Secondary Cataract (Posterior Capsule Opacification): Causes and YAG Laser Treatment

Months or years after a successful cataract operation, vision can slowly become hazy again, and many people fear that the cataract has returned. It has not. The usual cause is posterior capsule opacification (PCO), a clouding of the thin membrane behind the artificial lens. It is common, it does not damage the eye in adults, and a laser can clear it in a few minutes.

Can a cataract come back after surgery?

No. During cataract surgery the cloudy lens is removed, and UK patient guidance states plainly that cataracts cannot grow back. What remains is the capsule, the thin membrane that enclosed the lens; it is left in place on purpose to hold the new lens. Its back part, the posterior capsule, lies in the line of sight, so when it clouds the effect resembles a cataract — hence "secondary cataract", although it is not a true cataract.

Why does posterior capsule opacification happen?

Surgery cannot remove every microscopic lens cell lining the capsule. Over months and years, some of these cells multiply and spread across the back of the capsule, or the capsule wrinkles and thickens. The risk depends on:

• the lens design and material — lenses with a sharp, square edge and hydrophobic acrylic material act as a barrier to migrating cells, and NICE is updating its guidance to reflect this;
• age — lens cells are more active in younger people, and in young children clouding is almost universal;
• other conditions — diabetes and inflammation inside the eye (uveitis) are associated with more PCO; see complex cataract surgery.

How common is it?

Estimates vary with the lens used, the length of follow-up and the definition:

In the UK data, laser rates at 5 years ranged from 5.8% with a hydrophobic acrylic lens to 19.3% with a hydrophilic one.

What are the symptoms?

PCO develops gradually. Typical signs are vision that becomes hazy or blurred again after being clear, glare and halos from headlights or sunlight, and reduced contrast, so that faces, steps and print look washed out. People with trifocal and other multifocal lenses may notice it early, and capsule clouding is one of the treatable causes of dissatisfaction after premium lenses. But not every blur is PCO: dry eye, a small remaining prescription or swelling of the central retina can feel similar, so an examination comes first.

How is YAG laser capsulotomy done?

The treatment is Nd:YAG laser capsulotomy, an outpatient procedure in which no incision is made and no instrument enters the eye. It takes a few minutes.

1. Confirming the cause. Vision, eye pressure, the capsule and the retina are checked to make sure that PCO explains the symptoms.
2. Preparing the eye. Drops widen the pupil; a drop to prevent a pressure rise may be added, and a numbing drop is used if a contact lens is placed on the eye to focus the laser.
3. The laser. Sitting at the laser microscope, you keep your eye still while a series of tiny, precisely focused pulses opens a small round window in the center of the clouded capsule. It is usually not painful.
4. Afterwards. Eye pressure may be checked before you leave, and some people use drops for a few days. Vision usually clears within a day or so; a few floaters are common at first.

What are the risks?

YAG capsulotomy is quick and non-invasive but not free of risk. Recognized complications are a rise in eye pressure in the hours afterwards, swelling of the central retina (cystoid macular edema), small marks on the artificial lens (pitting) and, rarely, retinal detachment. See also risks and side effects.

Can posterior capsule opacification be prevented?

The risk can be reduced but not eliminated. Lens material and edge design have the clearest effect, together with careful removal of lens material during surgery. In children, sharp-edged lenses were associated with fewer laser treatments in one comparison (1 of 371 eyes versus 4 of 371). Keep a record of your lens model.

Treatment in Antalya or at home

YAG capsulotomy needs no overnight stay, so it fits easily into a visit — or it can be done by an ophthalmologist near your home if PCO appears after you return. Prof. Türkoğlu can examine the eye in Antalya, confirm whether the capsule is the cause of your symptoms and plan treatment; if you had surgery elsewhere, bring the operation summary. For the weeks after cataract surgery itself, see recovery and flying home.