Black Lens

Black Lenses are an item added in the 1.0.3 patch. They are dropped by Demon Eyes and have a 1 in 150 chance of being dropped. They are used to craft Sunglasses and cannot be used to make the Suspicious Looking Eye. Blood Moons are useful for collecting these, as Demon Eyes spawn more frequently. A common strategy is to make a tunnel underneath one block of any material and then cover those blocks in enough lava to kill the Demon Eyes, but not enough to burn the drops.