Dear Dr. Gamer:

I’ve noticed that if I play Guitar Hero II (or watch it being played) for too long, when I look away from the TV, it seems like I’m still watching the screen. The top half of my vision stays still, but the bottom slowly sinks down. It’s a crazy feeling that I’ve dubbed “Guitar Hero vision.” It’s especially weird when I’m sitting in a chair and staring at a wall — I feel like I’m sinking into the ground. What gives?

— The Bifocal Bassist

Dr. Gamer responds:

Time for a quick lesson in retinal physiology. Vision is the product of an interesting photochemical reaction in the retinal cells of your eye, called rods and cones. Light hits the rods and cones and produces chemical reactions that trigger nerves to your brain, and it’s then interpreted as various colors, shapes, and stuff that you see. We’ve all experienced what happens when you stare at bright lights for too long — you get a glowing silhouette of that light, called an afterimage. The afterimage is the result of the photochemicals being used up by overexposure to the light. It usually goes away after a few seconds because the cells have had time to recover. It’s now time to give this age-old warning: DO NOT STARE AT THE SUN — the afterimage will be permanent.

Our intrepid Bassist has discovered the afterimage effect from staring too long at the game’s scrolling screen image. The effect should subside once your eyes have a chance to recover. If it lasts longer than 15 to 20 seconds, I would recommend a visit to your eye doctor. And while I love Guitar Hero, too, it may be a while before “Guitar Hero vision” makes it into ophthalmology textbooks.

OXM’s Dr. Gamer is actually Dr. Frederick Chen, M.D., M.P.H., from the Department of Family Medicine at the University of Washington. He’s currently testing the feasibility of genetic modifications through BioShock, but his gaming health answers are for informational purposes only and should never replace a true diagnosis or treatment from your family physician. If you have a question for Dr. Gamer, send it to us at letters@officialxboxmagazine.com with the subject line “Ask Dr. Gamer.” But if you have a gaming-related medical issue, go see your own doctor in real life.