I have got 2 mare that are full sisters, registrated quarter horses, they both went blind in the right eye at different ages.  Has anyone experienced something like this in their full sibling horses?  Kind of worried because we have a coming 3 yr old out of the one mare and the 3 yr old gets a watery right eye at times.  

Maybe a good repro vet might know. But, out of curiosity, what caused the mare's eyes to fail? Why is the colt's eye watery? 

What was the cause of blindness?  If it was equine recurrent uveitis, one of the most implicated causes is lepto infection.. and lepto is picked up in the environment. so while not heriditary, they could both be equally likely to be exposed to the same deal. 

Now if they were both born with juvenile cataracts I would say that explains it. 

Have you ever had a vet investigate when the eye is watery? If they are having uveitis flares and you catch it early, you can prolong their sight. If you don't, you may not notice it until they have a huge cataract and a trashed iris. 

the first mare was a fast flare up. Her eye clouded up over night, had no problems before that.  Second mare I thought was Seasonal allergies in fall, her eye would water a little bit very fall for about 2 weeks.  The young started this winter.  No I haven't had a vet out yet.  No that I half day off I can get an appointment to have the vet out