Genetic approach of antioxidant vitamin supplementation for glaucoma neurodegeneration

Abstract

AbstractGlaucoma is one of the main causes of irreversible blindness, producing 12.3% of blindness worldwide.According to data from the American Academy of Ophthalmology, it is estimated that there are about 4.5 million people with glaucoma in the world. However, the real number should be much higher if we consider that in developed countries there are 50% of people with undiagnosed glaucoma. And in developing countries, this percentage rises to 90%.Glaucoma is an age‐related disease. Its prevalence in the population over 40 years is around 2%. And in people over 70 years, the prevalence is between 3 and 8 times higher. Taking into account the progressive aging of the population, it is expected that the number of people affected by this disease will continue to increase in the coming years.Among all types of glaucoma, primary open‐angle (POAG) is the most common, accounting for 60–70% of all cases. This type of glaucoma is characterized by high intraocular pressure, optic nerve atrophy and progressive visual field loss.It is a multifactorial disease determined by both genetic and environmental factors. The cause still remains unknown. So, efforts are focused on preventing blindness through early diagnosis and hypotensive treatment, which is not always effective. Currently, neuroprotective treatment is also considered.One of the most studied processes in relation to optic nerve degeneration in glaucoma is oxidative stress. Many studies demonstrate the association between the increase in pro‐oxidant molecules and the progression of POAG. Other studies show how nutritional supplementation with antioxidant vitamins decreases the risk of glaucoma and slows down its progression.The genetics of glaucoma and its interaction with nutritional compounds have also been studied. Thus, it has been shown in patients with POAG that those who have a certain polymorphism of a vitamin C transporter gene have a significantly lower amount of this vitamin. The same as POAG patients carrying a specific polymorphism in a vitamin E transporter gene, who have significantly lower levels of this vitamin.Another study has identified several microRNAs with a differential profile between POAG patients and subjects with ocular hypertension (OHT). And some of these miRNAs have these vitamin transporters as target genes (with high target scores), which might explain the lower vitamins amount present in glaucomatous patients.All these results are extremely interesting and provide a lot of information for the identification of new genetic or molecular biomarkers that allow early diagnosis. And also, for the development of new therapies for a better control of this ocular disease, which will help preventing the glaucomatous blindness.