1) Fake peeper 2) Faux peeper 3) Optical illusion 4) Peter Falk feature 
• (n.) A fish of the great lakes; the wall-eyed pike. • (n.) A species of blindness in horses in which the eye is bright and the pupil dilated; a sort of amaurosis.
Glass'eye` noun 1. (Zoology) A fish of the great lakes; the wall-eyed pike. 2. (Far.) A species of blindness in horses in which the eye is bright and the pupil dilated; a sort of amaurosis. Youatt.