I hadn't thouhgt of a spotlight, but it can be done by using a web background square (particularly the ones that look like fire). Now here's the trick, you use the web back as the texture for all parts of the eye and use the same colored web back (Not a black and white one) for the reflection map and make the ball about 50% transparent. It does give a glow that satisfactory and then can be enhanced in a paint program after rendering. I know, I tried this because I wanted my vampire's eyes to glow red.