According to Homer, the one-eyed, man-eating mythical giant Polyphemus son of Poseidon god of the sea, storms, earthquakes, and horses (for some reason), reigned over his fellow cyclops high in the mountains, himself “a savage man that knew naught of justice or law.” (Homer, Odyssey)

The dreaded cyclops of Homer was deliberately blinded, thus leaving him one-eyed by default, while the cyclops of Euripedes a century later tells of the cyclopes “Poseidon’s one-eyed sons”, presumably not simply blinded but of a race of one-eyed giants living on the island of Sicily near Mount Etna.

Whether it’s Homer, Euripedes, Virgil, or Hesiod, the Greek and later Roman myth of the one-eyed giant has persisted for nearly twenty-seven centuries, 2,700 years! Their origin is still unknown and yet you might find even today his sinister likeness glowering at you from some web-festooned porch alongside Frankenstein’s monster and dancing skeletons.

Monocular Vision Beyond the Myth

As it happens, real people do sometimes have to adapt to living with vision with only one eye. Generally due to injury, though sometimes disease or genetic defect, losing sight in one eye or only ever having sight in one eye, is condition the body and brain are completely capable of adapting to.

Adaptation is a process, it’s not instantaneous. For a person who has lost sight in one eye, the two most predominant differences will be in peripheral vision and depth perception.

Unlike the mythological cyclops with a single eye in the middle of his head, humans and most animals have two eyes working in tandem to provide a complete visual field left to right and distance including depth perception, or the distance between objects creating the three-dimensional visual world we live in.

A person will lose roughly 30% of their peripheral vision on the affected side where they no longer have vision. While the body and brain will adapt to the decreased peripheral field, some impact navigating and observing the world will be unavoidable.

The effects on depth perception may be more temporary as the brain is highly adaptable and will adjust how it interprets visual cues using just the one eye over time.

One Eye? No Problem!

Living with monocular vision is not nearly as scary as the terrifying cyclops might have you believe! When vision in the healthy eye is well cared for, after a period of adjustment people with monocular vision can drive or ride motorcycles, play sports, and live perfectly adapted lives with only minor limitations, and it certainly doesn’t prevent anyone from trick-or-treating!