No. Severe vitamin a deficiency can cause blindness, but if you live in a developed country you'll be getting a sufficient amount.
Unilkely. There is no evidence that any vitamins will improve your vision. Only one study has ever proven (areds) a beneficial effect of vitamins for any eye disease, that is, a certain formula of vitamins has shown a slight benefit for patients with certain stages of macular degeneration. I am unaware of any other studies.
Maybe and no. Unless your poor sight is due to advanced age related macular degeneration, there is no good evidence that vitamins will help your vision. I am assuming, of course, that you do not suffer from a vitamin deficiency. Your eye specialist is a great resource to discuss other measures that will help you specifically.
YES. Our body needs numerous nutrients to function properly and unfortunately the highly processed frozen diet that we eat does not have adequate nutrients. Eye is very active organ in our body & will benefit from good quality supplements.
Depends. There are many reasons for poor eyesight, and ways to improve it range from simple glasses to laser to surgery. Supplements like omega-3 have been shown to help with dry eye/blepharitis, and macular degeneration, and vitamins a, c, e, copper, zinc, lutein, zeaxanthin, etc. Have been shown to help slow down certain types of macular degeneration. See an eye md (ophthalmologist) for more advice.
See opthomologist. See a doctor who specialized in diseases and surgery for eyes. Research your options with the specialist. There are no supplements known to help.