I've been playing MAME on my 27" Trinitron TV today, for about 30 minutes, and my eyes where literally crying in tears (no, not just joy , LOL!) because of how close I was.
Most likely you are not blinking often enough and your eyes are drying out. Look in the mirror and see if you have a nasty horizontal band of bloodshot across your eyes. When I first got into computers, especially FPS games, I would get so wrapped up in the game and concentrating on the screen that I would literally forget to blink. I kept a bottle of eye drops nearby for a couple weeks untill I became used to the computer and now I dont have a problem or a need for the drops.
Also, check the brightness of your TV. When you are that close to the screen you may want to back off on the brightness a bit. Especially if the room is dark. (like an arcade)
Another problem of extended play is that your eyes will focus intensly on the screen and when you are done everything will be blurry till yours eyes realize that there is life beyond 15 inches away.
All you really need to do is take a break now and then.
Thats what the pause button is for.
