Cast of the Eye
(A). A squint. One meaning of the word cast is to twist or warp. Thus, a fabric is said to “cast” when it warps; and seamen speak of “casting,” or turning the head of a ship on the tack it is to sail. We also speak of a “casting” or turning vote.
“My goode bowe clene cast [twisted] on one side.” —Ascham: Toxophilus.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894