hypovitaminosis A unlikely imo
like the previous poster pointed out, the help form is almost a necessity for an issue like that. it would be good to pay extra attn to the lighting and supplementation sections. probably better not to give anything, until you have at least an idea of what the problem is. a vet visit is probably in order, because an issue like that can go downhill in a real hurry, if you are unable, then it probably wouldnt hurt to raise his light, and lower your vitamins, until the problem is better understood. if its affecting both eyes the it is not likely a debris issue, more likely it would be a lighting or supplemental issue. do you use a cfl, if so what kind and how old is it. if he gets any multivites at all, i would say that vitamin A hypovitaminosis (vitamin A deficiency) is extremely unlikely, most xanths do quite well with very little multivite supplementation, and hypervitaminosis A(excessive vitamin A) is far more likely, especially if your multivite uses higher dosage preformed vitamin A (like reptivite)a safer choice would be herptivite (uses proformed vitamin A beta carotene instead) better still a lower dosage multivite product like repashy supermin. another possible culprit could be the dumping of heavly dusted feeders from above. also spraying with a vitamin can cause problems. i suppose it could be a bacterial or fungal infection as well. are his eyes clear or cloudy? & does he ever leave them closed during the day? jmo