Retinal detachment

The retina is the thin, light-sensitive film lining the back of the eye — the surface on which the image is built. It rests on the layer beneath it, which supplies it with oxygen and nourishment. A detachment is what happens when that film lifts away from the layer below: first at an edge, then further and further in. This condition has one feature that makes it easy to miss, far more often than it should be. It does not hurt. The eye looks white and calm from the outside, there is no fever, and the person decides to wait until Monday. Meanwhile the cells left without nourishment are dying, and once they are gone they cannot be brought back. Here it is not the severity of the symptoms that decides the outcome, but speed.

What the person actually notices

The complaints are almost always the same, and they come on suddenly — over hours, rarely over a couple of days:

• flashes of light: brief sparks or streaks of lightning off to one side, clearest in the dark and when the eyes move;
• a sudden shower of floaters — not the one familiar speck that has been drifting about for years, but dozens of new ones, like a swarm of midges or flakes of soot;
• a dark curtain or shadow creeping in from the edge of the visual field and moving towards the centre over hours or days; it can also feel like a missing piece of the picture;
• straight lines going wavy, letters swimming, faces blurring — this means the central zone is already involved;
• a sense of a veil, or of looking through cloudy water.

Checking yourself is simple: cover one eye, then the other, and look at a doorway or a window frame. The second eye usually fills in the missing patch, and until you cover the good eye you do not notice the loss at all.

A word about floaters. A great many people see drifting specks and threads, and on their own these are harmless. What is worrying is not that they exist but that they change: suddenly there are far more of them, flashes join in, a shadow appears. That change is what calls for an urgent examination.

Why this is counted in days

At the centre of the retina there is a small area we use for reading, recognising faces and picking out detail. The rest of the visual field is what we navigate by. While the detachment is confined to the periphery and the centre is still in place, sharpness of vision may be almost unchanged, and surgery done in time usually preserves it. Once the centre lifts, vision drops sharply, and even after flawless surgery it does not come back completely: the longer the centre went without nourishment, the less can be recovered. Hence the rule — do not wait.

There is a second reason to hurry. If the retina has not lifted yet and there is only a tear in it, the tear is sealed with a laser as an outpatient in a quarter of an hour. A detachment already means an operation in hospital. Sometimes only a few days separate those two scenarios.

See an eye specialist the same day, without waiting for a routine appointment, if:

• flashes have appeared suddenly, or floaters have multiplied sharply;
• there is a shadow, a curtain or a missing part of the visual field;
• vision has dropped or has become distorted;
• any of the above follows a blow to the eye or the head — even if at first it seemed to have caused no harm.

Separately: if vision in one eye disappears suddenly and completely, as though a light had been switched off, the problem may not be the retina but a blocked artery in the eye. And if the face droops at the same time, an arm goes weak or speech becomes muddled, that is a stroke. Both need an ambulance — across Europe the single number is 112 — and there the clock runs in minutes.

It is better not to drive yourself to the appointment: the pupil will be widened with drops, and for several hours after the examination you must not drive.

Why the retina comes away

The inside of the eye is filled with a clear gel, the vitreous. Over the years it shrinks and pulls away from the retina; this is called posterior vitreous detachment, and in itself it is not dangerous, although it is precisely what produces those flashes and floaters. For most people that is where it ends. But sometimes the gel, as it pulls away, catches the retina and tears it. Fluid then seeps through the tear underneath the film and undermines it, the way water works its way under wallpaper. This is the commonest mechanism by far.

The odds are higher if you have:

• short-sightedness, especially if it is severe: such an eye is longer than usual and the retina in it is thinner and stretched;
• passed the age of fifty;
• had eye surgery before, most often for cataract;
• had an eye injury, including one long ago;
• already had a detachment in the other eye, or blood relatives who have had one;
• thinned patches of retina found at an examination — these are called lattice degeneration.

There are two further routes by which the retina comes away without any tear, and they are worth knowing about. The first is traction: in advanced diabetic eye disease, strands of scar tissue grow inside the eye and pull the retina off its bed. The second is fluid gathering under the retina on its own: with inflammation inside the eye, with very high blood pressure, with severe pre-eclampsia late in pregnancy and — rarely, but this matters more than anything else here — with a tumour inside the eye. In adults that is usually a melanoma of the choroid; in small children, a retinoblastoma. This is why a detachment in which the doctor finds no tear is never left without the cause being established. And for the same reason, a white glow in a child's pupil in flash photographs, a squint that appears out of nowhere, or one pupil that is a noticeably different colour are all reasons to have the child seen by an eye specialist this week rather than at some point.

What happens at the appointment

The examination is straightforward, but it needs a widened pupil — otherwise the edge of the retina, which is where the tear usually hides, simply cannot be seen.

• First, drops that widen the pupil; they take about twenty minutes to work.
• Then an examination of the back of the eye through a lens, often with gentle pressure applied through the eyelid, which brings the far periphery into view.
• Optical coherence tomography gives a layer-by-layer cross-section of the retina and answers the key question: whether the centre is involved yet.
• If the inside of the eye cannot be seen at all — because of blood in the vitreous or a cloudy lens, for instance — an ultrasound scan of the eye is done.
• The other eye is always examined too, even when it is causing no trouble.

After the drops, everything is blurred and light is painful for four to six hours. Bring dark glasses and someone who can take you home.

How the retina is put back

The method depends on whether the retina has already detached, where it has detached and how far. The doctor decides after examining you, but it helps to understand the options in advance.

• Laser or freezing for a tear without detachment. Spots are applied in a ring around the tear; they turn into scar tissue and weld the retina to the layer beneath it all the way round. This is done as an outpatient, under anaesthetic drops, and takes minutes.
• A gas bubble. A bubble of gas is injected into the eye and presses the detached area back from the inside, while the tear is additionally sealed with laser or freezing. It does not suit everyone: it needs a small detachment in the upper part of the eye and a willingness to hold the head strictly in a set position.
• A buckle on the outside. A silicone band is stitched to the wall of the eye from the outside, indenting the wall slightly inwards to meet the retina. The eye itself is not opened. This approach is often chosen in younger people, whose vitreous is still dense.
• Vitrectomy. Through three microscopic openings the vitreous is removed, the fluid under the retina is drawn off, the retina is laid back down, the tear is sealed and the cavity is filled with gas or silicone oil to hold the retina in place until the scar is strong. Gas absorbs on its own over weeks; oil is removed later in a separate small operation.

Anaesthesia is more often local: an injection around the eye, with the person awake but the eye feeling nothing. A general anaesthetic is not always needed. People usually go home the same day.

A separate word on the gas bubble — this is the one prohibition that must not be broken. While gas is in the eye you must not fly or go high into the mountains: at altitude the bubble expands, pressure inside the eye shoots up, and sight can be lost irreversibly. Nor can you have an anaesthetic containing nitrous oxide — tell any doctor about this, dentists and anaesthetists included, before agreeing to a procedure. Ask on discharge exactly how many weeks your gas will last, and keep that date in mind.

The first weeks after surgery

The eye is red, waters, feels gritty under the lid and aches: all of that is expected and passes. Ordinary over-the-counter painkillers are enough for the pain; which one suits you is a question for your doctor or the pharmacy, particularly if you take anything else. The drops — usually an antibiotic and an anti-inflammatory, sometimes something to lower the pressure in the eye — are used exactly to the schedule and not abandoned the moment things feel better.

Vision stays cloudy for weeks, and that is not a sign of failure. With a gas bubble you first see a dark "horizon" that slowly sinks downwards — that is the bubble absorbing. If the doctor has prescribed a head position, keep to it: it is not a formality, whether the retina settles or not depends on it directly. It sometimes has to be held for up to a week, and it is, frankly, the hardest part of the treatment.

For several weeks you will have to put aside heavy lifting, swimming pools, saunas and eye make-up; rubbing the eye is off limits entirely. The exact timings, when you can drive again and when you can return to work, come from the surgeon: they depend heavily on what was actually done.

Go back to hospital straight away, without waiting for the planned check-up, if after the operation:

• the pain is getting worse and painkillers are not touching it;
• the eye has suddenly become very red or there is pus-like discharge;
• vision is worse than it was the day before;
• the shower of floaters, the flashes or a new shadow have come back;
• pain in the eye comes with nausea, vomiting and rainbow rings around lights.

About the outcome, honestly: a single operation puts the retina back in about nine cases out of ten, and the rest need a second procedure — which is neither rare nor a mistake. Vision recovers noticeably more slowly than the retina reattaches, so the result is judged after months. After a vitrectomy the lens clouds over sooner and more often, so many people have cataract surgery a year or two later; that is the expected course of events, not a complication. And the thing to carry forward: a detachment can happen again, and it can happen in the other eye, so the warning signs above are worth knowing by heart and the second eye is worth showing to a specialist regularly.

Online consultation

Let us be plain: the back of the eye cannot be examined through a screen, and a detachment is not diagnosed remotely. But in this particular subject an online appointment settles the question that in practice matters more than the diagnosis — how urgent this is. The doctor will go through what exactly you are seeing: long-standing harmless floaters, a posterior vitreous detachment with its flashes, or a picture that means travelling today. They will tell you where to go and what to take with you. After surgery, an online appointment is a convenient place to go over the drop schedule, how long the restrictions last, the question of flying with a gas bubble, and to work out whether how you feel is within the normal range or whether the surgeon should see you sooner than planned. If what you describe looks like a detachment, the doctor will send you for a face-to-face examination — and that is the right outcome of the consultation, not a brush-off.

This material is for information only and does not replace medical advice.