It was probably the first thing you noticed as a kid, jumping excitedly into the pool for the first time after learning how to swim, ready to take on the ocean and all of its underwater creatures. But then you realise – you can’t see underwater without your goggles. Everything is blurry. You end up accepting this is as a fact, either closing your eyes underwater, wearing goggles, or keeping them open and ending up with sore red eyes after your swim.
But why does the water look blurry when you open your eyes underwater? Why aren’t we able to see the same as we can see above water? And for the fearless ones who open them anyway – how do you get rid of blurry eyes from swimming?
Why do things look blurry underwater?
Understanding the reason why things don’t look as crisp underwater requires a little bit of a science lesson. We love science lessons here at Ninja Shark (when they’re related to snorkelling, anyway…) So basically, the reason we can see anything we do is because of light. That should be an obvious one. Light rays travel through the air all the time, and they bend as they travel between one medium and another. The amount of bending that light does depends on this thing called ‘refractive indices’. Let’s not worry about that too much.
The point is, water has nearly the same refractive index as the human cornea (that’s your eye), meaning there’s not much room for the light rays to bend. This basically prevents the eye from being allowed to focus, making things look blurry. What’s happening here is that light rays reach the retina before they’re able to bend into a focused image. It’s pretty much the same as having a projector placed too close to the wall, or the camera too close to your face. There’s not enough space for the image to focus.
How do goggles and masks allow us to see underwater?
So how come we can see underwater when we wear goggles or a snorkel mask? Good question! What’s happening here is that a snorkel mask will create a layer of air between the human eye and water. Air has a different refractive index to both water and the human eye, giving light ample space to bend and create a focused image. We can always see if there’s air in front of our eyes, can’t we?
Why does my vision improve with a snorkel mask?
A lot of people feel that their vision is vastly improved when they wear a snorkel mask underwater. Things look crystal clear, and sometimes even better than they do above water. What’s the reason for that? Well, flat snorkel masks offer a superior field of vision, and often magnify objects by up to 33%. Things can also look as though they are up to four times closer than they actually are. So basically, everything looks bigger and closer to you, giving you the impression that your vision has been improved.
How do you get rid of sore eyes after swimming?
So, you’ve realised that you can’t see properly underwater yet you’ve decided to go for it anyway. You do you, buddy! If you’re experiencing red, sore, or irritated eyes after going for an open-eyed swim without your goggles, here’s how you can find relief:
- Wash your eyes out with clean water – Fill a small bowl with lukewarm water. Blink open and close one eye at a time 5 times in the water.
- Use a saline solution – This will restore moisture to your eyes, which are likely dry and scratchy. You can find saline solution eye drops at any pharmacy, follow the instructions and cry the soreness away.
- Apply a cold compress – Wet a cloth or rag under cold water and place it over your closed eyelids for a few minutes. This should help ease any stinging, swelling, and irritation. If the rag warms up quickly then wash it again with cold water and continue.
- Use tea bags – Tea bags can help ease inflammation and reduce swelling. Soak two tea bags with cool water, and place them over your closed eyelids. Keep them there until they reach room temperature. If your eyes still feel sore then repeat.
- Use cucumber – Cucumbers have cooling properties that can soothe irritation and restore moisture in dry, sore skin. Take a cooled cucumber and cut off two thick slices, placing them over your closed eyelids. It’s basically like a day spa!