Abacination is a form of corporal punishment or torture, in which the victim is blinded by infliction of intentional damage to the eyes.
[1] In one account, a corrosive chemical, typically slaked lime, was contained in a pair of cups with decaying bottoms, e.g., of paper.
The slowly draining corrosive agent from the cups eventually ate away at the eyeballs.
[2] Blinding as punishment has existed since antiquity, and is documented as a form of torture in ancient Persia, Greece, and the Byzantine Empire.
[3] Known accounts of abacination include John IV Laskaris (inflicted by Michael VIII Palaiologos),[4] Alexios Mosele (by Constantine VI), and Constantine VI (by his mother, Irene of Athens).