Between the 18 century, the Caribbean was a place without laws and government. There were numerous merchant ships crossing over and over with no authorities to protect them. With these factors, privacy reached its golden age. Pirate life has always been something inspirational for blockbusters. But many on the silver screen are not historically true. They did not walk the plank, they rarely buried treasure, and they were not always criminals. One thing that was true about the pirates was that some of them wore eyepatches. But why pirates wore eyepatches?
Common knowledge about why pirates wore eyepatches?
Among some possible reasons, a widely accepted theory is that pirates wore eyepatches because they had lost one eye. Life of pirates was full of battles and attacks. Losing an eye was something normal.
Another reason was that pirates used eyepatch was to protect their dark-adapted vision. This would have been in case they needed to go under deck.
Illumination on night vision and day vision
Human eye can adapt rapidly from low light or night conditions to daylight. However, it will take as much as 25 minutes for human eye to adjust from daylight to low light levels. The reason for this is that there are two types of light receptive cells in eyes, cones, and rods. All of them are responsible for color vision. While cones are the predominant light-sensitive cells for daylight vision, rods are for the night vision.
While the lighting conditions change, cones quickly adapt while rod will take a longer time to adjust. Cones are somewhat responsible for adapting to low light level conditions, but they are not really effective in dim light. Accordingly, human eyes need time to help the night vision fully activate.
Advantages of the pirate eyepatch
When on ship, pirates would take the deck, and then they might have to go beneath the ship to finish the combats against enemies. Or if unlucky, their ships were overtaken, they would be taken below the deck by enemies. While going under deck, battles would be more difficult since it would take a while for their eyes to adjust to the darkness so that they could see their attackers.
One possibility is that pirates, while on deck, would wear the eyepatch over a dark-adapted eye and use their daylight-adapted eye to fight. When they went below deck, they would use their dark-adapted eye. This would have given the pirates a fearsome advantage over their opponents since they would be able to see more clearly than their adversaries and be able to surprise them.