Green’s Dictionary of Slang

1. an eye.

1786		‘Peter Pindar’ ‘Ode Upon Ode’ Works (1794) I 411: Giving her two expressive gogglers (Not in the sweet and tender style of oglers) A [...] threat’ning stare?
1821		‘An Amateur’ Real Life in London I 137: [He] grabb’d his pocket-handkerchief, and was after shewing a leg, when a little boy that kept his oglers upon ’em, let me into the secret, and let the cat out of the bag by bawling—Stop thief!

2. a punch in the eye.

1821		‘Battle’ in Fancy I XVII 406: Poor Joh Bull has napt it. What an ogler. How are you off for winking.
1825		Pierce Egan’s Life in London 1 May 109/1: It was a nobber — a facer repeated—a rum one on the ivories—a nozzler, wound up by a tremendous ogler.