Long-chain and very long-chain polyunsaturated fatty acids in ocular aging and age-related macular degeneration

Retinal long-chain PUFAs (LC-PUFAs, C₁₂-C₂₂) play important roles in normal human retinal function and visual development, and some epidemiological studies of LC-PUFA intake suggest a protective role against the incidence of advanced age-related macular degeneration (AMD). On the other hand, retinal very long-chain PUFAs (VLC-PUFAs, C_n>22) have received much less attention since their identification decades ago, due to their minor abundance and more difficult assays, but recent discoveries that defects in VLC-PUFA synthetic enzymes are associated with rare forms of inherited macular degenerations have refocused attention on their potential roles in retinal health and disease. We thus developed improved GC-MS methods to detect LC-PUFAs and VLC-PUFAs, and we then applied them to the study of their changes in ocular aging and AMD. With ocular aging, some VLC-PUFAs in retina and retinal pigment epithelium (RPE)/choroid peaked in middle age. Compared with age-matched normal donors, docosahexaenoic acid, adrenic acid, and some VLC-PUFAs in AMD retina and RPE/choroid were significantly decreased, whereas the ratio of n-6/n-3 PUFAs was significantly increased. All these findings suggest that deficiency of LC-PUFAs and VLC-PUFAs, and/or an imbalance of n-6/n-3 PUFAs, may be involved in AMD pathology.