A very unscientific observation-
I think many here on the forums worry too much about limiting vit a and vit d3.
Throughout the 90s when I was *really* into chameleons (kept and bred numerous species) I used d3 most feedings that were indoors (which was about 7 or 8 months out of the year from the mid 90s on, 12 months out of the year in the early 90s and the product used was rep-cal with d3) and vit A 1x every week or two (via reptivite which also had d3). Summers in the latter part of the 90s I mostly used plain calcium only because the lizards were outdoors at that time and I only occasionally (couple times a summer) used multivitamins.
To the best of my knowledge I never had either a d3 or a vit a overdose.
I did have several clutches of panther eggs not hatch out after I switched over to herptivite only in the late 90s and always wondered if lack of vit a in that product was the reason. I don't wonder anymore- many on here are using that product exclusively without hatch failure. So I don't know what happened there at the end.
I have to add that I was usually using inferior UV tubes or tubes that produced no UV lighting at all during most of the 90s. The first part out of what was available (vita-lites and blb blacklights) somewhere in the middle out of what I thought produced UVB but didn't (chroma 50s) so I don't know what effect say a reptisun 5.0 would have in combination with the d3, but supposedly it is impossible for a lizard to overdose d3 from UV exposure, therefore I would think that if receiving sufficient in the diet, the body simply wouldn't do the conversion from the UV light, so I wouldn't think my experience would have been much different even if I had the good tubes during those years, or even if using it out-of-doors.
I'm not saying do what I did (better ideas exist nowadays-probably those days as well), but I do think some of the fears expressed on here about overdose are a little extreme in the opposite direction. A little vit a via a multivitamin supplement dusting on prey items once or twice a month for species like veileds and panthers is unlikely to cause problems in my admittedly very unscientific and simple layman's opinion and is likely to prevent more problems than it causes. Same goes for d3- 1x a week is probably going to prevent more problems than it causes.
I see an awful lot of eye problems, clumsyness, falling from perch, grabbing limbs with other limbs, bent casques, etc here on the forums that I've never experienced and I always wonder if is because of the current trend of very minimal supplementation alongside minimal basking temperatures.
To the OP-
I purchased some jewelled lacertas a couple of years ago that arrived with vit-a deficiency and their symptoms looked exactly like eye infections- very similar to the photo that started this thread.
I think it could be a vit a problem, but as others are cautioning, it could also be an infection of some sort. Any vet should have access to antibiotic eye ointment (for cats for example) and baytril (for dogs for example), and you can find the dose for the latter online, and the former you just apply a small dab directly to the eye. Probably one of those would be a solution, but I'd encourage you to talk it over logically with a vet even if reptiles are exotic to them and volunteer product names and dosages you find online for lizards. The vet should be able to logically work through until you have your solution- animals are animals and the difference would just be knowing the product names and dosages- and in this kind of thing the products are not usually reptile-specific. If the lizard is otherwise strong and healthy, you could try a little vit A and give the lizard a week or so to see how it responds, and if it doesn't then approach the vet with a brand name of antibiotic eye ointment and dosage for baytril and see what the vet thinks.