What Causes A Circle At The Center Of The Eye With Blurry Vision?

I found this explaination of the exact problem that I have on another thread but no answers. I went to a specialist a couple years ago and was told it would go away in time. It did but they reoccur 2-3 times a year for about 6-8 weeks at a time. Anyinfo would help... I have this very strange problem happening only on my right eye, and was wondering if anyone would possibly know what or how it could ve happened. In the center of my vision, in my right eye only, I see a perfect circle. If I stare at a white wall and blink, it appears, as if I have been staring at a bright light for too long. It has a purplish tint to it, and actually makes my vision blurry, ONLY within that circle. My peripheral vision is okay and is not blurry. Also, everything within that circle changes shades as if adding a purple haze to everything. But again, my peripheral vision sees all colors normal. Also, within that circle in my right eye, everything looks slightly distorted and smaller. For example, if i look at a book with my left eye it looks normal and the edges are straight, but with my right eye, the edges look as if they curve very slightly, and the book appears about 10-20% smaller.