I have a 15 yr old appaloosa gelding that I believe has uveitis. I had called my vet approximately 5-6yrs ago when I noticed a sudden white look in my horses eye. The vet came back a second time and brought 3 other associates with him. They charged me a fortune and told me there was no treatment that it was simply a sudden trauma-"he probably ran into a tree". I even addressed the issue of moon blindness, after all he is an appaloosa and they completely dismissed the idea. I've been doing a lot of reading on the internet now, the vets in my area do not have much experience with horses and to be honest after they diagnosed sarcoids as melanoma and wanted to charge me $5000 to have them removed I don't really want to call them back unless it's necessary.
Can anyone please help me to figure out what is best for him??? He is the most loving honest horse and will try his hardest to please you. In the past year I have noticed he has become less sure of his sight and it makes him a little skeptical about things. So far I have been continuing to ride him but I make sure that he is in before the sun starts to go down and I keep him in only the turnouts where he knows the footing.
Is there any affective treatment since he has been "mis" diagnosed for sooo long??? Would it be worth my while to get treatments such as Atropine (1-4%), Cyclosporine, or other steroids??
One thing I'd like to add is that it's a pretty steady condition, some articles described it as reoccurring-it's always there in him.

I also have a horse that has moon blindness, has gone completely blind in the left eye. One thing I want to say is that it will always be thre if that is what it is, and they will have bouts with it. They will squint the eye and it will water some. At this time, some bute or other pain killer is necessary as it is very painful for them at that time. Don't treat this horse any different than another horse ( such as disabled ( They learn to function very well with limited sight in most cases). I am still jumping mine and riding, and plan on showing as long as he is not to antsy about it. Some take it easier than others. Just make sure he is not in a pasture that has aggressive horses in it as they tend to get picked on. Always let him know when you approach the Bad Side. Put a fly mask on in summer, but otherwise try to keep riding this horse. They need to feel like thy have a purpose and you also want him to know his surroundings, and be willing to let you guide him as this will only help later on if he loses his sight all together. Bright light hurts him esp in a flare up of it. Just be aware of how he is acting.

Periodic Opthamalia, Uveitis, Moon Blindness is common in breeds with pink skin around the eye. Apps as you correctly pointed out are more likely to develop this condition. It may be linked to the Lepto virus, and it is unsure why it is more prone to Apps with light colored pigment around the eye. I have also seen a case in a horse that had not been wormed in 7 years. When he was wormed with ivermectin he developed Uveitis.
It is MOST often found in BOTH eyes. I would have an equine eye specialist look at the horse with Uveitis in only one eye. I have seen a guttural pouch infection, gone untreated cause the horse to appear as if he had uveitis in one eye. Within several months the horse became unsteady, then a severe nose bleed. Bled out within 45 minutes. At necropsy, the carotid artery had been attacked and weakened by the fungul infection. The artery wall gave way and he bled out in a short period of time.
I would have the horse with Moon blindness in one eye checked by a vet that is an expert in equine eyes. The horse above had no signs of a chronic guttural pouch problem, no discharge, smell, ect. We assumed the horse had suffered nerve damage in the eye causing the lens to luxate and the pressure to increase in the chambers. We treated the horse with anti-inflammatory medications, pain relief, fitted a race blinder with a cup to shade and shield the eye. All the while she had a time bomb in her head.
Symptoms may be relieved by drugs to relieve pressure, removing from bright light, steroids ecct. The condition will cause complete blindness. If the horse is kept in an area he is well aware of, a small paddock with a buddy. Tree branches kept cut out, any obstructions removed and buckets kept in the same place he may adapt well to complete blindness. However the pressure within the eye may become so painfull that removal of the eyes become necessary. Because a horse is a flight animal, some may not adjust to total blindness.
Horses with sight in one eye can do very well. Pain, pressure treated as needed, the horse often adapts quite well with sight in one eye only. I would research the cause for the loss of sight in just one eye. Uveitis is most often found in both eyes.
Good luck to both horses. I have seen several ponies that were completely blind live to well into their twenties.