Long Island-native Christian Guardino struck a major chord with the judges on ABC’s “American Idol,” earning him a spot among the show’s top 24 contestants — and a trip to Hawaii to compete at Disney’s Aulani resort. Guardino, 22, was born with a rare condition that causes blindness, but he beat the odds and is now on the road making a name for himself on one of the industry’s biggest stages — which he told The Post’s Angela Barbuti is “so exciting — but it’s craziness.” Can you explain the condition you had as a kid? I was born with a rare disorder called Leber congenital amaurosis, but we call it LCA. It’s a disorder that causes a gene that’s missing in your eye, because if the gene isn’t there, it’s not producing proteins that your cells need to live, so they all start to die off and then it causes inevitable blindness.