Apparently blue eyes are a requirement in our equine family. Not really intentionally, but out of 4 horses, one pony, and one mini, all have one or both blue eyes, except the pony. The mini and two horses have both, and the other two horses have one of each.
A blue eye also called "Glass" eye, "Moon" eye, "China" eye, "Wall" eye or "Night" eye is when a horse has a blue eye instead of the most common brown eye. The blue has no pigment and is more prone to cataracts. Some people also say that the horses is blind in that eye which in most cases is not true.
I think it looks pretty cool. Our paint filly has it and she has it in the shape of a "C". It kinda fits since her name is Corona :P