Take a picture of someone you think has good eyes or good eye sight.
Spend a minute or two each day looking at that picture and visualizing yourself having good eyes. Follow it up with any affirmatins that you want to use:
"My eye sight is improving daily"
"I allow my eye sight to improve"
"I allow my eyes to be healed"
And so on. Whenever any doubts come up, replace them with your affirmations.
What is happening is that you are sending these new ideas to your subconscious which will go about manifesting them in your body.