Cataract surgery: both eyes on the same day or on different days?

People who need cataract surgery on both eyes may wonder whether it is better to have them done on the same day or on different days. In this blog, Sarah Chapman looks at the Cochrane evidence on how the two approaches compare and discusses what else might be important to consider.

There is a shorter version of this blog – Cataract surgery: a quick look. Both blogs have links to useful information for patients. Stay on this page if you would like a bit more detail and discussion.

Take-home points It is very common for people to develop cataracts, often in both eyes, as they age. These can be treated by surgery to remove the cataract and replace the cloudy lens of the eye with a clear plastic one. A Cochrane Review comparing the safety and effectiveness of operating on both eyes on the same day or on different days suggests “there are probably no clinically important differences in outcomes” between the two approaches. Same day surgery, which saves time and resources, is becoming more common in the UK. NICE guidelines recommend considering it for people at low risk of eye complications. Personal preferences and priorities are important when making treatment choices. These might include your feelings about more/fewer hospital visits and one operation versus two, as well as considerations around recovery from surgery and disruption to your usual activities.

Cataract surgery seems to me a remarkable thing. In under an hour, it’s out with the old lens, in with the new, and off you go. All being well, you’ll soon be enjoying good vision – perhaps the best it’s been for a very long time. At least, those of us with access to this surgery will…*

Here in the UK, cataract surgery is available on the NHS, though some people pay to have it done privately. I know lots of people who have either had cataracts removed or are on a waiting list for surgery, and this is unsurprising. Many of us develop them as we age, often in both eyes, with factors such as eye injury, diabetes, smoking or too much alcohol, or a family history of cataracts increasing the risk.

What is a cataract?

A cataract is a clouding of the lens of the eye, affecting the vision. It gets worse over time and, if a change to your glasses prescription is no longer enough, then surgery is needed to replace the cloudy lens (the cataract) with a clear plastic one.

You may have heard that the cataract has to become ‘ripe’ or ‘ready’ before it’s removed, but this is no longer true. Technology and techniques have moved on and the surgery is now possible at any stage. Your optician can tell you whether your cataract meets the criteria for removal on the NHS.

It’s usual for cataract surgery to be done under local anaesthetic, so you’ll be awake but won’t feel pain in your eye or the area around it. The cataract is taken out and the new lens put in through a tiny cut. You can read patient-friendly information from the links below, which give clear explanations about cataracts, the operation and what to expect, as well as practical information.

Timing of surgery – two cataracts at once?

When my sister was preparing to have her cataracts removed, I was surprised to hear that she was to have both done on the same day. Soon after, my uncle had his done with some weeks between the first and second eye being operated on, which is the more common approach in the UK. I wondered what the evidence is for how the two approaches compare, and what else might be important to consider.

A recent Cochrane Review, Immediate sequential bilateral surgery versus delayed sequential bilateral surgery for cataracts (April 2022) has brought together evidence that might answer questions about whether operating on both eyes on the same day (Immediate sequential bilateral surgery or ISBS) is as safe and effective as doing them on different days (delayed sequential bilateral surgery or DSBS). The evidence is relevant to people with age-related cataracts.

The bottom line:

“…there are probably no clinically important differences in outcomes” between doing cataract surgery on one eye and then the other on the same day compared with doing them on different days.

A bit more detail:

  • There was little evidence on the risk of infection which is, thankfully, a very rare complication. The review authors say there was a very low risk in both groups. Based on very few cases of infection in one eye, it seems that the timing of surgery (doing two eyes on the same day or on different days) may make little to no difference, but we can’t be sure.
  • There may be little to no difference in other complications, such as bleeding or retinal detachment, either during or after the operation (but again the evidence is very uncertain).
  • There is probably little to no difference between the two in visual outcomes, one to three months after surgery.
  • There was probably little to no difference between the two in the answers people gave in questionnaires after surgery. The questionnaires asked about visual function and patient satisfaction with vision.

Same-day surgery saves time and money

The Cochrane Review can’t tell us about this but, in terms of resources and convenience, one visit has distinct advantages over two. The pandemic gave same-day surgery a boost, with surgeons being encouraged to offer it to those suitable for it, given the advantages of reducing hospital visits and using services more efficiently (Healey, 2021).

For patients, same-day surgery means fewer hospital visits and only one post-operative recovery period – so less time off work or away from other activities and less time needing help at home after surgery. For people with cataracts in both eyes, they stand to gain more from having them done together, as their vision after surgery will be better than during a period of waiting for the second cataract to be removed. This also avoids the increased risk of falls that is associated with the period between a first and second cataract operation. For the few people who need to have a general anaesthetic (such as some people with learning difficulties or dementia), a single operation exposes them to the associated risks once rather than twice.

However, in the NHS, it seems that the way payment works is a disincentive to give patients the option of having both eyes operated on together. According to Consultant Ophthalmic Surgeon Professor David Spalton at St Thomas’s Hospital in London, speaking in 2021, “If you do two operations, you get paid for two operations. If you do it as bilateral, you usually get paid about one and a half.” (Healey, 2021).

Is same-day cataract surgery more risky?

Surgeons are divided about the balance of risks and benefits for same-day surgery. Some say the risk of infection in both eyes is unacceptable. But the chances of this rare complication are reduced by measures such as using antibiotics during surgery and treating each eye as if they belong to two different people – for example, using fresh equipment and different batches of fluids for each.

Although delaying the second operation enables the surgeon to check the results of the first before doing the second eye, doing one and then immediately the other means the surgeon has information from how the first eye behaved during surgery that may be helpful as they do the second.

In the UK, the NICE guideline Cataracts in adults: management (October 2017) says same-day surgery for both eyes should be considered for people who are at low risk of eye complications, and for some people who need to have surgery done under general anaesthetic.

In the Netherlands, where current guidelines do not allow same-day surgery on both eyes, a multi-centre randomised controlled trial is in progress to compare the two approaches (O’hEineachain, 2021). Preliminary results show “comparable safety and effectiveness” for same-day versus delayed second eye surgery. Let’s hope that when the Cochrane Review is updated, this and other studies will be available to add to the evidence.

What’s important to you?

 There are three key elements to making choices about any health treatments:

  • what your preferences and priorities are
  • clinical expertise
  • information from the best available evidence, including an awareness of where there are uncertainties about the effects of treatment

This can be a useful basis for discussing options with a healthcare professional involved in your care.

You can ask your ophthalmologist (eye specialist) whether having both cataracts operated on at the same appointment is an option for you. They will discuss any considerations, including the risks and how these apply to you.

If you are given the choice between having two eyes done on the same day or at different appointments, given that the available evidence shows there is probably little to no difference in visual outcomes and safety, then other considerations may be deciding factors. These may include your feelings about having one operation and recovery period versus two, the resources available to you (such as help at home while you recover) and the impact on your usual activities, such as driving, work, or care responsibilities.

Find out more

*As with so much else, enormous regional inequalities exist. More than 90% of people with visual impairment due to cataracts live in low- and middle-income countries, where access to this relatively simple and cost-effective treatment is often restricted.

Join in the conversation on Twitter with @CochraneUK @SarahChapman30 or leave a comment on the blog.

Please note, we cannot give specific medical advice and do not publish comments that link to individual pages requesting donations or to commercial sites, or appear to endorse commercial products. We welcome diverse views and encourage discussion but we ask that comments are respectful and reserve the right to not publish any we consider offensive. Cochrane UK does not fact check – or endorse – readers’ comments, including any treatments mentioned.

References (pdf)

Sarah Chapman has nothing to disclose.



Cataract surgery: both eyes on the same day or on different days? by Sarah Chapman

is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International

6 Comments on this post

  1. My dad had two separate surgery appointments scheduled for cataract and was stressed about overall ‘down time’ and arranging all the travel to appointments and follow ups. I shared the Cochrane Review and this blog post with him. Knowing that there were no clinical outcome differences and he was low risk for complications, he shared then shared the review with his doctor and his preferences and discussed changing his appointments. He was rebooked for both eyes in one visit last week and has had a fast, one-time recovery! Many thanks for helping inform the decision making process with evidence!

    Muriah Umoquit / Reply
    • Thanks so much for sharing this with us, Muriah. We’re so pleased to read about your dad’s positive experience – and how he was able to use the review, and this blog, to help make the best decision for him!

      Selena Ryan-Vig / (in reply to Muriah Umoquit) Reply
  2. My cataract operations were carried out in a private eye hospital but as a NHS patient; at the pre-op consultation my request to have both done at the same time was refused. The hospital administration was most efficient, the staff very competent and the operations on my eyes, twelve weeks apart, successful. The establishment gives the impression of being very successful financially and appears to be one of three such private eye hospitals in the Southampton area. If the clinical evidence as to separate or simultaneous operations is as scant as is suggested above and the payment for performing operations is in the manner quoted at St. Thomas’ then clearly the decision about the pattern of operations is a question of cash-flow and not clinical necessity.

    Roger Hardy / Reply
  3. This is very clear and thorough. Having had two cataracts replaced at two different locations. I have to say, that, in hindsight if I’d been given the opportunity, I would have been happy to have had tgem replaced on the same day….. But because the 2nd location was much more efficient than my local hospital. I was referred to the 2nd location BY the NHS, but the treatment seemed more like private treatment. Having 2 cataracts replaced on the same occasion would have been brilliant, because my sight immediately became so much better.

    Viv Lever / Reply
    • Thank you for taking the time to comment; I’m glad you found this blog clear and thorough. It’s great that you have had a good result from your operations. Hopefully, it will become much more common to offer people the choice to have two done at once.
      Best wishes,
      Sarah Chapman

      Sarah Chapman / (in reply to Viv Lever) Reply
    • I wondered about that. I am going to see a Dr in about 5 hours who does cataract surgeries. Can I get both done in the same day if I live alone? Do Dr automatically 2 different set of instruments for the surgery. My Dr once worked in East London and South Africa. Now he works in Canada.

      Monique Ashby / (in reply to Viv Lever) Reply

Leave a Reply

Your email address will not be published.

*