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Why Can Vision Become Cloudy Again After Cataract Surgery?

Cloudy vision after cataract surgery is usually posterior capsule opacification, a common clouding behind the implant treated with a quick YAG laser procedure.

By Vireon Medical Editorial TeamFirst published Evidence checked through

Short answer

Usually because of posterior capsule opacification (PCO), sometimes called a “secondary cataract”: the thin membrane that holds the lens implant gradually thickens and mists over. The cataract itself cannot come back, and PCO is the most common long-term complication of cataract surgery. It can appear months or years later and is usually treated with a quick outpatient laser procedure called YAG laser capsulotomy. Not every case of cloudy vision after surgery is PCO, though, so a proper eye examination is needed to find the cause.

Key points

  • PCO is clouding of the lens capsule behind the implant, not a returning cataract.
  • It is the most common long-term complication of cataract surgery.
  • It can develop months or years after the operation.
  • YAG laser capsulotomy takes about 5 to 10 minutes and is not usually painful.
  • Lens implants with sharp-edged optics are linked to less PCO.

What posterior capsule opacification is

During cataract surgery, the cloudy natural lens is removed and a clear artificial lens is placed inside the lens capsule, a thin, bag-like membrane that is left in place to hold it1. Over time, the back (posterior) part of this capsule can thicken and mist over, blurring vision3.

A Cochrane review describes PCO as the most common long-term complication of cataract surgery4, and the Royal College of Ophthalmologists calls it the commonest reason for vision getting worse after lens replacement surgery, appearing months or years afterwards2. The NHS lists it among the possible complications of cataract surgery1.

How it differs from the original cataract

FeatureOriginal cataractPosterior capsule opacification
What is cloudyThe eye’s natural lens1The capsule behind the artificial lens3
When it occursBefore surgeryMonths or years after surgery12
Usual treatmentSurgery to replace the lens1YAG laser capsulotomy, without an incision23
PCO is sometimes called a “secondary cataract”, but the natural lens has already been removed.

How it is treated

PCO is usually treated with YAG laser capsulotomy, in which a laser makes a small opening in the clouded capsule so light can pass clearly again24. An NHS hospital leaflet describes the process3:

  • Drops widen the pupil, taking about 10 to 15 minutes to work.
  • You sit at a laser machine similar to the microscope used in eye clinics; a contact lens may be placed on the numbed eye.
  • The treatment takes 5 to 10 minutes and is not described as painful; you may hear clicks and see bright lights.
  • Vision may be dazzled for several hours, so you should not drive until it clears.
  • Floaters are common for a few days and should settle.

It is a very common procedure: a French national study estimated around 312,000 capsulotomies in France in 2017, with an average patient age of about 755.

Risks of laser treatment

The same leaflet lists raised eye pressure, which can be treated with drops or tablets; fluid build-up in the retina, which can reduce vision; and, rarely, a retinal tear or detachment in the 3 months after treatment3. The Cochrane review notes that capsulotomy carries its own risks and is not widely available in every country, which is one reason for interest in preventing PCO in the first place4.

Can it be prevented?

Partly. A Cochrane review of 66 randomised trials found that lens implants with sharp-edged optics had significantly lower PCO scores and laser treatment rates than round-edged ones, and concluded that sharp-edged lenses should be preferred. There was no clear difference between lens materials, and the choice of anti-inflammatory drops after surgery did not appear to affect PCO4. The advantage of sharp-edged lenses is well supported by trials: Strong.

Other causes of blurred vision after cataract surgery

PCO is common, but it is not the only explanation. A changed glasses prescription, retinal swelling, retinal detachment, inflammation or the lens implant shifting can all affect vision16, and cataract surgery cannot restore sight lost to conditions such as macular degeneration, glaucoma or diabetic eye disease6. This is why gradual clouding should be examined rather than assumed to be PCO.

When to seek medical advice

Gradually cloudy or blurry vision after cataract surgery warrants a visit to an optician. Seek urgent help (in the UK, call 111) for sudden new floaters, flashes of light, a dark curtain or shadow across your vision, or sudden blurring, which may signal a detached retina1. After laser capsulotomy, contact the eye unit about flashing lights, reduced vision, pain or redness3.

Common questions

Can a cataract grow back?

No; the natural lens has been removed, but the capsule behind the implant can cloud over months or years later12.

Does YAG laser treatment hurt?

It is not usually painful; numbing drops are used and the treatment takes about 5 to 10 minutes3.

Can I drive home after YAG laser?

No; vision can be dazzled for several hours, so you should not drive until it clears3.

Does the type of lens implant matter?

Yes, the edge design matters more than the material: sharp-edged optics are linked to less PCO4.

Bottom line

Cloudy vision returning after cataract surgery is most often due to posterior capsule opacification, a common and treatable clouding of the membrane behind the implant. A brief laser treatment usually clears it, but other causes need to be ruled out, and sudden changes need urgent attention.

Sources

  1. NHS. Cataract surgery. NHS website; reviewed 2025. https://www.nhs.uk/tests-and-treatments/cataract-surgery/. Accessed 5 November 2026.
  2. The Royal College of Ophthalmologists. Refractive lens exchange: patient information. RCOphth; 2024. https://rcophth.ac.uk/wp-content/uploads/2020/05/Refractive-Lens-Exchange-Patient-Information-1.pdf. Accessed 5 November 2026.
  3. Gloucestershire Hospitals NHS Foundation Trust. Yag laser capsulotomy (GHPI0354). Gloucestershire Hospitals; 2024. https://www.gloshospitals.nhs.uk/your-visit/patient-information-leaflets/yag-laser-capsulotomy-ghpi0354/. Accessed 5 November 2026.
  4. Findl O, Buehl W, Bauer P, Sycha T. Interventions for preventing posterior capsule opacification. Cochrane Database of Systematic Reviews; 2010;(2):CD003738. https://doi.org/10.1002/14651858.CD003738.pub3.
  5. Incidence of Nd:YAG laser capsulotomy following cataract surgery: a population-based nation-wide study (FreYAG1 study). BMC Ophthalmology; 2023. https://doaj.org/article/101decfbc43d4ceab38c5c4098e96026. Accessed 5 November 2026.
  6. American Academy of Ophthalmology. Cataract surgery: risks, recovery, costs. AAO EyeSmart; 2026. https://www.aao.org/eye-health/diseases/what-is-cataract-surgery. Accessed 5 November 2026.

Article history

  • — First published.