Vitamin C is best known to prevent scurvy and boost immune functions. However, it’s role in maintaining eye health is not something we are all aware of. Our eyes are complex network of connective tissues, fragile blood vessels and nerve cells. Vitamin C is an important co-factor in the synthesis of collagen, a fibrous protein present in all our connective tissues including in the cornea of the eye. It also promotes healthy blood vessels (capillaries) in the retina. In fact, a 2011 study conducted by scientists at Oregon Health & Science University discovered that nerve cells in the retina need to be literally bathed in a very high amount of Vitamin C to efficiently perform their functions .
Generation of free radicals and the resulting oxidative damage to the eye lens is believed to be one of the leading causes of cataracts as well as pathogenesis of other eye diseases, including glaucoma and macular degeneration. Significant scientific evidence exists proving that Vitamin C can protect the tissues of eyes from oxidative changes that happen with advancing age – lowering the risk of degenerative eye disorders and vision loss.
Vitamin C Benefits in Cataracts
A cataract is a common age-related condition that causes cloudiness in the lens of the eye, resulting in reduced or blurred vision. It is the principle cause of blindness across the globe.
The American Optometric Association says that “Numerous studies have linked Vitamin C intake and decreased risk of cataracts. In one study, women taking Vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing nuclear cataracts. Researchers estimate that by delaying the onset of cataracts for 10 years, half of cataract-related surgeries could be averted. Other research showed that women taking a daily supplement with a dosage of 364 mg experienced a 57 percent reduction in their risk of certain types of cataracts.” 
In 2015, a meta-analysis was conducted to summarize the evidence from epidemiological studies of Vitamin C and the risk of age-related cataract. It concluded that higher Vitamin C intake and serum ascorbate might be inversely associated with risk of cataract. 
A 2016 study published in Ophthalmology  also discovered that higher intake of Vitamin C may play a protective role in cataract progression. Participants who consumed more Vitamin C in their diet were linked with a 33% reduction of cataract progression risk and had clearer lenses after 10 years than did participants whose Vitamin C intake was low . The study also revealed that genetic factors contributed to only 35% of the difference in cataract progression whereas environmental factors, such as diet, were responsible for the remaining 65%. However, the study only focused on Vitamin C intake through foods and not through dietary supplements.
The fluid that bathes the lens has high concentrations of Vitamin C, a powerful anti-oxidant that is thought to play an integral role in protecting the inner tissues of the eye against oxidative damage that clouds the lens. This transparent fluid has, in fact, many functions; namely providing nourishment and oxygen to eye tissues, such as the lens and cornea that lack a direct blood supply, removing their waste products and maintaining the internal pressure (intraocular pressure) in the eye to keep it in shape.
Vitamin C Benefits in Macular Degeneration
Macular degeneration is a condition that involves deterioration of the macula, the small central area of the retina that is responsible for our central vision. It is one of the main causes of vision loss in older people.
A 2011 clinical trial, sponsored by the National Eye Institute, was conducted with a goal to understand the risk factors and evaluate the effect of vitamin antioxidants and zinc on age-related macular degeneration (AMD) and cataract. This major, landmark Age-Related Eye Disease Study (AREDS) suggested that when combined with the benefits of beta-carotene, vitamin E and zinc supplementation, 500 mg/day of Vitamin C have the potential to delay the progression of age-related macular degeneration(AMD) and vision loss .
Participants who were at high risk of developing advanced AMD (those with intermediate AMD or those with advanced AMD in one eye) had a 28% lower risk of progression to advanced AMD when they received antioxidant supplements than participants who received a placebo.
Besides advancing age, excessive exposure to sunlight, obesity, smoking, statin drugs, diabetes, previous eye injuries or previous eye surgery, high blood pressure, excessive alcohol intake and genetic factors are also considered some important risk factors for cataracts and age related macular degeneration. People with any of these conditions need to increase their Vitamin C intake.
Vitamin C is indisputably essential to maintain an overall-healthy, well-functioning body. Its role in maintaining the health of our skeletal system, growth and maintenance of connective tissues, scavenging highly damaging free radicals and reducing the risk of cancer, arthritis and cardiovascular disease is well documented. In spite of its critical role, our body is not able to produce Vitamin C on its own. In addition, it is a water-soluble vitamin, which means the amount that our body is incapable of processing and absorbing is excreted in the urine. We can’t store it for later use. This is why we must rely on daily dose of Vitamin C through diet and high quality Vitamin C supplementation to maintain optimum levels and enjoy good eye as well as inclusive health.
- OHSU scientists discover new role for vitamin C in the eye - and the brain. OHSU. 2011
- Vitamin C. American Optometric Association.
- Lin Wei, Ge Liang, Chunmei Cai and Jin Lv. Association of vitamin C with the risk of age-related cataract: a meta-analysis. Acta Ophthalmologica. 2016.
- Ekaterina Yonova-Doing, Zoe A. Forkin, Pirro G. Hysi, Katie M. Williams, Tim D. Spector, Clare E. Gilbert, Christopher J. Hammond. Genetic and Dietary Factors Influencing the Progression of Nuclear Cataract. Ophthalmology. 2016.
- Increased vitamin C in the diet could help protect against cataracts. Science Daily. 2016
- A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E, Beta Carotene, and Zinc for Age-Related Macular Degeneration and Vision Loss. AREDS Report No. 8. Jama Ophthalmology. 2001