I have 2 fell ponies with cateracts. They have the same dad but different mums. Flynn was diagnosed at 18 months old with juvenile cateracts. The vets said they would either stay as they where, go worse and he would go blind or in very rare cases go smaller. Heis special and they have gone to tiny pinpricks. We fully expected not to have him at 8 yrs old, as he was struggling with depth and light and dark. He is so much better, still reactive, but we are considering backing him this year, he is 9 this year.
His half sister Lorel, developed them 5 years ago, she is 11 this year. There are 5 in one eye and 9 small ones in the other eye. I have retired her, in part to her spooking and my lack of confidence, plus she also has a back end issue and intermittent lameness. Both ponies are very happy.