Ever wondered why pirates wore eyepatches? 

When you visualise a pirate, what comes to mind? You probably see a skull and crossbones flag, a three-cornered hat, and almost invariably, eye patches. For at least a century, pirates have been depicted in literature and history wearing the ubiquitous pirate eye patch. In fact, if you are asked to dress up like a pirate, you’ll most likely include an eye patch as part of your costume. 

Did all pirates wear eyepatches? 
The pirate image that we have built in our minds comes mostly from their fictional presentation. Notorious for being combative, pirate characters in fiction have been shown with an eyepatch covering their injured or missing eye. Remember Long John Silver, the lead pirate character of the novel Treasure Island? He had an eye patch. Patchy the Pirate from SpongeBob Squarepants, an American animated comedy television series, also had one since he was born with only one eye. Also, who can forget the iconic One-Eyed-Willie, the pirate captain of the ship Inferno from The Goonies (1985 American adventure comedy film)? He was known for his eyepatch which he started wearing at an early age. However, Captain Jack Sparrow, the main protagonist and the legendary pirate of the Seven Seas in the famous movie Pirates of the Caribbean, was without one. 

So did pirates wear an eye patch in real life? Well, Rahmah ibn Jabir al-Jalhami, one of the most successful pirates of the Arabian Gulf, famously wore an eyepatch, after he lost an eye in a battle. But, may be, not all of them did.  

A way to hide the missing eye or sharpen vision?  
There is an interesting perspective about why they wore them. It wasn’t necessarily to hide their missing or injured eye but to condition the eye so that they could fight in the dark.  

A pirate’s life at sea is hard. Imagine juggling between upper and lower decks of the ship navigating every inch of their vessels in bright sunlight and in dark to survive. You may know this that the lower decks of a ship at sea are dark while the upper decks are very bright — especially because of the light reflecting off the water. The challenge here is that it takes 20–30 minutes for the human eye to fully adapt from bright sunlight to seeing in complete darkness.  

The science behind using an eyepatch 
Why does it take so long to adapt to darkness, you may ask. That is because when you switch off the lights, the first thing that happens to your eyes is that your pupil gets bigger or dilates to let in more light. But this light is not enough to see in the dark. So, the chemical rhodopsin in your rods splits into a few other chemicals and sends a message to the optic nerve, allowing your eyes to process even the faintest of light. The problem is that the chemical rhodopsin isn’t produced in darkness. And therefore, it takes 20-30 minutes for your eye to recombine those chemicals again for proper vision. 

Now, if a pirate was fighting on the upper deck in the sunlight, then had to continue the fight under in the lower deck where it is usually pretty dark, it could take too long for their eyes to adjust, allowing him to see.  Now, here comes the science behind using an eyepatch. The eyepatch used to help in preparing one eye to see in the dark, so when they would go to the lower deck pirates could swap the eye patch from one eye to the other and see with the eye that has already adjusted to dim light. This would help them to instantly see in the dark.