The antioxidant qualities of vitamin C help prevent the crystallization and accumulation of foreign molecules that result in the blurred vision of cataracts.
There are also eye doctors that believe that Vitamin C will also help with nearsightedness. Vitamin C is a necessary element in maintaining the structural integrity of the eyeball.
As a matter of fact, the eyes contain the highest concentration of vitamin C than any other part of the body.
For example vitamin E is recycled by vitamin C, so you may need less vitamin E when taken with C.
This is just one example why you would need a balanced vision formula.