I suggest getting rid of the sand completely in both tanks, at least till the mite problem has been dealt with. Both tanks should be completely washed and sterilized, the sand removed from the house completely (mites may hide in the sand, lay eggs in it etc) and crawl back out if the old sand is left lying around for awhile.
Dust from the sand could be irritating the female's eyes, especially if you changed sand recently when this started happening. A new bag may have more dust than normal etc.
I think the basking temp should be a bit higher, more around 95-105 with higher temps available higher up on the basking spot for your dragons to reach if they desire higher temps than normal. Though i haven't kept dragons for long (my first dragon I owned for about 2.5 years before I had to sell her. I only recently picked up a new dragon) I have noticed they go for a much higher basking temp first thing in the morning and after eating. In my old cage I had a large piece of driftwood under the basking light. The temps varied from 120F near the top of the driftwood to around 95-100F along the lower areas of the wood, thus giving a nice range of temps on the basking area for my dragon to move between. The driftwood was large, wide and one end inclined at about a 60 degree angle towards the basking light, providing a large amount of surface area for my dragon to move between, to gain the temps she wanted to be in. The driftwood covered about a third of the tank as well. I wish I still had that piece of wood, it took awhile for me to find it in the first place. But it, as well as the cage, was sold with my dragon. Below is a picture of the tank, driftwood and my old dragon.
I don't see the heat causing problems with her eyes, but if the brightness of the basking light, dust (which tends to be noticeable once the sand is warm and dry) could cause the swelling. Really hard for me to say as I am not a professional bearded dragon vet.
I would find a bigger tank to put your female in, even for the short turn. A 10 gal for an adult dragon is of course very small and also very difficult to ensure a range of temps. Also, an under tank heater is pretty useless for bearded dragons anyway.
For your UVB light, is it a florescent tube light or a Mercury Vapor bulb? Some of the MVB can put out intense amounts of UVB and if too close to the dragon, they can irritate the eyes, though usually this means the dragon keeps their eyes closed, I haven't heard of them causing swelling.
The problem could also simply be due to the mites. If they are bitting your dragon near the eyes, this could be causing the swelling. Then when the mites are full and stop bitting, the eyes may go back to normal size. Unfortunately it is very difficult to 'soak' the mites out of dragon eyes (dragons don't breath underwater after all). Using a spray like Prevent a Mite in the cage (after everything is clean and sterile) will kill all mites, no matter where they are located on the animal. Repeating treatments once a month for a couple months, will also ensure any hatching eggs or migrating mites that get back into the cage, will be killed before they can breed and lay more eggs.
You will also have to cook or soak in a bleach solution, that piece of driftwood. Being wood with lots of cracks, nocks and grannies, it is ideal for mites to lay eggs in, especially if parts of the wood maintain any amount of moisture. If you bake the wood, make sure it is baked at 250F for a few hours, or if you have to soak it, use a stronger concentration of bleach than normally used (one part bleach to 10 parts water). Soak for about 20 minutes and rinse several times, then rinse several times again in cold clean water. Air dry in a very well ventilated area for at least 24 hours to ensure all bleach fumes/residue is gone. I probably would store it somewhere far from where your dragons are kept even then, till all the mites are gone, so the wood doesn't get re-infested.
You probably could keep both dragons in the same cage, on paper towel with rocks/bricks or a sturdy cardboard box (a small rubbermaid container can be used, turned over so the bottom is the top) as a basking site till mites are all gone, in a couple months (to be certain).
You didn't mention if the vet you took her to did any blood work on her. If the vet didn't do it, I suggest calling him and arranging to bring her back in and get some blood work done. An x-ray of your bearded dragon may also be useful, especially if there is any internal pockets of infection (ie absesses or cysts). You can also consider taking her to another reptile vet for a second opinion.
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PHLdyPayne
