Diving with contact lenses: hard or soft, what to know

The two-lens problem

There are essentially two families of contact lenses in everyday use.

Soft lenses sit on the cornea with a thin film of tear fluid underneath and conform to the eye’s curvature. They are permeable enough that small amounts of nitrogen dissolving in tear fluid don’t pose a meaningful problem.

Rigid lenses sit on the cornea with a thicker layer of tear fluid underneath. Under increasing ambient pressure, dissolved nitrogen can come out of solution in that fluid layer and form tiny bubbles between the lens and the cornea. Divers report this as a sandpapery feeling, halos around lights, sudden blurred vision, or a lens that pops off entirely on ascent.

Soft lenses: the practical default

Most people wearing contact lenses today are in soft lenses — hydrogel or silicone hydrogel monthly, fortnightly, or daily disposables. The diving experience is straightforward.

• Put them in before kitting up. Hands are cleaner before you’ve handled gear, tank straps, and shore-side mess.
• A pair lasts a full dive day with no special handling.
• If you flood your mask, close your eyes before clearing. Most lens losses happen with the eyes open during clearing, not from water contact itself.
• Saline rinse and re-seat if a lens shifts during the dive — you can do this between dives at the surface.
• Sleep without them. Even extended-wear lenses are better off out overnight on a liveaboard.

What you do not do: rinse contacts with tap water. We’ll get to why in a moment.

Hard and RGP lenses: the awkward case

If you wear rigid gas-permeable lenses, talk to your optometrist before booking a dive trip. The mechanism is straightforward:

1. At the surface, the tear film under the lens is in pressure equilibrium with the atmosphere.
2. As you descend, the gas dissolved in the tear film stays dissolved at higher partial pressure.
3. As you ascend, that gas can come out of solution into bubbles between the lens and the cornea.
4. The bubbles are small enough not to be dangerous, but big enough to be uncomfortable and to distort vision.

In practice the symptoms are usually mild: a gritty feeling on ascent, brief blurred vision, sometimes a halo effect around the boat’s deck lights when you climb back aboard. Most divers in RGP lenses learn to handle it. Some find it intolerable and switch to soft lenses for diving only, with their optometrist’s input.

A more concerning rare event is the lens dislodging entirely on ascent due to the bubble pushing it off. If this happens at depth, accept the loss, surface safely, and replace the lens topside.

Scleral lenses — large rigid lenses that vault over the cornea and rest on the sclera — sit on a substantial fluid reservoir under the lens. Bubble formation in that reservoir is a real concern. If you wear sclerals for keratoconus or post-surgical correction, get specific input from your fitter before diving.

The acanthamoeba problem (and why tap water is banned)

Acanthamoeba is a free-living amoeba present in fresh water, soil, and air worldwide. In most contexts it doesn’t bother humans. In contact lens wearers, it can cause acanthamoeba keratitis — a corneal infection that is painful, slow to diagnose, slow to treat, and has caused permanent vision loss in published case series.

The route in is contact lens contamination with non-sterile water. The classic case is a swimmer who wore lenses in a hot tub or a contact lens wearer who rinsed their lenses with tap water. The risk is small per exposure but the consequence is bad enough that ophthalmologists worldwide say the same thing: never rinse contact lenses with anything other than sterile saline or proper contact lens solution.

Rules for divers:

• Never rinse contact lenses with tap water, bottled water, pool water, or seawater.
• Keep a small bottle of sterile saline on the boat. The travel-size 100 ml bottles are perfect for a day dive.
• If you drop a lens on the deck, the right call is usually to bin it and put in a fresh one rather than rinse and re-insert.
• This is the single biggest reason to dive in daily disposables: there is no lens to clean overnight and no temptation to use the wrong fluid.

The risk on a single dive trip is genuinely small. The risk over a lifetime of regular diving with sloppy lens hygiene is meaningfully not.

Daily disposables: the recommendation

Most dive doctors who get asked about lenses end up recommending daily disposables for diving. The reasoning:

• One pair per dive day. No overnight care, no cleaning fluid to forget on a liveaboard.
• Lose one underwater? Open a fresh blister pack on the boat. A 30-pack typically costs €25–35 and lasts a long dive trip.
• No bacterial buildup risk from poor cleaning.
• Easier travel — no large solution bottles to take on aircraft.

If you don’t normally wear dailies but you dive regularly, ask your optometrist for a daily-disposable prescription specifically for dive trips. Most will write one without issue.

When you should not wear lenses for diving

Some conditions and circumstances move the needle from “fine” to “don’t.”

For LASIK specifically: dive doctors typically want a written sign-off from the surgeon. The corneal flap is structurally stable within weeks but mask squeeze can theoretically displace it within the first few months. Don’t push this — it’s the kind of injury that’s recoverable but expensive and ruins a trip.

Prescription dive masks: the alternative

If contacts are not for you — eye dryness, recurring irritation, RGP wearer who hates the bubble feeling — a prescription dive mask is a real solution.

Two flavours exist:

• Drop-in corrective lenses. The mask has standard lens-shaped holes and you buy stock-strength replacement lenses in the diopter you need (e.g. -3.50 / -3.00). Available in roughly 0.5-diopter steps from -1.0 to -8.0. Around €60–100 in total. Practical and fast.
• Custom prescription mask. An optician grinds custom lenses for your specific prescription including astigmatism correction and bonds them into the mask. Around €250–450. Best for divers with significant astigmatism or unusual prescriptions.

Both are perfectly legitimate dive masks — they don’t compromise the seal or the fit, they just have your prescription built in. Most reputable dive shops can either supply them directly or refer you to an optician who does.

Pros of a prescription mask: you can see when the mask is off (e.g. on the surface, on the boat). No risk of losing a contact in the water. No tap-water risk.

Cons: it’s your prescription frozen in time — you can’t update it as easily as new contacts.

Practical setup on the boat

A reasonable lens kit for a dive day:

• One spare blister pack of dailies in a dry-bag on the boat
• 100 ml bottle of sterile saline
• A mirror (most boats have one in the head; otherwise a small one in your kit)
• Eye drops for the dry-eye feeling after a windy surface interval — single-dose preservative-free are best

Things you do not need: complicated cleaning solutions, lens cases (if you’re on dailies), or anti-fog drops touching your eyes.

What to do if a lens goes missing underwater

It happens. Mask floods, eyes open during clearing, lens washes away.

1. Don’t bolt. A lost lens is uncomfortable, not dangerous. Vision in one eye is enough to see your buddy and the bottom.
2. Signal your buddy. They can stay close and help with navigation.
3. Don’t try to swim around looking for it. Lenses in 18 m of water on a sandy bottom are gone.
4. End the dive when reasonable. If you can do a normal safety stop and surface, do so. Don’t compromise the dive plan for a lens.
5. Replace topside. Fresh pair from your spares; sterile saline rinse the eye if it’s irritated.

If you lose the same lens repeatedly, the fit is probably wrong and the optometrist needs to know. A correctly-fitted soft lens almost never falls out from a mask flood alone.

Quick decision framework

• Wear soft daily disposables? Continue. Bring spares.
• Wear soft monthly or biweekly? Continue. Bring solution, a case, sterile saline.
• Wear rigid gas-permeable? Talk to your optometrist; consider switching to soft for diving.
• Wear sclerals? Specific case — get input from your fitter and a dive doctor.
• Don’t wear contacts but need vision correction underwater? Get a prescription mask.

Contacts plus a mask works for the great majority of glasses-wearers. The lens type, the hygiene, and what you do when something goes wrong matter more than whether or not you wear them at all.