Heidi, what I do alot when taking pics of the cats, is get the camera focused, and then raise one of my hands and scratch on the wall or something to get their attention. You can also hold a little foil ball to scrunch and make noise or something. It really opens their eyes up, and even poses the head at a nice angle sometimes.
For this one, she was just laying there with her eyes closed, and when I scratched on the wall she came forward with her head, eyes wide open. Flash was on too, but she had her attention on what I was doing on the wall.
Also, does your camera have a continuous shooting mode? I find that works well also, it takes multiple pics in a row, and if he closes his eyes on the first, you've got a better chance of him opening on the next shots if you are still working on keeping his attention.
This one was shot using continuous shooting. I had scratched on the wall, got her attention, and then she heard Pesty in the other room making noise. That continuous shooting is a wonderful feature!
Those little veins are so neat! Great shots!