Eyesight: strange visions?

OK so, ever since I can remember me being a child, I think I can remember as far as age 7 or so. Anyway so every now and then when it is fairly bright outside when I look at something for about 4-5 seconds without blinking this odd, tunnel like vision starts appearing. It looks like these dark blobs, kinda tightly packed together start moving toward whatever it is I am looking at in a cone/tunnel kind of way. Now this vision takes about 20% of my visual range so it doesn't really get in the way or anything. It moves faster and faster towards the object in sight, until i cant take it anymore and blink or look away cause my eyes get too dry. It is never bothersome, sometimes I even intentionally stare for as long as I can to see maybe if the tunnel moves fast enough I'll get x-ray vision or something. Guess the question is: has anyone ever experienced this, is it common? Is it a sign of some terrible eye malfunction like glaucoma or something? Or do I have some super vision power and can eventually shoot lasers out my eyes ~_~