I will say one more thing about sunken eyes....the chameleon may be dehydrated but trying to correct the dehydration won't do much when the chameleon has other issues that are causing it to be dehydrated....like a mouth that's too sore for it to eat and drink, kidney failure, heart issues, infection, and a multitude of other things that are the real cause for the chameleon's state.
It's like saying...the chameleon's stomach had no food in it so it died of starvation when the truth of the matter was that the chameleon had a reason for not being willing/able to eat...like cancer, kidney failure, etc, etc.
So maybe technically it's dehydrated...but that's not the real reason for the chameleon going down hill. Hope this helps to explain it.