What do his urates look like? (white portion of his poo) If you stick a camera in his face he may suck in his eyes which looks like dehydration. If his urates are white he's probably ok If they are orangish you should work on hydrating him. If in doubt a shower could help.
"Another method of providing water, especially to dehydrated chameleons, is by using a shower. Place a large plant in the tub, aim the shower head against the wall, and run the water so that only a fine mist reaches the chameleon. The water should be room temperature (not hot!). They may drink for up to 30 minutes. Make sure to supervise your chameleon at all times while using this method."