I have a new horse that I worry from my research may have equine recurrent uveitis, but I have never had personal experience with it (I am a vet tech but my tech experience is with cats and dogs). My equine vet is not coming out until next month and I am just looking for an experienced horse persons opinion in the meantime. The previous owner, who didn't know much about horses, thought it was a partial blue eye and said she had never had a problem in the 2 years she had owned her. I did a fluorescein stain which did not show an active ulcer. She has vision in that eye, is not painful, no tearing, squinting or swelling. Nothing out of the ordinary except for the white spot and the blueish ring around her eye. She is a black and white pinto foxtrotter, 10 years old. Sorry the pic is not the greatest, it is hard to get her to let me get a good close up.
I sure looks a lot like some of the Uveitis cases I have seen. Most of the ones I have seen were painful to the horse and the eyeball actually looked like it bulged more the the other eye. My experience with it is that Bute and Antibiotic ointments worked best along with keeping light and dust out of the eye with a mask.
I just think you need a good equine Vet or a Veterinary Ophthalmologist. Any eye problem is serious and needs a specialist. Good luck with it. Let us know what the Vet says.