What causes blindness after cataract surgery?

Cataract surgery is one of the most successful procedures in modern medicine. Most people experience a quick recovery and clear vision. But naturally, people worry about the risks—including the rare possibility of blindness.

Let’s be clear: permanent blindness after cataract surgery is extremely rare. But if you’re facing the decision to have cataract surgery, it’s important to understand what can go wrong—and what steps are taken to prevent it.

Infections (Endophthalmitis)

The most serious complication that can lead to blindness is a severe infection inside the eye called endophthalmitis. It’s very rare—occurring in about 1 in 10,000 to 1 in 20,000 cases—but it can cause permanent damage if not treated quickly.

What causes blindness after cataract surgery?
Bacteria can enter the eye during surgery or in the first few days after.

What are the signs?
Pain, redness, blurred vision, or increasing discomfort after surgery. If you have these symptoms, it’s vital to be seen urgently.

How is it prevented?
Every step in modern cataract surgery is designed to prevent infection. This includes using sterile equipment, antiseptic eye drops, and often antibiotic injections at the end of the procedure. Patients are also given antibiotic eye drops to use at home.

Retinal detachment

This is when the retina (the light-sensitive layer at the back of the eye) pulls away from the wall of the eye. It can cause permanent vision loss if not treated promptly.

How common is it?
Retinal detachment happens in about 1 in 1,000 cataract surgeries. The risk is slightly higher in people who are very short-sighted (high myopia).

What are the signs?
Flashes of light, a sudden shower of floaters, or a dark curtain coming across your vision.

How is it treated?
Retinal detachment is a surgical emergency. If treated early, vision can often be saved.

Swelling in the Retina (Cystoid Macular Oedema)

Some people develop swelling at the centre of the retina, known as cystoid macular oedema. It can cause blurry or distorted central vision after surgery.

Is it permanent?
Usually not. In most cases, it improves with anti-inflammatory drops or other treatment.

How is it prevented?
Patients at higher risk may be given anti-inflammatory medication around the time of surgery to reduce this risk.

Problems with the optic nerve

In people with glaucoma or certain types of eye disease, cataract surgery may sometimes worsen existing damage to the optic nerve. This is rare but can lead to permanent vision loss in extreme cases.

Other serious medical eye conditions

It’s important to remember that cataract surgery can’t fix every eye problem. If someone has an advanced eye disease—like late-stage macular degeneration or severe diabetic eye disease—they may not see well even after the cataract is removed. In some cases, these conditions may continue to worsen after surgery, even if the cataract surgery itself goes smoothly.

What can you do to reduce your risk?

• Choose an experienced surgeon. Like Professor Paul Ursell, who has performed thousands of successful cataract procedures.
• Follow pre-op and post-op instructions carefully. This includes using all prescribed drops and attending your follow-up appointments.
• Inform your surgeon of any medical conditions. Including diabetes, glaucoma, or a history of eye disease.
• Seek urgent help if something doesn’t feel right. You know your body best. If something feels off, don’t wait—get checked.

Blindness after cataract surgery is very rare. For most people, cataract surgery leads to a dramatic improvement in vision and quality of life. But like all medical procedures, there are risks. Knowing what they are—and choosing a surgeon who prioritises your safety—is the best way to protect your sight.

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