I agree that the the eye condition was most likely caused by physical damage. You could leave it in the DT and see if it heals by itself. But like any physical damage, there is dangerous of secondary infection. Also the fish must be in pain now (if you belive fish can feel pain).

My fish have scratched their eyes on the rocks before, kinda looks like pop eye but it's always just one eye that's effected so I know it was a physical injury. Very first time I saw it I caught the fish put it in QT treated it with med.'s and it died :sad: Since then (it's happened to 3 of my other fish over the years, right now my powder blue tang has an eye scratch, but it's been a week and it's almost healed now) I leave the fish in the display and do nothing, it always heals on it's own in the display (without med.'s) within two weeks.

Pop eye can be either one eye or both.

when it's one eye it's usually a shock or an infection. when it's both it is usually a kidney problem and usually fatal.

Pop eye is a condition where the eye is poping out of the head and yes it can happen with only one eye. I treated my niger trigger pop eye with Paraguard in a quarantine tank and he's 100% back to normal today. It took about 3 weeks to treat and maybe 4 to 6 weeks to completely return to normal.