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When a patient has to undergo cataract surgery in both eyes, one of the most frequent questions the ophthalmologist hears concerns the possibility of operating on both eyes on the same day by means of the so-called immediate bilateral cataract.

In many countries and for most patients, the approach whereby one eye is operated on at a time is still preferred, with the non-dominant eye being operated on first to allow visual function to stabilise and to manage any postoperative complications.

The 2025 data presented at the ESCRS (European Society of Cataract and Refractive Surgeons) congress in Copenhagen seem, however, to challenge this trend and suggest that immediate bilateral cataract surgery can offer excellent visual results and faster recovery for patients.

In this review, we aim to explore the advantages and indications of simultaneous bilateral intervention, as opposed to two interventions deferred in time.

Deferred surgery: what advantages

According to the most widespread conventional approach, when both eyes have to be operated on for cataracts, the so-called 'staged surgery' is favoured, whereby the two surgical procedures are spaced a few days to several weeks apart, in order to realise a number of advantages, which we will go into in more detail.

1. Allowing the first eye to stabilise

Cataract surgery on only one eye allows visual function to stabilise. The first improvements in the operated eye begin to be perceived within 48-72 hours, but slight progress continues to occur for weeks. This time window allows residual inflammation to disappear, stabilises the eye tissues and gives the brain time to adapt to the new intraocular lens, implanted in place of the natural lens.

This recovery time can be especially important if the eyes are predisposed to dry eye or are easily susceptible to redness and inflammation.

It can also be important to have an 'emotional' recovery time, as patients sometimes feel a little disoriented after cataracts. Consider that after removal of the opacified cataract the patient sees much sharper, with brilliant colours and much sharper contrasts.

In addition, at normal post-operative check-ups, the surgeon can measure outcomes in terms of recovered visual acuity and assess any adjustments. In the case of abnormalities, such as swelling, discomfort or visual aberrations, a fine-tuning can be scheduled for the second operation.

2. Reducing the risk of complications

The most frequently used argument in support of 'staged cataract surgery' is the lower risk of serious complications. Although cataract surgery procedures today are extremely safe, there is always a limited risk of infection, inflammation or surgical error. Endophthalmitis, for example, is fortunately an increasingly rare occurrence that could occur and have a dramatic impact on visual function and, in the most unfortunate cases, lead to blindness.

By spacing out operations on the two eyes, even by only a couple of weeks, a 'safety net' is introduced, because if a complication arises in the eye that was operated on first, the second eye remains healthy and intact until the problem is overcome. This caution may be important especially when patients have systemic diseases, such as diabetes, or specific ocular conditions, which may favour the onset of postoperative complications.

3. Monitoring and correcting side effects

Each of the two eyes has unique characteristics, even in the same individual. While the two cataracts may appear similar, the shape of the eyeball, specific refractive errors, and subtle anatomical differences can affect how each eye responds to surgery.

By separating the two surgeries, it is possible to monitor how the first eye responds: whether more inflammation than expected occurs, whether there is slower visual recovery or sensitisation to some eye drops occurs. These eventualities will have to be properly assessed when the surgery on the second eye is performed.

In addition, delayed surgery offers additional time to confirm, refine or completely change the choice of IOL to be implanted in the second eye, especially when using devices such as EDOF IOLs or toric IOLs, which have the ultimate goal of emancipating from the use of spectacles.

In addition, some refractive adjustments can be made through 'real-time optimisation' in relation to the fact that one eye may perform better in distance vision and the other in near vision.

Bilateral surgery: advantages and indications

Bilateral cataract is an approach that began to spread in clinical practice during the COVID-19 pandemic, when efforts were made to optimise the number of hospital admissions.

In 2025 at the 43rd ESCRS Congress, the results of a study, conducted by Vincenzo Maurino and Gabriele Gallo Afflitto of Moorfields Eye Hospital in London, were presented, according to which the immediate bilateral cataract surgeryi.e. the surgical option of operating on both eyes in the same operating session, appears to be a safe and advantageous alternative.

The study compared the results of patients with different types of intraocular lens implantation with both immediate bilateral surgery (ISBCS) and delayed bilateral surgery (DSBCS) and the final refractive outcome was very similar between the groups.

Let us examine in detail the advantages of immediate bilateral surgery.

1. Less time and fewer appointments

One of the main reasons why the bilateral approach is favoured by patients is that they have to undergo only one set of pre-operative examinations, face only one trip to the operating site, and only one round of post-operative check-ups. These advantages have particular appeal for those who have to travel great distances, rely on a few companions, or simply want to get everything done as soon as possible.

Among other things, a single operating session means less time taken away from work, home and leisure activities, and the avoidance of the hassle of repeating the whole clinical course a few weeks later.

2. Speed in recovering functional vision

A much appreciated advantage is the rapid recovery of functional vision, with smoother adaptation to the new binocular vision and a faster return to daily activities. Indeed, when only one eye is operated on, the brain has to adapt to the imbalance between the treated and untreated eye, and many people feel frustrated by some of the adaptation phases, especially if it becomes difficult to read, drive and perceive depth with one eye operated on and one still with cataracts.

3. Less stress and waiting time

Surgery is never a walk in the park, even when it is as short and routine as cataract removal usually is. A single operating session for many patients can indeed be a relief, and in some cases, less stress can even aid the postoperative healing process.

One should then consider how the spread of the bilateral approach would have the advantageous consequence of drastically reducing waiting lists, with more than positive effects for all patients.

Immediate bilateral cataract safety

A key aspect of the clinical debate regarding immediate bilateral cataract concerns the safety of this approach, as simultaneous bilateral surgery could expose one to the risk of complications in both eyes at the same time.

As pointed out by the authors of the Moorfields Eye Hospital study, the immediate bilateral cataract procedure is considered safe when performed following very strict protocols. In particular, they recommend:

• Strict separation of sterile instruments to be used for each eye
• Independent surgical preparation for each eye
• In some cases presence of a double operating team
• Appropriate patient selection.

Conclusions

The choice of immediate bilateral cataract must be based on a thorough assessment of the individual patient.

Only patients who are in good systemic health, who do not have ocular comorbidities such as glaucoma and macular degeneration, and for whom bilateral cataracts do not pose an increased risk of complications, should be included.

Countless clinical studies confirm the safety profile of immediate bilateral cataracts, and in some countries such as Sweden, this procedure is favoured in one in five cataract surgeries as early as 2019.

In summary, immediate bilateral cataract now represents a new standard that would potentially be applicable to a large majority of patients, offering a more efficient and faster solution for restoring sight.

• https://www.theophthalmologist.com/issues/2025/articles/december/bilateral-benefits-uk-study
• Aiello F, Gallo Afflitto G, Leviste K, et al.Immediate sequential vs delayed sequential bilateral cataract surgery: systematic review and meta-analysis. J Cataract Refract Surg. 2023;49(11):1168-1179. doi:10.1097/j.jcrs.0000000000001230