Traumatic optic neuropathy (TON) refers to an acute injury of the optic nerve secondary to trauma. The optic nerve axons may be damaged either directly or indirectly and the visual loss may be partial or complete.
In Minecraft, emerald ore is very hard to find and is found in small deposits in the Extreme Hills biome. You can usually find emerald ore between 13 and 31 blocks below the ground and close to lava. So if you see a pool of lava in the Extreme Hills biome, that is a great place to start mining downward.
Emerald is an extremely rare gem in Minecraft (even rarer than the Diamond). It is the main currency used in the Villager trading system. Emeralds can be mined from Emerald Ore, which can only be found in Extreme Hills Biomes and Roofed Forest Biomes, making them extremely rare to find. Emeralds will only drop when mined with a Pickaxe made of Iron or Diamond.