Metabolic Considerations Regarding Age-related Macular Degeneration (AMD):A Focus on Current Knowledge Effects of Caloric Restriction (CR): A Review

In Western countries, AMD (Age-Related Macular Degeneration) is the leading cause of blindness in individuals over the age of 55. AMD is one of the most severe pathologies affecting the eye; in fact it damages the macula causing a serious impairment of the central vision. There are two forms of AMD: early or dry AMD and advanced AMD, which can occur as an atrophic form (geographical atrophy) or as a wet or exudative (neovascular) form (10%-15% of cases), less frequent but more disabling. Many studies on mouse models have shown that caloric restriction (CR) decreases age-related decline of ocular functions by reducing oxidative stress. It is therefore potentially useful in modulating the endophenotype of individual AMD patients This type of intervention could also be effective in humans, but being not easily applicable, it has not yet been studied extensively in the clinical setting. However, it is now known that CR mimetics can have similar benefits as CR. To allow for the wide application of the benefits of CR in the clinical setting, mimetic compounds will be developed including the activators of sirtuins and adenosine monophosphateactivated protein kinase (AMPK). Even the ketogenic diet seems to have a protective role on retinal neurodegeneration, but the data supporting this notion in the literature are still few. Finally, the role of the low glycemic index diet should not be underestimated. Extensive studies on a large population of patients must be conducted to demonstrate the effectiveness of CR, CR mimetics, ketogenic diet or simply reduction of the glycemic index of the diet on the AMD prevention and/or progression.