Despite some mistaken characterizations over the years, Popeye is generally depicted as having only one blue eye, his left. In at least one Fleischer cartoon, Bluto refers to Popeye as a “one-eyed runt.” It has never been revealed specifically how Popeye lost his right eye, although he claims it was in “the mos’ arful battle” of his life. Later versions of the character had both eyes, with one of them merely being squinty, or “squinky” as he put it.
His brain has extensive physical damage, to the point that it can not process input from both eyes at once to create a 3d image without resulting in a lethal stroke.
If he opened his eyes, he would die.
Popeye is actually a characterization of the Norse God, Odin. Also know as Odin-One-Eye. Odin sacrificed his own eye to gain knowledge.
It is also obvious that Bluto represents Loki, Olive-oyle, the goddess Lofn and, of course Wimpie is Baldr.,
All Popeye cartoons can be viewed as simplified graphic depictions of Norse (Aryan) Mythology put forth in an overly uncomplicated manner to introduce the illiterate US masses to the concept of a Master race. Aryan master race ideology was common throughout the educated and literate strata of the Western world until after World War II. Such theories were commonplace in early-20th century but understanding was well beyond the intellect of the basic United States television audience so it was decided to present them in a form more to their intellectual level; thus the cartoon format.