"There are moments in your life when everything crystallizes and the whole world reshapes itself right down to its component molecules. And everything changes. I have looked upon the face of a Vorlon...Laurel. And nothing is the same anymore."
He performed surgery on Vorlon ambassador Kosh Naranek when he was critically injured in an assassination attempt, making him the only known human at that time to lay eyes on a Vorlon. Bound by his oath of confidentiality, he never told anyone what he saw.  
He left Babylon 5 in late 2257. Shortly before starting his new job as head of Xenobiological Research at Earth Dome, he ran into Doctor Stephen Franklin who on his way to Babylon 5. . Dr. Kyle finally retired in December 2262, he asked Doctor Stephen Franklin to again fill his position.
- Although he is mentioned several times throughout the series, he only appeared on screen once in the The Gathering.