Nutritional Strategies to Prevent Lens Cataract: Current Status and Future Strategies

Abstract

Oxidative stress and the subsequent oxidative damage to lens proteins is a known causative factor in the initiation and progression of cataract formation, the leading cause of blindness in the world today. Due to the role of oxidative damage in the etiology of cataract, antioxidants have been prompted as therapeutic options to delay and/or prevent disease progression. However, many exogenous antioxidant interventions have to date produced mixed results as anti-cataract therapies. The aim of this review is to critically evaluate the efficacy of a sample of dietary and topical antioxidant interventions in the light of our current understanding of lens structure and function. Situated in the eye behind the blood-eye barrier, the lens receives it nutrients and antioxidants from the aqueous and vitreous humors. Furthermore, being a relatively large avascular tissue the lens cannot rely of passive diffusion alone to deliver nutrients and antioxidants to the distinctly different metabolic regions of the lens. We instead propose that the lens utilizes a unique internal microcirculation system to actively deliver antioxidants to these different regions, and that selecting antioxidants that can utilize this system is the key to developing novel nutritional therapies to delay the onset and progression of lens cataract.

The ocular protective effects of PLGA nanoparticles loaded with lutein, in fat diet Wistar rats, treated with sistemic glucocorticoids

“…By MRI imaging, it was demonstrated that the lens has a unique internal microcirculation system to deliver antioxidants in different regions, and sodium is important in this mechanism [13]. In both groups treated only with Prednison, the serum level of ionic sodium was significantly increase (Tables 2 and 3).…”

“…It seems that steroids do not directly act on the lens but rather produce an imbalance of ocular cytokines and growth factors [12]. Recently, it was demonstrated that distinct metabolic compartments exist in the lens and these explains different etiologies of nuclear and cortical cataract, even the one induced by Prednison [13].…”

Vitamin C and the Lens: New Insights into Delaying the Onset of Cataract

“…However, with increasing age, GSH is known to decrease specifically in the lens nucleus [ 46 ], rendering proteins in this region susceptible to oxidative damage. Because of the proven association between lens cataract and oxidative damage, antioxidant supplementation has been promoted as a treatment strategy to slow down the progression of this type of cataract [ 6 , 7 , 8 ].…”

“…Given the protective effects of vitamin C in the lens and the link between a decrease in vitamin C with increasing age and with increasing cataract severity [ 11 ], it is not surprising that numerous studies exist investigating the relationship between vitamin C and the risk of cataract. While there a number of excellent in depth reviews on vitamin supplementation, diet, and cataract in human populations [ 7 , 8 , 81 , 82 , 83 , 84 , 85 ], reviews summarizing the findings from animal studies are lacking. However, these studies are important as they should be used to help inform and guide the design of human therapeutic studies.…”

“…It has been calculated that delaying the onset of cataract by 10 years would halve its incidence, and therefore reduce the need for, and cost associated with, cataract surgery [ 5 ]. Because of the proven association between lens cataract and oxidative damage, antioxidant supplementation has been promoted as a treatment strategy to slow the progression of cataract [ 6 , 7 , 8 ]. However, antioxidant supplementation has proven to be largely ineffective as an anti-cataract therapy.…”