"Blurry" can be many things. You say it clears up after a couple of hours ...? Could it be migraine aura without the pain? Most of my migraines are aura-only and blurriness is the first impression those give (perhaps the only one, unless you get fascinated by their details in which case they can be quite "pretty" in a wierd and scary sort of way - like rainbowing crystal saw blades spinning in opposite directions), so the thought struck me. I have that occasionally. Bears looking into. If that's it, then a simple OTC pain-killer at onset can be helpful sometimes, and checking out possible "triggers" can help you avoid this becoming a more frequent issue. So ... If your ophthalmologist doesn't find an answer, you might want to check with your gp. Best of luck!