Foal With One Eye

[citycat]

A buddy of mine has a mare who foaled this past weekend. He said the foal was a healthy colt but did not have a left eye. There was just a slit there. I didnt know quite what to say. He seemed ok with it and I have know of horses that have run with only one eye but I kinda thought they didnt have an eye due to some kind of injury.

Anyone heard of this? I didnt want to sound crass and ask a stupid question but I know he said he still has to pay the stud fee.