Hey,
It's always hard to figure out the problem when husbandry is good, the owner is knowlegable, and the cham has gone through basic vetcare. Here are some suggestions that may lead to nowhere.
(Note beforehand: My blue bar ambanja did not fire up for the first time until 9.5 months. It was worth the wait...)
1)Water- I would always check water source that is misting. If it is tap water, chlorine could be a factor in chronic irritation. If it sits for 24 hours it will often evaporate off. A good way to check if it is something from a well water source is to try spring water for a week.
2)Neopolydex does have a steroid component to it. This is good for chronic irritation, but may not so good if there is a cut on the cornea. Tobromycin without steroids might be worth a try. Also, if you don't see a pretty quick response to topical steroids initially, it probably is not the answer.
3) Some chams are spazes in their enclosure and are constantly poking part of their head moving through brush. I like ficus, but this might be a poor choice for your cham. You might try a week with only the schefferlaria and various vines.
4) I would put more and varying vines at the top of the enclosure so that he can have more of a gradient being close to his UVB. Though MV bulbs are more of a problem with burn out and higher levels at the initial use of the bulb, I imagine some fluoro lighting might have a similar, but lesser impact. If you changed the lighting within 1 month of the problem, I might get a new fluoro light. If not I might limit UVB to two sessions of 45 minutes a day. This will allow needed UVB, but turn it off to make sure he is not overdoing it.
5) Vitamin A could be an issue. For this vitamin I'm more of a naturalist (I do not wish to get into any debate as to supplementation). I think that feeding carrots or other veggies high in vit a to your feeders might be helpful (I'm one of those that believe that though many chams cannot convert beta carotene, many insects can.
Anyway, that's my 2 cents.....quite possibly I made up all that stuff
Matthew