My favorite: upon receiving a summons from the Inquisition, "What words can express the consternation of the affrighted Verezzi, as the summons, mysterious and inexplicable to him, pressed upon his straining eyeball?" (80) Just look at that statement literally!
But there's more:
"Julia! Julia!" exclaimed he, starting from the bed, as his flaming eye-balls were unconsciously fixed upon the agitated Matilda." (38)
"He still gazed entranced, but Julia's gondola, indistinct from distance, mocked his straining eyeball." (84)
And from St. Irvyne:
"Unconnected were his expressions, strange and impetuous the fire darting from his restless eyeballs." (111)
"The dark and mysterious gaze of Ginotti arrested his wandering eyeball." (120)
"It was Ginotti, of whose strangely and fearfully gleaming eyeball Wolfstein endeavored to evade the fascination in vain." (137)
"With what anxiety did he watch the dice!-- How were his eyeballs strained with mingled anticipation of wealth and poverty!" (139)
"As if hell had yawned at the feet of the hapless Wolfstein, as if some spectre of the night had blasted his straining eyeball, so did he stand transfixed." (142)
"Why gleams that dark eyeball upon the countenance of Eloise?" (160)
"His form lessened in the clear moonlight; and when it was no longer visible to the straining eyeballs of Wolfstein, he felt, as it were, a spell which had enthralled him, to be dissolved." (167)