Can Cataracts Come Back After Surgery? Understanding Secondary Cataracts

A patient came to see me a few years after uncomplicated cataract surgery, convinced something had gone wrong. Her vision had been sharp for a long time, and over several months it had gradually dulled. Headlights had started to scatter again at night. She had reached the same conclusion most people in her position reach, which was that her cataract had come back.

It had not. Cataracts cannot come back. But the symptoms she described were real, they had a specific cause, and that cause has a well-established treatment that takes a few minutes and involves no incision.

The condition is called posterior capsule opacification, usually shortened to PCO. It is the most common long-term development after cataract surgery, and it is one of the more reassuring things I get to explain in clinic, because the fix is straightforward. It is also widely misunderstood, partly because of the unhelpful nickname it has acquired.

Why a cataract cannot return

To explain PCO I need to be precise about what cataract surgery actually removes.

Your natural lens sits inside a thin, transparent membrane called the lens capsule, which you can picture as a very fine elastic bag. When the lens becomes cloudy with age, we call it a cataract.

During surgery I make a small opening in the front of that capsule, break up the cloudy lens material with ultrasound, and remove it. The capsule itself stays in the eye. It has to, because it is what holds the artificial intraocular lens in the correct position for the rest of your life. So the back wall of the bag, the posterior capsule, remains behind the new lens as a clear membrane.

The natural lens is gone permanently. There is no biological mechanism by which it can regrow, and the artificial lens replacing it is made of acrylic or silicone, which does not cloud, yellow or degrade. This is the reason cataract surgery does not need repeating. I mentioned in 5 Things You Should Know About Cataracts that once the operation is done, it is done.

What can change is the capsule.

What posterior capsule opacification is

When I remove the lens material, a small population of lens epithelial cells inevitably remains along the inside of the capsule. These cells are microscopic and impossible to remove entirely. In most eyes they stay quiet. In some, they begin to divide, migrate across the back of the capsule and change character, and the previously clear membrane becomes hazy.

This happens in two broad patterns, and patients often have a mixture of both.

Fibrotic PCO occurs when the cells transform into fibroblast-like cells that lay down collagen. The capsule thickens, wrinkles and takes on a translucent, slightly crinkled appearance.

Pearl-type PCO occurs when the cells swell into rounded clusters, sometimes called Elschnig pearls, which cluster around the edge of the capsule and can drift into the visual axis. These tend to develop later and can occasionally appear quite suddenly.

Either way the effect is the same. A membrane that was clear is now scattering and absorbing light before it reaches your retina, sitting directly behind an artificial lens that is working perfectly well.

Why "secondary cataract" is a confusing name

You will see PCO described as a secondary cataract or an after-cataract. Both terms are in common use, including by clinicians, and both cause unnecessary alarm.

The names stuck because the symptoms genuinely resemble a cataract. Vision dulls gradually, glare increases, contrast fades. From the inside it feels like the same thing happening again.

But it is not the same tissue, it is not the same process, and it does not require the same treatment. A cataract requires an operation in a theatre. Posterior capsular opacity (PCO) is treated with a laser, in a chair, in an outpatient clinic. 

How common is it?

More common than most patients expect, and the figures depend heavily on how long you look.

The most useful dataset I know of comes from the Royal College of Ophthalmologists' National Ophthalmology Database in the United Kingdom, which analysed just over half a million cataract operations performed across 41 centres. In that cohort, PCO was recorded in 12.3 per cent of eyes overall, with observed rates rising steadily over time: 2.3 per cent at six months, 4.4 per cent at one year, 19.7 per cent at three years, 34.0 per cent at five years and 46.9 per cent at nine years.

An earlier meta-analysis of published studies produced broadly similar figures, with pooled estimates of around 12 per cent at one year, 21 per cent at three years and 28 per cent at five years.

So the commonly quoted range of 20 to 40 per cent is reasonable, provided it is anchored to a timeframe. Somewhere between one fifth and two fifths of patients develop visually significant PCO within three to five years of surgery. The longer you live after your cataract operation, the more likely you are to encounter it, which is one reason it is more relevant for patients having surgery in their sixties than in their late eighties.

None of this reflects poorly on the surgery. PCO is a biological response of the patient's own cells, not a technical failure. Modern lens designs with square edges and improved surgical technique have reduced the rates compared with the 1980s and 1990s, but nobody has eliminated it.

Who is more likely to develop PCO?

Several factors raise the likelihood:

• Younger age at surgery. Lens epithelial cells in younger eyes are more proliferative.

• Diabetes, particularly where there is diabetic retinopathy.

• Uveitis or any history of intraocular inflammation.

• High myopia and long eyes.

• Retinitis pigmentosa and some other retinal dystrophies.

• A complicated operation, for example where the capsule was compromised or the surgery was prolonged.

• Lens material and design. Hydrophobic acrylic lenses with a sharp posterior edge have generally been associated with lower rates than older designs, though the comparative literature is mixed over longer follow-up.

What it feels like

The symptoms usually build gradually over months, which is part of why patients often underestimate the change until it is well advanced.

• Vision that was crisp after surgery slowly becoming hazy or misty

• Glare and haloes around headlights and streetlights, often worse than before

• Reduced contrast, so low-contrast print and dimly lit environments become harder

• Colours appearing slightly washed out

• Occasionally, monocular double vision or ghosting, where a single image appears doubled in one eye

Timing varies widely. Most cases present between one and five years after surgery, though PCO can appear within months or not for a decade.

Two points worth emphasising. First, PCO is painless, and there is no redness or discharge. If your eye is painful, red or your vision has dropped suddenly, that is not PCO and it needs prompt assessment.

Second, not all clouding after cataract surgery is PCO. When a patient tells me their vision has deteriorated, I am also considering dry eye and ocular surface disease, which is common and often overlooked; a change in spectacle prescription; macular disease, including age-related macular degeneration and epiretinal membrane; corneal swelling; and progression of glaucoma. I have discussed some of these possibilities in Can Cataract Surgery Have Side Effects? An examination is what separates them, and treating the wrong thing helps nobody.

How PCO is diagnosed

The assessment is straightforward and involves no discomfort beyond dilating drops.

I measure your vision, check your intraocular pressure and examine the eye at the slit lamp. With the pupil dilated, the posterior capsule can be viewed directly, and shining light back through the eye makes any opacity show up clearly as a shadow against the illuminated retina.

The important judgement is not whether PCO is present. It is whether the PCO explains your symptoms. I have seen patients with visually obvious capsular haze who are entirely happy with their vision, and patients with minimal haze whose central capsule has clouded at exactly the wrong point and who are significantly troubled. Where the picture is unclear, retinal imaging helps rule out other causes before proceeding to treatment.

YAG laser capsulotomy

The treatment for symptomatic PCO is a laser procedure called an Nd:YAG posterior capsulotomy. You can read more about how it is performed in my practice on the laser capsulotomy page.

The laser delivers extremely short, focused pulses of energy to the clouded capsule behind the lens. Rather than burning tissue, each pulse creates a microscopic disruption at a precisely targeted point. A series of these pulses is used to create a small circular opening in the centre of the capsule, clearing the visual axis. The peripheral capsule is deliberately left intact, so the intraocular lens stays supported exactly where it is.

What happens on the day. You are given dilating drops and anaesthetic drops, so no injection or needle is involved. You sit at the laser, which resembles the examination microscope you have already encountered, and rest your chin and forehead against a support. I usually place a contact lens on the front of the eye with lubricating gel, which helps focus the laser accurately and keeps the eye steady. You will be asked to look at a fixation light and hold still. You will hear a series of clicks and may see brief flashes.

The laser itself typically takes a few minutes. Most patients find it uncomfortable rather than painful, and the main difficulty is usually holding still rather than any sensation from the laser. You go home the same day.

How effective is it? Reliably so. Published success rates for restoring vision are above 95 per cent. Where vision does not improve as expected, the usual explanation is a coexisting condition that was limiting vision independently, such as macular disease or optic nerve damage, which is why the assessment beforehand matters.

Improvement is often noticed within a day or two, though it can take a little longer to settle.

The risks

I take the view that all procedures deserve honest disclosure, however low the risk, and I wrote about this at greater length in How Safe Is Cataract Surgery? YAG capsulotomy is low-risk, but it is not risk-free, and describing it as trivial would not be accurate.

A rise in intraocular pressure is the most common event. Historically, without preventive treatment, a rise of 10 mmHg or more was reported in a substantial proportion of eyes. Pressure typically peaks three to four hours afterwards and settles within about a week. This matters particularly in patients who already have glaucoma, and as a glaucoma subspecialist I approach these cases with additional caution, often carefully checking the intraocular pressure shortly after the procedure.

Cystoid macular oedema, a swelling at the centre of the retina, occurs in a small percentage of eyes and can develop weeks to months later. It is treatable but can delay visual recovery.

Retinal detachment is the complication patients most often ask about. Reported rates following capsulotomy are very low (less than 1%), and it is worth knowing that whether the laser itself increases this risk, as opposed to the underlying features that make an eye prone to detachment in the first place, remains debated. At least one large study found no independent association. The risk is higher in long, short-sighted eyes, and in those patients I use the minimum energy and the smallest adequate opening.

Damage to the intraocular lens in the form of tiny pits can occur if the laser focus is not precisely behind the lens. Small pits do not usually affect vision measurably.

Floaters are common afterwards, caused by fragments of capsule dispersing into the vitreous gel. They typically become less noticeable over weeks.

Inflammation inside the eye is usually mild and settles with drops.

Because of this risk profile, I do not treat PCO simply because it is visible. I treat it when it is causing symptoms that matter to you. There is no advantage in performing a procedure early on an eye that is seeing well, and there is no penalty for waiting until the haze becomes bothersome. The decision belongs to you, and I would rather you made it without pressure. That approach is consistent with how I think about the timing of cataract surgery itself, which I discussed in How Long Is It Possible to Delay Cataract Surgery?

Afterwards

You can expect blurred vision for a few hours from the dilating drops, so arrange not to drive yourself home. Anti-inflammatory drops are often prescribed for a short period, and I usually check the pressure before you leave and review you within a few weeks.

Contact the practice promptly if you notice increasing pain, a significant drop in vision, a sudden shower of new floaters, or flashing lights or a shadow moving across your field of view. The last of these can indicate a retinal problem and should be assessed the same day.

Can PCO come back after laser treatment?

In adults, rarely. Once a clear opening has been made in the capsule, it generally stays open, because there is no tissue left in the centre to grow across. Recurrence is well documented in children, whose cells are far more proliferative, but it is uncommon in adult eyes. Most patients need the procedure once per eye and never think about it again.

Cost and access in Australia

Nd:YAG capsulotomy is a Medicare-rebated procedure when it is clinically indicated. It is performed in an outpatient setting rather than an operating theatre, so hospital and anaesthetic costs do not generally apply. Depending on your ophthalmologist's fee arrangements, a gap payment may apply. As with any procedure, ask for a written estimate beforehand.

Frequently asked questions

Is PCO a sign that my cataract surgery was done badly?
No. It is a response of your own remaining lens cells and it occurs in the hands of every cataract surgeon. Rates are influenced by lens design and technique, but no method eliminates it.

Do both eyes need treating?
Only if both are symptomatic. PCO often develops in both eyes but not necessarily at the same rate or the same time.

Will I need my glasses prescription changed afterwards?
Possibly. Clearing the capsule generally does not alter your refraction, but it may be worth updating your spectacles several weeks following the procedure if the vision remains blurry.

Can PCO be prevented?
Not reliably. Lens design, careful removal of lens material and thorough polishing of the capsule during surgery all help, and rates have fallen over the past few decades. There is no drop or supplement that prevents it.

How long does the appointment take?
The laser itself is usually a few minutes. Allow a couple of hours for the visit overall, to account for dilating drops, examination and a pressure check afterwards.

Should I have the laser done straight away if PCO is found?
Not necessarily. If your vision is comfortable, there is no benefit in treating it early. The right time is when the haze is interfering with things you want to do.

In summary

Your cataract will not come back. If your vision clouds again months or years after surgery, the likely explanation is posterior capsule opacification, a haze in the membrane that supports your lens implant. It affects a meaningful minority of patients over the years following surgery, it is painless, and it is treated with a brief laser procedure that carries a low but real set of risks and a high success rate.

The most useful thing you can do is have it looked at rather than assume it. Gradual clouding has several possible causes, and only an examination will tell you which one you are dealing with.

For general information about cataracts and cataract surgery in Australia, healthdirect is a reliable starting point. The Royal College of Ophthalmologists' National Ophthalmology Database study on posterior capsule opacification is the source of the incidence figures cited above, for readers who would like to see the underlying data.

Further answers to common questions can be found on my FAQs page, and I have written more about how cataracts affect daily life in Clouded Living.

A/Prof Simon Skalicky is a specialist ophthalmologist (FRANZCO) with subspecialty training in glaucoma and cataract surgery, and an Associate Professor at the University of Melbourne.

This article provides general information only and is not a substitute for individual medical advice. Outcomes vary between patients, and all procedures carry risks. Whether YAG laser capsulotomy is appropriate for you can only be determined through a personal consultation and examination. Please discuss your circumstances, including the benefits, risks and costs, with a qualified ophthalmologist.

References

1. Ursell PG, Dhariwal M, O'Boyle D, Khan J, Venerus A. 5 year incidence of PCO and Nd:YAG capsulotomy. Royal College of Ophthalmologists' National Ophthalmology Database study of cataract surgery: Report 9, risk factors for posterior capsule opacification. Eye 2023.

2. Schaumberg DA, Dana MR, Christen WG, Glynn RJ. A systematic overview of the incidence of posterior capsule opacification. Ophthalmology 1998;105:1213–21.

3. American Academy of Ophthalmology. Nd:YAG Laser Posterior Capsulotomy — complications and management.

4. Elbaz U, et al. Nd:YAG capsulotomy is not a risk factor for retinal detachment after phacoemulsification cataract surgery. Acta Ophthalmologica 2021.

5. Effect of Nd:YAG laser posterior capsulotomy on intraocular pressure, refraction and macular thickness. Clinical Ophthalmology 2019.

6. healthdirect Australia. Cataract surgery.