Below is a walkthrough for the Eye Lost It side quest in Tiny Tina’s Wonderlands. To obtain this quest, speak with Dardanos in Overworld.
Search for the eye
Head south to the objective to trigger more dialog. Afterwards, follow the objective to a dungeon. Head inside and complete the encounter.
Reach cyclops lair
Head to the dungeon near where you accepted the quest. Complete the encounter then loot the eye from the chest that spawns at the end.
Talk to Dardanos
Speak with him to complete the quest.