Wikia

The Left Eye of the Falmer is a larceny target in The Elder Scrolls V: Skyrim and can be found in Irkngthand.

AcquisitionEdit

It can be looted from Mercer Frey's body along with the Right Eye of the Falmer during the quest Blindsighted and its only use it to be sold to Delvin Mallory for gold.

After it's been sold to Delvin, it will be on a bookshelf near the Thieves Guild vault in The Ragged Flagon - Cistern.

PC 360 PS3 Often times when this item is looted from Mercer Frey's body, the quest to deliver it to Delvin may not activate, and he won't take it. When this occurs, the eye is not marked as a quest item, making it droppable, storable, or sellable, becoming just like the right eye.
PC Using the console enter : SetStage TGlarceny 80 to give yourself the quest to return the Left Eye to Delvin, then add the Eye to your inventory with the console ( player.additem 1994f 1). Then return to Delvin Mallory to turn in the quest. DO NOT LOOT THE LEFT EYE on Mercer before turning the quest in, the quest simply disappear (it completes the quest itself) from the journal as soon as you loot the Left eye off the body. (Bug reason: the code written for the left eye of the Falmer apparently is "completes quest" instead of "starting quest")
360 You can escape Irkngthand without taking the Eye, take the rest of your items back to Delvin, sell them, and go back to get the Eye off of Mercer's body.