Seeing Sharp On and Under the Water: Glasses, Lenses and Water Sports in Bali

In Bali the sea is never far. Surf at first light, snorkelling in the afternoon, the boat across to Nusa Penida at the weekend. If you wear a correction, the same question comes back every time, in Canggu as in Sanur: how do you see sharp without leaving your pair at the bottom of the ocean.

We get asked this every day, and it is the question optician blogs cover least. Most advice assumes you live far from water. Here it is the opposite. So let us take the subject properly, because there are two distinct problems hiding behind one question, and the answers are not the same.

In the water, on the water: two problems with nothing in common

In the water, your problem is sharpness. Reading the wave coming, finding your things on the beach, recognising a face. Light comes second.

On the water, in a boat or sitting on a board between sets, the problem becomes light. The surface throws part of the sun's radiation straight back at your eyes, on top of what comes from the sky. You squint, you tire, you read the swell less well.

Confusing the two means buying the wrong pair. Let us take each case.

Swimming with a correction: what an optician will actually tell you

The most common answer is still the soft daily lens. It corrects, it does not move, and you throw it away on the way out. But one rule comes back every time, in Canggu as in Ubud, and it is not negotiable.

A lens is a microscopic sponge sitting on the cornea. Put it in contact with sea water, a pool or a rice field and it holds on to the micro-organisms in there, keeping them against the eye for hours. That is the mechanism behind microbial keratitis, an inflammation of the cornea. The one worth knowing by name is Acanthamoeba, an amoeba that lives in fresh water, swimming pools and tap water, and that shrugs off the chlorine levels used to treat drinking water. It is rare. It is also extremely painful and can take a year to treat. The same rule applies on dry land: never rinse or store a lens in tap water, and if water gets into your eye with lenses in, take them out and bin them. Our guide to contact lens hygiene covers the daily handling rules.

We stock the lenses themselves, dailies, monthlies and torics for astigmatism, in Canggu, Ubud, Sanur and Seminyak. Never worn any before? We show you how to put them in, take them out and keep them clean before you leave the store.

Two clean ways to do it:

• Daily lenses under watertight swimming goggles. Water never touches the lens. You take them out and bin them when you come out. This is the safest method.
• A prescription dive mask, or prescription swimming goggles. No lens at all, the correction sits in the mask itself. For regular snorkelling it is the most comfortable route by far. We do not make them at Maison Mata and we will not pretend otherwise: order one from a dive specialist, and come to us first for the exact correction to put in it.

A mask does something else on its own. Open your eyes underwater and everything is blurred, whatever your sight: water bends light almost exactly like your cornea does, so the eye loses around 43 dioptres of focusing power, far more than any eye can make up. The mask puts a layer of air back in front of the eye and hands that power back. And because flat glass sits between water and air, things look roughly a quarter closer and a quarter to a third bigger than they really are. It does not replace a correction, but it explains why some short-sighted people read the fish better than the sign on the warung.

On a boat: why polarised is not a gadget

Light bouncing off a flat surface, water in particular, comes back largely polarised: a big part of it ends up vibrating in the same horizontal plane, and the effect peaks when the sun sits fairly low over the water. A polarised lens carries a filter that blocks precisely that plane. The white veil drops away and you get back the relief, the colours, sometimes even the bottom.

On the water, the gap with a plain tinted lens is obvious, far more than in town. It is also a real safety gain if you are steering a boat or watching for a set. We go into the mechanism in polarized lenses or UV protection.

Two useful clarifications:

• Polarisation and UV protection are two different things. A lens can be polarised without filtering ultraviolet properly, and the reverse is true too. You want both.
• For full Balinese sun bouncing off water, category 3 is the right level. Category 4 lets through less than 8% of the light and is built for glaciers and high mountains. It is too dark to read a traffic light, which is why the European standard requires it to carry a crossed-out car symbol. The full scale is in sunglasses lens categories, from 0 to 4.

The frame that holds, and survives the salt

A beautiful pair that does not hold is a lost pair. A few simple principles, learned from repairing glasses that came back from the beach.

• A floating cord, not a decorative one. If it does not float, all it buys you is a clear view of your pair sinking.
• A light, flexible frame. On the water, acetate takes knocks better than fine metal, which bends out of true at the first snag.
• Nose pads that grip. Wet skin and sunscreen make an ice rink. Silicone pads change everything.
• No exposed screw hinges if you can avoid them. Salt gets in and seizes the mechanism.

After the session: three gestures, two minutes

Salt does not forgive. It crystallises as it dries and attacks both the lens coatings and the screws.

1. Rinse in lukewarm fresh water, never hot, as soon as you are back. Without rubbing.
2. A drop of neutral soap on your fingertips, then rinse. Soap lifts the sunscreen, which is far more aggressive on coatings than the salt itself.
3. Dry with a clean microfibre, never a t-shirt or a beach towel, both of which carry sand.

And never leave a pair on the dashboard of a car or a boat. Acetate is a thermoplastic: it softens from around 60 degrees, which is exactly how we reshape a frame at the counter with a warm-air blower. A dashboard in the sun passes 65 degrees within the hour, with nothing holding the frame in place, and it keeps whatever shape it cools down in. Same reason a frame worn daily here needs realigning two or three times a year. More on the local climate in your glasses in the tropics.

What we recommend, depending on how you use the water

• Regular surfing with a correction: dailies under swimming goggles, or nothing in the water and a polarised prescription sun pair for the rest of the day. We cover those in prescription sunglasses in Bali.
• Snorkelling: dailies under a watertight mask, or a prescription mask ordered from a dive specialist. We give you the correction to order it with.
• Boat, fishing, a day at sea: polarised category 3, floating cord, acetate frame.
• Beach and pool without swimming: your usual sun pair is fine, with the rinsing ritual.

The best pair for the water is not the most technical one. It is the one you are still wearing at the end of the season.

If you are torn between these options, come to Canggu, Ubud or Sanur. An optometrist checks your correction, we look at how you use the water and how a frame sits on your face, and we settle it in a few minutes. Faster than three evenings of research online.

This article is informative and does not replace medical advice. In case of redness, pain, blurred vision or unusual light sensitivity after contact with water, remove your lenses and consult a health professional without delay.