Children belonging to the Moken tribe of Thailand have perfect vision underwater. They do is by constricting their pupils and changing their lens shape, just like dolphins and seals. They use this ability to hunt for fish, clam and shells to eat. This skill can be acquired, when exposed to underwater environment enough at an early age – before ~5 years.
Based on da Vinci’s work, there is evidence that the artist had strabismus: one eye is straight, while the other eye can drift. Some forms of strabismus are thought to facilitate artistic work by suppressing the deviating eye, which creates 2D monocular vision advantageous to painting and drawing.
Children from some ethnic groups of southeast Asia (called Sea Gypsies) are capable of seeing clearly underwater and this skill wears off as they grow up. Some suggest that with practice any young person could achieve underwater vision.
A woman from Northern England has 4 functioning color cones (most of us have only 3) and that due to this she can see 99 million more colors than the average person.
Astronauts in the Apollo program reported seeing “streaks” of white light every 3 minutes, even when they closed their eyes.
Some humans can be tetrachromats, which gives them the ability to see more colors than a normal human, like Concetta Antico, an Australian artist who can see 100 times more colors than a regular human.
Humans have the ability to see ultraviolet (UV) light, but it is filtered by the eye’s lens. People who have surgery to remove the lens (typically because of cataracts) can see UV light.
Men and women see colors differently. In general, women are better at discriminating among colors while men excel at tracking fast-moving objects and discerning detail from a distance.
There’s an island in the pacific where many of the residents are completely color blind, only able to perceive black and white colors. However, they often take a psychedelic drug which allow them to perceive colored hallucinations.
There was a woman in 1972 who possessed a visual acuity 20 times better than average. She could identify people at a distance of more than a mile (1.6 km).