Your vet told you to treat it yourself, didn't tell you how and to come back if it isn't better?
That's a bit odd.
I don't know why he wouldn't just give your cham a vitamin A injection and he should have examined inside your cham's mouth to check for signs of infection.
Does he normally treat reptiles or is he simply willing to treat them?
The question is, why did your cham develop a vitamin A deficiency?
Rolling the eye around beneath the lid is a sign of eye irritation but doesn't indicate the cause.
The white around his mouth might be normal if he is growing and his colors are changing.
The picture is rather blurry.
Basically eye issues are fairly common cham troubles and can be caused by any of several things--some of which can cause/be caused by others:
1) Infection, which can be due to injury, environmental issues, nutritional deficiencies or parasite problems
2) Malnutrition which can be caused by failing to gutload feeders or failure to feed a varied diet, improper supplementation, parasites or simply a higher need for a particular nutrient in an individual chameleon
3) Irritation--sometimes a cham's eye is irritated by something in their environment, such as too little humidity, sap from a plant or a bit of something getting into the eye (shed skin, soil particle, etc.)
The first 2 problems are best treated by a vet, since too much of a vitamin can do some pretty bad things.
It is important is to carefully review your care, whenever a health issue arises, as even infections are often caused by environmental issues.
For the third problem, gentle, repeated flushing of a cham's eye with a sterile saline solution designed for use in eyes will typically clear things up, but if there isn't substantial improvement within a day or two, it's time to see a vet.
FWIW, I've used this one
http://m.cvs.com/mt/www.cvs.com/sho...Sensitive-Eyes?skuId=458126&un_jtt_v_menu=exp
Bausch and Lomb makes a solution with the same ingredients as Sensitive Eyes Plus.
Ataraxia has written a detailed post that includes how to carefully dose with vitamin A.
https://www.chameleonforums.com/eye-problems-76636/
