We have a 7 yr old OTStdbd. She's been with us for almost three years now.
She seemed very high strung when she arrived. I attributed this to being basically right off the track. She was difficult to lead and unpredictable when tied, unless in cross-ties. She was disrespectful of my space and of me in general. After some months of ground work, her manners greatly improved to the point where I would allow my un-horsey 12 yr old son to lead her. Then I finally rode her. She was definitely on a learning curve with the riding, but putting that part aside, she was extremely hesitant to go to areas she was unfamiliar with and where other objects were within 5 feet, although she is fine in the bush. She is much more confident in the same areas if I am on the ground rather than in the saddle.
I have always figured that after a couple of years of being with the same people, in the same home, with the same care she would mellow.
However, I am now wondering if something else is going on. She does have a very sweet personality. She loves attention. She is playful and bossy in the paddock. She is healthy as far as I know. No issues with weight, worms, feeding, feet...
Somewhere along the line I started to wonder if her vision could be causing her some trouble. She doesn't stumble. She doesn't carry her head unevenly or unusually high or low. She doesn't move her head from side to side (as a horse with less vision on one side might). She does toss her head undersaddle, on the lead a bit and in the paddock a bit. It seems to me that her head-tossing is directly related to her level of frustration; I have never linked it to vision.
She is not blind. That I know. She doesn't seem to have a limited field of vision. But perhaps she has poor vision? So instead of 20/20 it's 15/20? How could I tell? Can a vet actually measure visual acuity? Is there anything I can do at home to try to determine how well she can see?