Cataract
Lasering posterior capsule opacification: the YAG capsulotomy, when vision becomes hazy again
Months to years after cataract surgery, vision becomes hazy again in some of those operated on — colours go flat, headlights flare, reading needs more light. Usually there is no new cataract behind it but posterior capsule opacification: the wafer-thin capsule in which the artificial lens sits clouds over. It is treated with a short laser procedure in the consulting room, the YAG capsulotomy — as an outpatient, without an incision and without the eye being opened.
What posterior capsule opacification is — and why it arises
The operation was behind you, vision became clear, and you had put the matter to rest. And now a haze is settling over it again: colours look flat, you need more light for reading, headlights dazzle more at night than they used to. It feels like it did back then — and many people therefore think first that the cataract has come back.
It has not. To understand what is happening instead, it helps to look at what happens to the lens of the eye in cataract. The natural lens sits in the eye inside a very thin, transparent envelope, the capsular bag. In cataract surgery with an artificial lens the clouded lens is removed from this bag, the artificial lens goes in — and the capsule is deliberately left in place, because it holds the new lens where it belongs. Its back wall then lies as a clear film directly behind the artificial lens, in the path of the light.
That is exactly where posterior capsule opacification takes place. Individual lens cells stay behind in the capsular bag after the operation; they can multiply and grow across the clear back wall. The film thereby becomes cloudy, in places also wrinkled — and what previously passed through smoothly is now scattered. It is not the lens that has clouded over again but the window behind it. That takes time: months to years after the procedure, rarely sooner.
In reports and doctors' letters you will meet several words for it. Alongside posterior capsule opacification you will sometimes also find secondary cataract or capsule clouding. The same thing is meant every time. The name 'secondary cataract' is misleading, and that is the reason why we speak throughout here of 'posterior capsule opacification': it is not a second cataract, because the lens that could get one no longer exists.
Why posterior capsule opacification is not a surgical error
That is the question that almost always comes second in the consulting room — usually put cautiously: did something go wrong during the operation? No. In some of those operated on, the capsule clouds over months to years later. That is a known course after cataract surgery, no sign of an error, no consequence of your having asked too much of yourself, and no indication that the wrong artificial lens was chosen.
Nor does it mean that the artificial lens would have to be exchanged. It stays where it is. What is treated is solely the clouded capsule behind it, and with a laser rather than an incision. Anyone who still has the explanation given before their own operation in mind will remember: posterior capsule opacification is named there as a possible later course. In some consent forms and information leaflets it appears under complications, in others under the possible course — the same thing is meant both times, and neither wording says that something went wrong in your operation.
And it is not an emergency. It comes on slowly, it does not hurt, the eye does not turn red. You have time to arrange an appointment unhurriedly. What must not wait is something else: flashes of light together with many new black dots, a shadow moving in from the side into the field of vision, rapidly worsening vision or a red, painful, light-sensitive eye — even when you do not feel sick. These signs need assessing the same day — outside consulting hours through the ophthalmic emergency service or the emergency department of an eye hospital.
An emergency that comes before even that: A sudden, complete loss of vision in one eye — particularly together with headache, pain on chewing or difficulty with language and speech, and signs of paralysis — does not belong in our consultation but in an emergency department, immediately: call the ambulance (144). Behind it can be a vascular occlusion or a vascular inflammation, where minutes and hours count.
Symptoms: how you notice posterior capsule opacification
The hallmark is the repetition: the symptoms are the same as before the operation, only this time they come from a different layer. They begin insidiously, often over weeks to months, and often become noticeable only on comparison — driving at dusk, reading in the evening, looking at a face against the light.
- A haze over everything, as though through a slightly misted pane
- Flat colours and contrast — white looks greyed, outlines soft
- More glare against the light, in sun and from headlights; driving at night becomes tiring
- More light for reading needed than six months ago
- Double or shadowed outlines in one eye, which stay even when you cover the other eye
- No pain, no redness — and no sudden deterioration from one moment to the next
Posterior capsule opacification affects each eye separately. Where both eyes have been operated on, one can become troublesome markedly earlier than the other, and the difference is often noticed only when one eye is covered. Anyone who instead reaches first for new glasses usually finds quickly that the lenses do not solve the problem — the clouding is not in the glasses but in the eye. What makes sense is therefore not the route via a stronger correction but having your visual acuity measured by an ophthalmologist, at which the eye itself is looked at as well.
Not every return of cloudy vision is posterior capsule opacification
After cataract surgery, posterior capsule opacification is the obvious explanation for declining vision — but it is not the only one. The comparison below is therefore not a self-test but an aid to the conversation: it shows which observations fit posterior capsule opacification and which point elsewhere.
| What you notice | More likely posterior capsule opacification | More likely something else |
|---|---|---|
| Onset | Insidiously over weeks to months, months to years after the operation | Suddenly, from one day or one hour to the next |
| Nature of the disturbance | An even haze over the whole picture, flat colours | A dark patch in the middle of the image, straight lines distorted |
| Glare | Backlight and headlights flare, driving at night becomes hard work | Coloured rings around lights together with eye pain, a red eye and nausea point to an acute rise in pressure — have it assessed at once |
| Pain and redness | None. Posterior capsule opacification does not hurt and does not make the eye red | Pain, redness and light sensitivity point to inflammation — that needs examining the same day, even without nausea |
| Over the day | Largely unchanging, slowly increasing | Fluctuates over the day, briefly better after blinking or drops |
| Dots and flashes of light | Do not belong to the picture of posterior capsule opacification | Many new black dots, flashes of light or a shadow from the side: have it assessed the same day |
What can lie behind the right-hand column are conditions that have nothing to do with the artificial lens and occur independently of posterior capsule opacification: age-related macular degeneration (AMD) at the point of sharpest vision, a disturbed tear film in dry eyes, which makes visual acuity fluctuate over the course of the day, or conditions of the retina and vitreous. Also common is a posterior vitreous detachment, which brings new floating dots and streaks with it and at first feels similar for those affected.
That cannot be told apart at the kitchen table but at the slit lamp: there it can be seen directly whether the capsule behind the artificial lens is clouded — and if so, whether that clouding really lies in the visual axis and explains the symptoms. If you are unsure, the short route is the better one: Request an appointment for an assessment online.
The YAG capsulotomy: how the treatment works
Treating posterior capsule opacification is not a second operation. A laser places a small opening in the clouded capsule behind the artificial lens, so that the light passes through there unhindered again. The medical name for it is YAG capsulotomy — 'capsulotomy' means nothing other than 'opening the capsule', and YAG is the crystal in which the laser beam is produced; the active element in it is neodymium. No incision in the eye is needed, nothing is removed and nothing is exchanged, and the eye is not opened. The procedure takes place as an outpatient in the consulting room, not in the operating theatre.
When treatment happens — and when not yet
The trigger is not the finding alone but everyday life: treatment follows when the clouding troubles you when reading, at the wheel, at the screen or at work, and the examination shows that it also explains those symptoms. If the capsule is only faintly clouded and you hardly notice anything of it, nothing has to happen — posterior capsule opacification is not treated because it is there but because it is troublesome. A second appointment in a few months' time is a possible answer too.
There is one exception. If the clouding blocks the view of the retina, so that a condition there can no longer be assessed or treated, the capsulotomy is worthwhile even when you yourself notice little. That applies above all to eyes that are already being checked or treated regularly because of the retina — for instance with age-related macular degeneration or with retinal changes caused by diabetes. There it is not about your visual comfort but about our being able to see what lies behind the capsule.
Before the procedure
First comes the examination: visual acuity, assessment at the slit lamp and a look at the posterior segment of the eye, so that the clouding is not covering something else. Then come the drops — anaesthetic drops, and depending on the findings ones that dilate the pupil, so that the capsule can be seen properly. Both need time to work, and the dilation is the reason why you should not drive yourself after the appointment. You do not have to come fasting, and no general anaesthetic is needed either.
The procedure itself
You sit at a device resembling the slit lamp you have already been examined at, with your chin and forehead on the rest. A contact lens is usually placed on the eye, with which the laser beam is focused precisely on the capsule; at the same time it holds the eyelid open. Then come short laser pulses: you see flashes of light and hear a soft clicking. The procedure is regarded as painless; at most a sensation of pressure from the contact lens is felt. It is short — markedly shorter than the preparation that goes with it. Referring physicians who see posterior capsule opacification in their patients will find the routes to us under Referring physicians.
What to expect afterwards
Directly after the procedure vision is usually still blurred — that comes from the dilating drops and from the gel used with the contact lens, not from the laser. As long as the pupil is wide, everything glares more; sunglasses make the journey home more comfortable. What the laser does is narrowly bounded: it takes the clouding out of the visual axis. What it does not do: influence a retina, an optic nerve or a disease of the macula. How clear your vision becomes afterwards therefore depends on what else behind the capsule has a say — and that is exactly what we looked at beforehand.
Many people notice, in the first few days, floating dots or flecks in the field of vision. These are particles of the opened capsule drifting in the vitreous; they move along with your gaze and, experience shows, are noticed less as time goes on. To be distinguished from that is the sudden swarm of many new dots, often together with flashes of light or a shadow from the side — that is not a normal course after the treatment but a reason to call at once.
The check is part of the treatment: the intraocular pressure is measured, because it can rise temporarily after a capsulotomy, and we look at the eye once more. Exactly when we want to see you again we tell you at the appointment; it depends on the findings and on your pre-existing conditions. Whether new glasses make sense is decided only afterwards — visual acuity should stabilise first, and we would rather measure again than prescribe you lenses that will no longer be right in two weeks.
Risks — what we tell you beforehand
Even a short procedure without an incision has risks, and you should know them before you agree. They are the reason why a capsulotomy is not done as a precaution but when it solves a problem.
- A rise in intraocular pressure, usually temporary and within the first hours — hence the check after the procedure. Where someone is already being treated for glaucoma, the follow-up here is particularly attentive.
- Floating fragments of capsule in the field of vision, as described above.
- Irritation or inflammation inside the eye, which is treated with drops.
- Fine marks on the artificial lens, if the laser pulse grazes it.
- A displacement of the artificial lens — rare, and usually only later on. The opening in the capsule stays; it makes a later exchange of the artificial lens more demanding. That too is among the reasons why we do not laser as a precaution.
- Swelling at the point of sharpest vision(macular oedema), which can worsen vision again and is treated. Rare.
- A tear or a detachment of the retina. Rare, but the most serious possibility — and the reason why we tell you the warning signs of a retinal detachment in advance: flashes of light, a swarm of new black dots, a dark curtain from the side. These signs are not only for the first few days — get in touch about them whenever they appear.
Whether and how much these points weigh in your case depends on your eye: on the retina, on short-sightedness, on earlier inflammation and on how the operation went at the time. That is exactly what we discuss before the procedure — and if the outcome of that conversation is 'we wait a while longer', that is an outcome like any other.
Costs & health insurance
What does the insurer pay for — and what not?
Posterior capsule opacification is an illness in the insurance sense, and assessing and treating it are medical treatments. Where there is a medical indication this runs through basic health insurance (OKP); the deductible and co-payment apply as at any doctor's appointment. What is not included we tell you before the appointment.
| Service | Coverage | What this means for you |
|---|---|---|
Assessment for vision that has become hazy again | Basic insurance (OKP) | Visual acuity, examination at the slit lamp and assessment of the capsule behind the artificial lens — where there is a medical indication, a service of basic health insurance. That in the end it turns out to be 'only' posterior capsule opacification changes nothing about that. |
YAG capsulotomy (laser treatment of posterior capsule opacification) | Basic health insurance where indicated | The laser procedure is treatment of illness and is covered where there is a medical indication — that is, when the finding explains your symptoms, and not because the word appears in a report. It is equally indicated when the clouding blocks the view of the retina and a condition there could otherwise no longer be assessed or treated. |
Intraocular pressure check and follow-up check | Basic insurance (OKP) | Part of the treatment, not an additional service — it is the reason why a rise in pressure is noticed in time. |
New glasses or new lenses after the treatment | Self-pay service | Basic health insurance does not, as a rule, pay for the visual aid itself in adults; for children and for certain medical situations there are special provisions. Whether a new correction is worth having at all we measure only once your visual acuity has stabilised. |
Come to us with the haze, even if you are unsure whether it is 'bad enough' — and bring the operation report or the card for your artificial lens with you, if you have it to hand. With flashes of light and many new black dots, a shadow from the side, rapidly worsening vision or a red, painful, light-sensitive eye, on the other hand, the rule is: call today, not next week. Outside consulting hours the ophthalmic emergency service applies — contact it, or go directly to the emergency department of an eye hospital. A sudden, complete loss of vision in one eye — particularly together with headache, pain on chewing or difficulty with language and speech, and signs of paralysis — does not belong in the consultation but in an emergency department, immediately: call the ambulance (144).
Related topics
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Medically reviewed by PD Dr. med. Andrea von Rückmann
Frequently asked questions
- No. The clouded natural lens was removed during the operation, and the artificial lens that was implanted stays clear — it does not cloud over. What can cloud over is the thin capsule in which the artificial lens sits and which is deliberately left in place during the operation, because it holds the lens where it belongs. That is precisely posterior capsule opacification. For many people it feels like a relapse, because the symptoms are the same as before the operation, and yet it is something different: a clouding in front of the lens instead of in it. That is why the treatment is a different one too — not a second procedure in the operating theatre but a short laser procedure in the consulting room.
- Posterior capsule opacification is not an emergency. It develops over weeks to months, and nobody has to organise anything at short notice because of it. Treatment makes sense when the clouding troubles you in everyday life: reading, driving at dusk, working at the screen. If it hardly troubles you, waiting is an entirely defensible decision, and we say so too. There is one exception: if the clouding blocks the view of the retina, so that a condition there can no longer be assessed or treated, we advise treatment even when you yourself notice little. Something else applies, moreover, to symptoms that do not belong to posterior capsule opacification: flashes of light with many new black dots, a shadow moving in from the side, rapidly worsening vision or a red, painful, light-sensitive eye — even without nausea. With those you call the same day, outside consulting hours the ophthalmic emergency service or the emergency department of an eye hospital. And before that comes an emergency that does not belong in the consultation: a sudden, complete loss of vision in one eye — particularly together with headache, pain on chewing or difficulty with language and speech, and signs of paralysis — belongs in an emergency department immediately: call the ambulance (144).
- The procedure is regarded as painless. The eye is numbed beforehand with drops, and the laser works without touching it: no incision in the eye is needed, and nothing is introduced into the eye. What you perceive are short flashes of light and a soft clicking, sometimes a sensation of pressure from the contact lens with which the laser beam is focused on the capsule. No general anaesthetic is needed, and no preparation of the kind that precedes an operation either. You sit at a device that looks like the slit lamp you have already been examined at, with your chin and forehead on the rest.
- The laser procedure itself is short. Everything around it takes longer: before the procedure there is an examination and drops, and the drops need their time to work; afterwards comes the check. So please allow considerably more time for the appointment than for the laser — and plan the journey home so that you do not depend on driving yourself straight afterwards. How much time you should allow in your case we tell you when you book, once we know which eye and which finding it is.
- Plan on the basis that you cannot. If dilating drops are given for the procedure, near vision stays blurred for several hours and you are markedly more sensitive to glare — during that time you do not belong at the wheel. Take public transport, someone to accompany you or enough time on site, and bring sunglasses with you. Tell us when you book if you want to come by car; then we discuss beforehand what you have to reckon with.
- The opening the laser places in the capsule stays — it does not close over again. That is why treatment at this spot is as a rule a one-off, and repeated sessions are not the usual course. If vision later declines again, that is a reason to look again rather than to laser automatically a second time: there is more than one cause of a cloudier picture in the eye, and which one it is, is decided by the examination and not by the history.
- Yes. Assessing declining vision and the laser treatment of posterior capsule opacification are medical treatments and are billed through basic health insurance where there is a medical indication, as is the check afterwards. The deductible and co-payment apply as at any doctor's appointment. What does not run through basic health insurance is the visual aid itself: new glasses or new lenses that become worthwhile after the treatment are as a rule paid for by adults themselves; for children and for certain medical situations there are special provisions. What applies in your case we settle before the appointment — not on the bill.
A haze in front of your eye again? That should be looked at.
Whether it is posterior capsule opacification or something else is shown by the examination at the slit lamp. Tell us when you book when you were operated on and what has changed since — then we plan the appointment so that there is enough time.
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