I was a PhD student in the School of Optometry (though my PhD was nothing to do with eyes). Every week we had a guest speaker come and give a talk to the department, either a scientist working on eyes or clinicians developing new techniques. Some of the talks, to this day, make me squeamish.
One was from a clinician treating burns victims - specifically when the eyes had been burned. He was developing a form of contact lens that would protect the burned eyeball and stop it adhering to the eyelid (also burned) whilst the healing process started. The pictures he showed...even now I feel a bit ill, 20 years on.
Another speaker put me off laser eye surgery for life. I don't need glasses, thankfully, but if I ever do Ill never get laser eye surgery. Having watched a video of it being done...ooft.