LOUISVILLE, Ky. — His name is Patch, a horse with one eye, and he’ll be running in the Kentucky Derby. How he lost the eye is a mystery.

“No one really knows,” trainer Todd Pletcher said.

Pletcher has two other horses going in the first leg of the Triple Crown at Churchill Downs – Always Dreaming and Tapwrit. But if Patch comes up big, he’ll be the first Derby winner with one eye.

As it turns out, Patch is not the first visually impaired colt to run for Pletcher at the Derby. In 2004, Pollard’s Vision finished 17th. Pollard’s Vision had sight in only one eye when Pletcher purchased him as a 2-year-old. It didn’t prevent him from becoming a multiple stakes winner of more than $1.4 million.

Patch has adjusted to a limited field of vision. But the circumstances surrounding his condition are murky.

“We came in one morning and his eye was a little bit swollen, and he was tearing heavily,” Pletcher said.

There was no evidence of additional trauma, suggesting the colt had fallen or run into an object. Aggressive treatment failed and the eye was removed.

“Everyone is stumped as to exactly what happened,” Pletcher said.

Once Patch recovered, Pletcher wondered how he would respond. The horse had already started training. It was never an issue.

“We thought there might be a period where he needed to adjust, that he would carry himself a little differently,” Pletcher said. “Actually, he showed no ill effects from it at all.”

Patch has one win in three starts.

Patch figures to be a long shot Saturday, but already he has a following on social media.

“I kind of anticipated Patch would become pretty popular,” Pletcher said. “It’s an intriguing story.”