I have two here. One developed horrific cataracts at an early age - he was 8 when diagnosed. At that point, I did contact a specialist and was told there is really nothing we can do except… Remove the lens cap - which means the horse’s eye must be protected at all times, risk of infection very high, blah, blah, blah. I rode him for about a year after that, but he just got spookier and spookier. I tried riding him with “blinkers”, but finally gave up and retired him. He has partial vision, and is out in the back pasture with a companion rescue horse that has foundered multiple times. They are best friends and have a happy life.
Second horse is not mine, she just boards here. Uveitis and is about 98% blind - has very limited vision in one eye. Owner did continue to ride her for a while - she is a very trusting mare, and very smart. But eventually retired her. She functions fine - anytime I need to mover her, I walk the pasture fence with her, walk her to the water, and she does fine. I try not to move her too often. I got her a goat companion about two years ago - they are BEST friends. Every once in a while, she runs into something - she gets more then her share of scrapes on her head, but all in all, she functions quite well.
I don’t know if either of these stories helps you or not - neither horse is a riding horse anymore, but they both live happy lives.