Have killed the scorpion king several times,each time I click the altar,Eye of chaos doesn't drop at all!
How can I complete the quest without this item?

I had the same bug and it finally dropped when I looted the Eye before I killed the boss. If that doesn't work for you it could be random chance to get it.

same. never drops for me. gonna try suggestion above.

could not loot the eye when boss was alive, however i clicked the eye right after i killed him and it did drop. maybe I wa lucky or you gotta be close by when you kill him.

This bug sometimes occurs when either:
A) Your game speed is set higher than normal
B) One of your pets/minions gets in the way when it drops

Try:
Setting your game speed to normal and dismissing your pets/minions before looting the eye :)

CHeers, rmuchall. The speed set to normal fixed it =)