Pirates have been a favorite subject of adventure stories for a long time. Popular literature and movies have supported the idea that pirates donned eye patches. Like the ubiquitous parrot and wooden leg—early fiction often portrays these buccaneers with a crooked and rough appearance. But is there any particular reason why pirates wore eye patches?
Some pirates wore eye patches to cover their optic injuries, but pirates didn’t typically wear eye patches. A common explanation is that pirates wore eye patches to prepare themselves for seeing in the dark, but no historical evidence supports this claim.
Pirates didn’t have any particular reason to wear eye patches, but trying to answer this question leads to many interesting facts about how they acted and why we think of them the way we do.
Did Eye Patches Give Pirates Night Vision?
There are a few theories as to why pirates would wear eye patches. The first one that may come to mind is that eye injuries were prevalent in pirate life, but there isn’t any historical evidence that would either deny or support this.
Another popular theory states that pirates used eye patches as a way to be prepared for seeing in the dark. But how plausible is this theory? Is there any scientific evidence backing it up?
Pirates didn’t use eye patches to get night vision. Wearing an eye patch may make the covered eye better adjusted to seeing in the dark, but no evidence suggests pirates used this technique.
The logic behind this theory is that pirates needed to be able to see in the dark in certain situations—for example, when they were boarding another ship during the day. Pirates would wear an eyepatch to leave the covered eye already adjusted to seeing in the dark.
During the daytime, the deck of a ship is well-illuminated by the sun. But pirates often had to adjust to the sudden darkness when they went under the deck. As hostile invaders, pirates entering dangerous territory needed to be ready for all eventualities.
A Pirate would then remove the eye patch and let their pre-adjusted eye guide them through the dark cabins.
Otherwise, they would have to wait a while before their eyes became accustomed to the dark. Quickly adapting to the darkness could mean the difference between life and death in the middle of a fight.
One part of this theory is entirely true: the cabins inside a ship were dim. At the time, the only methods to illuminate the interior of a sailing ship were candles and oil lanterns, which were much weaker than sunlight. Besides, not all boat crew would adequately light their cabins.
The center of this theory—using eye patches to see in the dark—is plausible. Going from a brightly lit place into a dark interior leaves people unable to see their surroundings. This phenomenon is called “dark adaptation.” 
Human eyes are sensitive to light. Rods are photoreceptor cells inside the retina that let us see in low-light conditions, and they can detect as little light as a single photon. However, rods become saturated after exposure to bright light, making them ineffective. They need around 20-30 minutes in darkness before they reach their maximum sensitivity.
In theory, wearing an eye patch would give the covered eye time to adjust to seeing in the dark, and it would remain that way as long as the eye patch is worn.
There aren’t many studies on this subject, but MythBusters  found that eye patches helped see in the dark in one of their episodes. This topic is referred to by a medical text from 1943 as “pirate patch,”  and it seems like the US Army explored this technique before 1939. 
However, this doesn’t mean pirates did this—nor was it a good idea.
Did Pirates Wear Eye Patches?
Even if wearing an eye patch is as helpful as it seems for seeing in the dark, it would still be more of an inconvenience than an advantage for a pirate.
Pirates didn’t typically wear eye patches, but some pirates wore eye patches to cover eye injuries. There are no historical records suggesting that pirates wore eye patches.
The historical records on the life of pirates are scant, but those that exist don’t ever mention wearing an eye patch as a way to get night vision or for any other reason.
When considered more carefully, using an eye patch for seeing in the dark becomes impractical.
First of all, fighting with an eye patch is a severe hindrance. Humans rely on their two eyes for having proper depth perception, which would be critical for a pirate in the middle of a battle. The slight bump in night vision would not be worth the decreased visibility.
Secondly, the most important part of boarding a ship was taking control of the deck. After that happened, the pirates won the battle. There probably weren’t that many fights inside the cabins.
But there’s another layer to this myth: pirates didn’t necessarily have to fight on the deck to control a ship. They typically preyed on poorly defended vessels, which the pirates vastly outnumbered by the crew of their chosen target.  The victims usually surrendered quickly, and in those cases, there was no fighting at all.
Why Do People Believe Pirates Wore Eye Patches?
If pirates didn’t have a particular reason for wearing eye patches, how do most people associate pirates with eye patches?
People believe pirates wore eye patches because that’s how famous fiction portrayed pirates since the 19th century. Besides, there have been some notable pirates who wore eye patches.
Some pirates who lost one of their eyes likely wore eye patches to cover their empty sockets. At least one famous pirate wore an eye patch: Rahmah ibn Jabir al-Jalhami, an Arab ruler from the 18th century. 
However, most stereotypical features of pirates, such as eye patches, come from how famous authors and illustrators envisioned them in literature.
Pirates in fiction date back to Robinson Crusoe (1719), but perhaps Treasure Island (1883) by Robert L. Stevenson had the most significant influence on how pirates were supposed to look.  The Golden Age of Piracy during the 16th and 17th centuries inspired these famous authors to create their characters.