Capsule Opacification

What is capsule opacification?

Capsule opacification, often referred to as posterior capsule opacification (PCO), is a common change that can occur after cataract surgery. During cataract surgery, the eye’s cloudy natural lens is removed and replaced with a clear, artificial intraocular lens (IOL). The thin, transparent membrane (capsule) that held the original lens is left in place to support the implant.

In some people, lens cells left behind after surgery can grow and spread over the back part of the capsule, making it cloudy or wrinkled. This gradual change can scatter light and reduce the sharpness of vision.

Is capsule opacification common?

Yes. Capsule opacification is the most frequent long-term change following cataract surgery, affecting up to 20–50% of patients within a few years. It can develop months or even years after the operation. It’s not considered a complication in the sense of a surgical error, as it’s part of the natural healing response in some eyes.

Symptoms of capsule opacification

When the capsule becomes cloudy, you may notice:

• Blurred or hazy vision
• Glare or halos, particularly around lights at night
• Faded or less vibrant colours
• Difficulty reading or recognising faces, especially in low light

Because these symptoms are similar to the original cataract, PCO is sometimes called a ‘secondary cataract’, though it’s not actually a cataract returning.

Posterior capsule opacification grading

PCO can be graded based on its appearance and how much it affects vision:

• Mild PCO: Slight haziness, often detected during routine examination but with minimal impact on vision.
• Moderate PCO: Noticeable clouding affecting reading vision and contrast, particularly in low light.
• Severe PCO: Significant loss of clarity, glare, and reduced visual function in daily activities.

Grading is usually done by an ophthalmologist using slit-lamp examination or imaging systems such as retroillumination photography.

Causes of capsule opacification

PCO occurs when lens epithelial cells left in the capsule after cataract surgery begin to grow and cluster on the capsule surface. This can happen more often in:

• Younger patients (under 60)
• People with certain eye conditions, such as uveitis or high myopia
• Patients whose lens capsule experienced more manipulation during surgery
• Certain types of IOL material or design (modern lenses reduce the risk)

How to prevent posterior capsule opacification

While PCO cannot always be prevented, certain surgical techniques and lens choices can reduce the risk:

• Using a square-edged IOL design that creates a barrier to cell migration
• Meticulous surgical cleaning (polishing) of lens epithelial cells during cataract removal
• Maintaining an intact, stable capsule during surgery
• Using lens materials shown to have lower rates of PCO formation (e.g. hydrophobic acrylic)

Your surgeon will select the most suitable approach for your eyes to minimise the chance of PCO developing.

How capsule opacification is treated

Treatment is straightforward and performed as an outpatient procedure called YAG laser capsulotomy. The laser creates a small, clear opening in the centre of the capsule, restoring a clear visual pathway.

• Painless: The procedure is quick and requires only numbing drops
• Fast recovery: Most people notice clearer vision within hours to days
• Long-term result: Once the cloudy capsule is removed, PCO does not usually return