Red eye in Vietnam: conjunctivitis, contact lenses and the signs that mean an eye hospital

Red eyes are one of the things we are called about most in the hot months. The great majority of them are harmless. Vietnam runs sizeable waves of viral conjunctivitis that go through offices, hostels and kindergartens in a fortnight. A tropical summer adds dust, air conditioning, salt water, chlorine and sunscreen running into eyes on a boat.

A small number are something else entirely. In those the clock matters, because the cornea can scar permanently. Fortunately the two groups separate on a short list of features, mostly to do with pain and vision. That list is the second section below, and it is the part of this page worth reading before you need it. Looking at your own eye in a phone camera is not an examination, and nothing here identifies what you have.

Pain and blurred vision are not conjunctivitis

Conjunctivitis is gritty, itchy and sticky. It does not genuinely hurt and it does not reduce sight beyond what wiping away discharge fixes. Anything on this list points at the cornea, the inside of the eye, or pressure within it. Go to an eye hospital or the nearest emergency department straight away, not in the morning. Ring 115 if it comes with vomiting, a severe headache or an injury:

• Real pain in the eye, rather than irritation — a deep ache or a feeling of something embedded
• Vision that has dropped, blurred, or developed a shadow or floaters that are new
• Strong sensitivity to light, so that a bright room makes the eye clamp shut
• A white or grey spot visible on the surface of the eye, which may be a corneal ulcer
• Redness concentrated in a ring right around the edge of the iris rather than spread across the white
• A red painful eye in someone who wears contact lenses — treat that as urgent by default
• Any penetrating injury, or a chemical splash, or a high-speed particle such as grinding or strimming debris
• A severely painful red eye with headache, nausea and halos around lights, which can be acute glaucoma
• A red eye in a newborn, or in anyone whose immune system is suppressed

If a chemical has gone into an eye, start rinsing immediately with the cleanest water available. Keep going for a long, uninterrupted stretch — twenty continuous minutes under a gentle flow, holding the lid open. Before you do anything else, including looking up what the chemical was. Then go to hospital, taking the container if you have it.

Three kinds of conjunctivitis, and how they differ

Sorting these out changes what gets used, which is why guessing wastes days.

Viral conjunctivitis is the one that sweeps through a group. It usually starts in one eye and crosses to the other within a few days. The discharge is watery and the eye feels gritty. There is often a tender lymph node in front of the ear, and a cold or sore throat may have come first. It gets worse for several days before improving and the whole business can run two weeks. Antibiotic drops do nothing to it.

Bacterial conjunctivitis produces genuine pus: yellow or green discharge, lids stuck together on waking, frequently both eyes. Many cases settle without treatment, and drops shorten the sticky phase.

Allergic conjunctivitis is itchy above all else, with puffy lids and a stringy, clear discharge, both eyes equally, often seasonal or triggered by dust and air conditioning. Scratching makes it worse in a loop that is hard to break.

Contact lenses and water do not mix

This is the single most consequential paragraph on the page. A contact lens worn in the sea, a river, a pool or a shower, or rinsed in tap water, is the standard route to the two eye infections that destroy sight. Pseudomonas can ulcerate a cornea within a day. Acanthamoeba, a water-borne organism, causes a protracted, agonising keratitis which is difficult to treat and leaves scarring.

Warm tropical water is friendlier to both organisms than cold water. And the behaviour that causes it is completely ordinary — a snorkelling trip with lenses in, a shower without taking them out, topping up a case with tap water because the solution ran out on an island.

• Take lenses out before any water: sea, pool, river, waterfall, shower, hot spring
• Prescription goggles or a prescription mask solves the diving and swimming problem properly, and daily disposables you throw away immediately afterwards are the pragmatic second choice
• Never rinse lenses or a case in tap water, and never top up old solution. Bring more solution than you think you need, because the brand you use may not be stocked where you are going
• Do not sleep in lenses that were not designed for it, and do not sleep in them at all after a day in the water
• If a lens-wearing eye becomes red and painful, the lens comes out and stays out, and you are seen that day. Keep the lens and the case to bring with you, because they can be cultured

Steroid drops bought over a counter

Eye drops containing steroids are sold without a prescription in much of Southeast Asia, often in combination bottles, and they are sometimes handed over for a red eye. They take the redness away quickly, which is exactly the problem.

On a viral or bacterial surface infection, steroids suppress the inflammation while allowing the organism to multiply. On a herpes simplex infection of the cornea they can turn a treatable ulcer into one that perforates. Used for weeks they also raise the pressure inside the eye and can cause cataract.

The rule for a traveller is simple. Do not put a steroid drop in an eye unless someone has examined it with a slit lamp and prescribed it. If you are already using a drop and do not know what is in it, bring the bottle to the consultation. The ingredient list is on it, and the name is usually the clue.

What makes it spread so fast

Viral conjunctivitis is adenoviral in most waves, and adenovirus survives on surfaces for days and resists hand gel better than most viruses. Towels, pillows, phone screens, door handles and the shared mascara in a hostel bathroom do the work.

Self-care during an outbreak is unglamorous and effective. Hands with soap and water rather than gel, a towel that nobody else touches, no eye make-up, change the pillowcase, and leave the pool alone while it is active. People remain infectious while the eye is still weeping, which is longer than most assume.

The lid problems that are not conjunctivitis

A stye is a tender lump at the lash line, with a red, swollen lid. Warm compresses several times a day, and it drains on its own.

The one that is not benign is preseptal or orbital cellulitis. The lid and the surrounding tissue become swollen, hot and red, and the eye may ache or struggle to move. Swelling that is closing the eye, a fever, pain on moving the eye, or double vision means hospital the same day. Infection behind the lid is in a different compartment, with a different outcome.

Sun, salt and sand on the coast

Ultraviolet light reflected off water burns the surface of the eye. A long day on a boat without sunglasses produces photokeratitis that evening — both eyes gritty, streaming, intensely light-sensitive, and painful for a day or so. It settles on its own. Sunglasses with genuine ultraviolet filtration and a brimmed hat prevent it, and cheap market sunglasses that darken without filtering are arguably worse than none.

Salt water alone irritates rather than infects. Sand in an eye is different. A grain under the upper lid scratches the cornea with every blink, and an abrasion that keeps being reopened is how travellers end up with an infection on top of it. A foreign body that cannot be flushed out with a steady stream of clean water is removed properly, with the eye numbed, rather than with a cotton bud in a mirror.

One specific warning for a motorbike. A high-speed insect or stone in an unprotected eye is a potential penetrating injury regardless of how trivial it feels at the time, and a visor or glasses are cheap in comparison.

What a clinician coming to you can do

• Measure vision properly in each eye, which is the number that decides urgency more than anything else
• Examine the surface with a torch and with fluorescein stain, which reveals abrasions and ulcers that are invisible to a phone camera
• Evert the upper lid to find the grain of sand that is causing a scratch that will not settle
• Choose a treatment on the pattern rather than on the colour, and identify a bottle you have already been using
• Refer straight to an eye hospital when the picture is corneal, pressure-related or a lens-associated keratitis, with a call ahead and a letter in English
• Issue an itemised invoice and a written report for a claim, including the vision recorded at the visit

Carry this away

Itchy, gritty and sticky with normal vision is almost always conjunctivitis, and most of it needs hygiene rather than drops. Painful, light-sensitive, or any drop in vision is an eye hospital today. Lenses never go into water, and a steroid drop never goes into an eye that nobody has examined.