Thanks for the clarification!
Is this what the OP is asking about? I think this eye gives a horse a very intelligent look. In my experience there is no difference in personality (or anything else) in horses with more, or less sclera. It would be the last thing I would worry about when selecting a stallion. Unless you are dealing with Appaloosas, it will not be passed on reliably. Some foals will have it, some will not.
I had a TB mare, minimal white (ie one front sock and a star, strip and snip) with one eye with more sclera. (I called it walleye too!) Her star was over on the left side of her forhead, same side as the eye. She had one foal with me, a full TB filly, with no white except one back sock, one WB (Dutch) foal the following year on a free lease. WBX filly had tonnes of white, huge blaze, 3 stockings. I sold her the following year and she was bred to a big Tobiano Paint, resulting in a blk/white tobi colt. All 3 had normal eyes!
So as far as inheritability, I’m sure it is there but IME even with breeding her to colored type horses she didn’t pass that trait on easily.
She is now owned by the new owner of the Tobiano Paint and will have many paint X babies, so I’m interested to see what happens with her down the road.
[QUOTE=JB;5628498]
Maybe rcloisonne is making the connection between the prominence of the white sclera and uveitis together in appy characteristics?[/QUOTE]
I’m sure you are right JB. That would not be a correct correlation however. (But I’m sure you already knew that!)
I know that veterinary studies have shown that uveitis is most common among Appaloosa horses that exhibit a certain type of spotted coat pattern - i.e. the more white on the coat of the horse (all-over roaning in particular) and the less pigment around the eye (the actual SKIN around the eye, not the sclera) the more likely it is that the horse will develop uvietis.
For example, a horse with this color pattern:
http://media-2.web.britannica.com/eb-media/57/5757-004-CC3AF449.jpg
Is much more prone to uvietis than a horse with this pattern:
