Orthotes

Orthotes (Greek:ὀρθότης "rightness") is a Greek philosophy concept which means approximately "an eye's correctness". In Plato's philosophy it is said to be the passage from the physical eyes to the eyes of the intellect.

At least this seems to be the interpretation of Martin Heidegger (as says Marilena Chaui in her philosophy classes at University of São Paulo) in his "Plato's Doctrine of Truth".