. As expected, the lens had the highest proportion of its 14N-proteins remaining. (D) The distribution of 14N/15N ratios from low to high as in Figure 2C. There is a long list of 278 proteins with only their 14N-proteins detected (dotted blue line to upper right), indicating possibly less 14N to 15N conversion of these proteins than those measured with 14N/15N ratios. Proteins that are implicated in cataract including structural proteins, gap junction and water channels, and metabolic enzymes are listed with arrows pointing to their corresponding values. The family of Crystallin proteins are listed below. Benchmark Histones H3.3 and H3.1/3.2 are also listed, representing transcription vs. cell proliferation activities, respectively.