In the Dungeons & Dragons mythology, there is an ancient artifact called the "Eye of Vecna". It is actually the mummified eye of the evil god/sorcerer Vecna. In order to use it, the owner has to remove his own eye and replace it with Vecna's. The eye gradually makes you evil and insane, if you weren't already.
The Orcs' main god, Gruumsh, lost his eye to Corellon Larethian, the god of the elves, in a mythic battle. Gruumsh's clerics are often expected to prove their dedication by voluntarily removing an eye, and there is even a prestige class, the Eye of Gruumsh, built around this ritual.
And it has to be the correct eye. If you get the wrong one, you don't qualify for the prestige class. Ooops!
There's a spell called "Eyebite."
Though it is never really explained what an "eyebite" is. All we have is the name and its mechanical effects - which don't seem to include blinding or other sight-related conditions.
Eyebite is a reference to the evil eye.
Worse is the Seething Eyebane spell from the Book of Vile Darkness. It makes the target's eyes explode with acid.
Vecna's agents, vitreous drinkers, aren't quite as gruesome. They "just" stick their long tongue in and steal your sight.
Unknown Armies has a character archetype based around powers gained from stabbing pencils into your eyes. Said Archetype is aptly named "the guy with pencils stuck in his eyes." (It's just a rumour though; no game mechanics are provided.)
Also in Unknown Armies, there's the Summon Unspeakable Servant ritual. One of the ingredients for making the servant is the caster's own eyeball.
GURPS includes Eye Gouging as a Brawling technique which isn't particularly interesting. More interesting (or disturbing) is the perk Long Thumbs which allows you to use Eye Gouging to punch holes in a person's brain.
And then there are the techniques Lethal Eye Poke and Eye Pluck...
In the Nobilis rulebook, there is a short story in which a person briefly sees a small fraction of Lucifer's true form. It's so beautiful that he never wants to see anything but that again, so he claws out his own eyes.
And another where an immortal character is horrifically wounded on the battlefield, including ravens eating her eyes. She lives.
Among the many faces you'll see in the Feng Shui supplement Blowing Up Hong Kong is an eighteen-year-old girl convinced that she is the reincarnation of the goddess Kai Fong Lam, the Harvester of Eyes. She's got a thing for eyes that would make Myca from The Crow proud, and she and her two attendants (cousins on her father's side) drive from town to town one night a week to snatch out the eyes of teenage boys and girls before placing them on a scorching hot brazier back at her temple and recite the glories of Kai Fong Lam's past incarnations as the eyes sizzle into goo. Her unique schtick lets her snatch out people's eyes, Pai Mei style, on a Martial Arts Outcome of 7 or more.
Horror in the Orient Express campaign for Call of Cthulhu features a scripted event in which one of the PCs may have his or her eye torn out by an enemy who needs it for a magic ritual.
In Werewolf: The Apocalypse, Corax wereravens are capable of using the eyepluck maneuver in corvid (raven) form, if sufficiently desperate. They can also use it on corpses to get the last thing the dead guy saw.
Judges Guild's The Dungeoneer magazine #11, article "Monster Matrix". The Acid Spitting Llama can spit acid that does 3-18 Hit Points of damage. They often aim for the target's eyes, with the appropriate result.