I have a male veiled chameleon and I use the Repashy Calcium plus. I was told by multiple users and the website to use it with every feeding. Repasy puts small enough amounts of the vitamins and such so that you don't have to be worried about when to and when not to dust your food, which is very nice!
Since I started using it, I feel that my chameleon is all around better! His action and health problems went away! Before (when I just used regular calcium and D3) my chameleon was having frequent eye problems and was quite boring honestly. Since I switched, he's been much more active and has had absolutely no eye problems. Also, I have noticed he is much more colorfull! Repashy Calcium plus has vitamin A, which some people think leads to both eye health and pigment coloration.
Because mine was doing so well, my friend also asked to borrow some and his is also much more active and is beginning to be more colorfull. before his would just sit around and was really brown or dark green.