you can get lighting hoods for exo terra. they're not made by exo terra, but if you have a scout around, hopefully you'll find some. sorry im so vague on the details.
they fit snugly on top of the mesh, and have fittings for a screw in bulb, and a compact uv bulb. obviously, you'll only want a low watt bulb, dont wanna fry it! they look really nice too, in a chrome finish
i've seen them, just not sure where you can get them from. sorry!