It's no secret that our ginormous pony eyes are influenced from Japanese animation. They've pretty much dominated the concept of adorably expressive eyes over the years. I'd even argue that this is one of the big reasons why they are so aesthetically pleasing, and probably a cause for this show's crazy popularity.
An interesting video has popped up over on Youtube going into the history of anime eyes, dating all the way back to some of their first occurrences in art. It's not entirely pony, but it does have a few mentions later on when it reaches Japanese influences on american animation.
Check it out below!