When you’re underwater, the light passes from air to water which slows down its speed and causes the light rays to bend. This phenomenon is called refraction which causes objects to appear 33% larger or closer by a ratio of 4:3 underwater. This means that an object that is 4 meters away will look as if it’s only 3 meters away from you when you’re submerged. Although this might seem favorable for those with not-so-perfect vision, it’s not enough to help people with poor eyesight and requires more than a small amount of correction.
Don’t worry, you can still go diving even if you don’t have a 20/20 visual acuity (sharpness of vision). An easy way for correcting vision underwater is by wearing contact lenses. If you’re a contact lenses wearer and excited to go diving to witness the oasis under the sea, you’ll be glad to know that you can safely dive with your contact lenses.
Safety diving tips for contact lens wearers
There are essentially two kinds of contact lenses: hard and soft. Although it’s possible to go diving with any of the two, it is highly recommended that you use soft contact lens underwater.
If you dive with hard lenses, chances are you might experience blurry vision at some point. The reason for this is that the eye absorbs nitrogen and when you make your way underwater, the nitrogen slowly escapes the eye. The hard lenses trap the nitrogen creating tiny bubbles that form between the lenses which lead to a cloudy vision. You’re also prone to dryer eyes if you use hard lenses underwater; making you want to blink more often than normal. Compared to soft lenses, the hard ones are usually smaller and there’s a bigger chance of them falling out especially when clearing the mask which can be a big predicament.
Soft lenses, on the other hand, allows air to pass through the lenses thus, preventing bubbles. The eyes will not feel dry while you’re diving unlike when you wear the hard version. Since soft lenses have a slight advantage in size, you can simply close your eyes to hold the lens inside if you float the mask.
You may also use disposable contact lenses which you can easily dispose and change into a new one at the end of your dive.
It is important to inform your dive buddy that you are wearing contact lenses so that if the unlikely situation occurs and you lose your contacts, your buddy can guide you along the way or back to the boat.
As mentioned earlier, you may blink more frequently during a dive, especially if you’re wearing hard lenses. One way of keeping your lenses moist and prevent irritation is to use lubricating drops in your eyes before and after diving. You can also take advantage of the surface interval (SI) – the time spent by a diver out of the water in between dives – to rinse out your lenses with fresh cleaning solution. By doing so, you can wash away the presence of salt water that could irritate your eyes.
If you’re not comfortable about diving with contact lenses, there are other ways to still enjoy diving even if you have poor vision. You can get corrective masks from optical shops that specialize in prescription lenses for dive and snorkel masks. If you’re diving in Mexico, you can coordinate with local dive shops to order one.
Customized Prescription Mask
If you’re a certified and frequent diver, you can consider investing in a prescription mask. The entire lens of your mask is replaced with a glass that is customized to your prescription. A customized prescription mask can be quite expensive but it has better fit and gives excellent results.
Another alternative is using a special bonded lens that offer the same correction as your eyeglasses. They come in perfectly flat fronts which are glued onto the inner side of the glass of your dive mask. It’s flexible so it can be attached to a variety of masks. However, if your correction is large (more than five diopters) and normal glasses are used, it will turn out as “coke bottle” glasses. To reduce the thickness and avoid this effect, you can opt for hi-index glass. You can inquire at some local dive shops and optical stores that might provide this kind of service. It can be fairly expensive but not as much as a prescription mask.
If you have a relatively good distance vision and only require reading glasses, you can request for special reading lenses. These can be glued strategically near the bottom of your mask so that you can read your gauges. This option may not be as reliable since the glasses can move or worse, get knocked out of position by the water surface tension.
Looking for a simple and less expensive alternative? You can buy the mask and the dive store can replace the glass with prescription lenses (available in half-diopter increments) that are close to your glass prescription. The vision correction may not be as perfect compared to an actual prescription mask but it works if you don’t need high astigmatic correction, bifocals, prism, etc.
Consult your optometrist
These are just suggestions to help you dive and appreciate the detail of the beautiful underwater realm but it’s always best to check first with your optometrist regarding the safety of diving with your contact lenses or corrective mask.