"Well, this is a unique sight," he said to her, as the oldest man alive entered the zone. "It's Old Blue-Sclera! To what do we owe the presence?" he asked of the old man. For all of the youth-preserving and longevity technology, somewhere in the mix, human sclera ended up changing from white, to yellow, to green with age, though they almost always remained white for the first 200 years. In this way, they were a rough gauge of age when all else failed, though age could usually be found via a meeting of the minds, anyway.
"You know," the old man - who looked to be the same age as anyone else - said, "what strikes most people as odd is my existence, but what strikes me as odd is my uniqueness. Tell me, do you think that yours will ever become green?"
"Oh, I doubt that," replied the woman in her partner's place, "I can feel him getting bored with life as the weeks go by. He probably won't last another thirty years."
"As always, I wish that I could help," replied the old man, "but I never did know why I was different." With that, he took his leave to go across the way, meeting with a woman who was only 185 years old.