I am 31 now. Almost 15 years ago I figured out that [...]

I am 31 now. Almost 15 years ago I figured out that I had trouble reading with my right eye. The image is not blurry as such but I have trouble with reading text. Letters seem to overlap and its difficult to make out sequence of letters or numbers bunched together. A simple example: lets say there is a number 540000321, I have difficulty figuring out how many zeros there are. I am able to read spaced out letters reasonably well therefore on most eye exams I get 6/6. Also, when compared to my left eye, the image is less 'bright'. Doctors tell me this is how I was born and there is nothing that can be done and no diagnosis is offered.
I have been okay with this explanation as my left eye compensates well enough. However I feel my left eye beginning to experience this as well. Furthermore, the problem aggravates along with eye redness, itchiness and eye fatigue once or twice a year forcing me to visit eye doctors. They treat me for eye allergies but have no explanation for my long term trouble.
My current eye Dr is giving me a massive dose of vitamin A. 25000 IUs every alternate day and had given me zeaxanthin and luetin in the past.

Anybody knows what this is? Doctors seem clueless