Dizzy spells/ vision problems

Has anyone else experienced these? Today was the second time it's happened to me, I was sitting at work and all the sudden I became a little dizzy and my vision slowly started to blurr until it got to the point where I could hardly see. All I saw was a huge blurry circle. After about a half hour of drinking water and sitting back in my chair my vision came back. The nurses checked and my blood pressure was fine, so not sure what the cause was. Anyone have these same symptoms and have suggestions for me?!