Same thing when I had my Aimpoint PRO. What I found is if you shoot with one eye open anyways, just pop up your rear buis (if installed) it will sharpen right up. Defeats the purpose of having a red dot but that's one option.
I see a cluster of dots due to my astigmatism. Had a chance to try out a buddies ACOG, man that thing is clear, and the dot was sharp. I heard ACOG are better for people with astigmatism (maybe FUD tho)