Cataract Surgery Risks and Complications: How Likely, How Serious
By Pauline Driscoll | Medically reviewed by Mr Lewis Pereira, FRCOphth
Published April 13, 2026 · Last reviewed April 16, 2026 · 3 min read
Key takeaways
- Cataract surgery is one of the most common and successful operations, and serious sight-threatening complications are uncommon, often quoted as roughly 1 in 1,000.
- Infection inside the eye (endophthalmitis) is rare but serious, which is why antibiotic drops and sterile technique are used.
- Cystoid macular oedema, swelling of the retina, is a common cause of blurred vision after surgery and usually settles with treatment.
- Posterior capsule rupture and a dropped lens fragment can happen during surgery and may need further treatment, but a good result is still usual.
- Retinal detachment is rare and higher in very short-sighted eyes; refractive surprise means the focus is not quite on target and can be corrected with glasses.
Cataract surgery is one of the most common and most successful operations performed, and serious sight-threatening complications are uncommon, with the risk of a complication that threatens sight often quoted as roughly 1 in 1,000, about 0.1%, varying with the eye and any other conditions1. Around 9 in 10 people achieve improved vision assuming no other eye disease, so the risks are real but small and worth weighing against how much the cataract limits daily life2.
This is an honest deep-dive into what can go wrong, checked by a consultant ophthalmic surgeon. For the operation in full, see cataract surgery, and for what healing normally looks like, cataract surgery recovery.
How likely a serious complication is
A serious, sight-threatening complication is uncommon, with the risk often quoted as roughly 1 in 1,0001. Most complications that do occur are treatable and do not cost you your sight, and the great majority of operations go entirely to plan.
I will be honest: the risk numbers were what kept me awake before my first eye. What helped was understanding that roughly 1 in 1,000 is the figure for a serious sight-threatening problem, not for any hiccup at all, and that even when something less serious happens it is usually managed3. Reading the named risks plainly, rather than imagining a vague catastrophe, made the decision easier rather than harder.
Infection and retinal swelling
Infection inside the eye (endophthalmitis) is rare but serious, which is why antibiotic drops and sterile technique are used1. The warning signs are increasing pain, redness, worsening vision and discharge in the days after surgery, and they need urgent assessment.
Cystoid macular oedema, swelling at the centre of the retina, is a common cause of blurred vision after surgery and usually settles with treatment, typically anti-inflammatory drops2. It is one reason your vision may dip a little weeks after an apparently smooth operation, and it is generally temporary.
Capsule rupture, dropped fragments and retinal detachment
During surgery the cloudy lens is removed from a thin capsule that is left in place to hold the new lens. Occasionally that capsule tears, a posterior capsule rupture, and a fragment of lens can drop into the back of the eye, which may need further treatment, though a good final result is still usual3.
Retinal detachment is rare and higher in very short-sighted eyes, where the retina lifts away from the back of the eye2. Sudden new floaters, flashing lights or a shadow across the vision are warning signs that need urgent attention, because prompt treatment gives a far better outcome.
Refractive surprise and managing expectations
A refractive surprise means the result is not quite on target, so you may be more long or short-sighted than expected, usually correctable with glasses or sometimes a further procedure1. Careful measurements before surgery reduce the chance, but the eye does not always heal exactly to prediction.
The decision to operate is shared with your surgeon, weighing how much the cataract limits you against these uncommon risks, and an eye with other conditions may have a good operation but limited final vision because of the other problem4. That honesty about expectations is what made me trust the advice I was given. For the most common later issue, the capsule clouding over, see posterior capsule opacification, and for the calm, plain version of this whole question, can cataract surgery go wrong.
References
- Cataract surgery, NHS. ↩
- Cataract surgery, American Academy of Ophthalmology. ↩
- Understanding cataracts and cataract surgery, Royal College of Ophthalmologists. ↩
- Cataracts in adults: management (NG77), NICE. ↩
Common questions
How risky is cataract surgery?
Cataract surgery is one of the most common and most successful operations performed, and serious complications are uncommon. The risk of a serious complication that threatens sight is often quoted as roughly 1 in 1,000, about 0.1%, varying with the eye and any other conditions. Most people, around 9 in 10 assuming no other eye disease, achieve improved vision. The risks are real but small and worth weighing against how much the cataract limits daily life.
What is the most common complication of cataract surgery?
Posterior capsule opacification, sometimes called secondary cataract, is the most common later issue, where the capsule behind the new lens clouds over months to years. It is not the cataract coming back, and it is fixed in minutes with a painless YAG laser treatment in clinic. During surgery, cystoid macular oedema, swelling at the centre of the retina, is a common cause of blurred vision and usually settles with drops.
Can you get an infection after cataract surgery?
Infection inside the eye, called endophthalmitis, is a rare but serious complication. It is why antibiotic drops and strict sterile technique are used, and why you finish the full course of drops. Warning signs are increasing pain, redness, worsening vision and discharge in the days after surgery. If these occur, contact your eye team urgently, because early treatment matters.
What is a posterior capsule rupture?
During surgery the cloudy lens is removed from a thin capsule that is left in place to hold the new lens. Occasionally this capsule tears, called a posterior capsule rupture, and a fragment of lens can drop into the back of the eye. The surgeon manages this during or after the operation, sometimes with a further procedure, and most eyes still achieve a good final result.
Can cataract surgery cause retinal detachment?
Retinal detachment is a rare complication of cataract surgery, where the retina lifts away from the back of the eye. The risk is higher in people who are very short-sighted. Sudden new floaters, flashing lights or a shadow or curtain across the vision are warning signs and need urgent assessment, because a detachment treated promptly has a far better outcome.
What is a refractive surprise after cataract surgery?
A refractive surprise means the final focus of the eye is not quite on the target the surgeon aimed for, so you may be more long or short-sighted than expected. It is usually correctable with glasses or, in some cases, a further procedure. Careful measurements before surgery reduce the chance, but the eye does not always heal exactly to prediction.
Should the risks put me off cataract surgery?
For most people the small risks are outweighed by the benefit, given how common and successful the operation is. The decision is shared with your surgeon and weighs how much the cataract limits your daily life against the uncommon risks. If you have another eye condition, the balance and the likely final vision are discussed honestly at your assessment so you can decide with realistic expectations.
Written by Pauline Driscoll. Medically reviewed by Mr Lewis Pereira, FRCOphth.
Our guides are written from personal experience and reviewed by a qualified clinician for accuracy. Read our editorial policy.
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