Cataract Surgery · Surgeon Series
Two cataracts.
One visit. Two separate
operations.
Operating on both eyes in the same session is no longer unusual, but it only works when each eye is treated as if it belonged to a different patient. Here is what same-day bilateral cataract surgery actually is, what the evidence supports, who it suits, and what “separate sets” means in the operating room.
in ISBCS
that enters the eye
with intracameral cefuroxime
Section 01 — The Question
Why wait for the
second eye, if you don’t have to?
For decades the standard pattern was one eye, a healing interval of weeks or months, then the other. It was a sensible habit built on caution, and in many health systems it was also built on waiting lists. A growing number of surgeons now offer a different pattern: immediately sequential bilateral cataract surgery, or ISBCS, in which both eyes are operated on in the same session.
The key word is sequential. ISBCS is not one operation on two eyes. It is two complete operations, one after the other, with the first eye finished, dressed and protected before the second begins. Everything that touches the second eye — instruments, drapes, fluids, drugs, lens — is meant to be separate from what touched the first.
Same-day bilateral cataract surgery (ISBCS) means operating on both eyes in one session as two fully separate procedures. Its appeal is practical: fewer visits, no period of mismatched vision between eyes, and one recovery instead of two. Its risk is theoretical but serious: a single source of contamination could reach both eyes. The answer is the separate-set protocol, in which every instrument, solution, drug and implant for the second eye comes from different lots from those used in the first. ISBCS suits straightforward cases with predictable lens calculations. It is usually avoided when either eye looks complicated, or when seeing the first eye’s result would help choose the second lens.
Section 02 — Interactive
Two eyes, one gap,
and what they share.
Two things decide how ISBCS compares with waiting: the interval between the eyes, and whether the two operations share their supplies. Move the slider and switch the supplies below to see both.
Notice what the model does and does not claim. It does not put a number on infection risk, because no honest number can be read off a slider. What it shows is the logic of the protocol: the longer the gap, the longer the patient lives with mismatched eyes; and the moment the supplies are shared, the two eyes stop being independent, which is the one condition ISBCS cannot tolerate.
Section 03 — Why Surgeons Hesitated
The fear was never the
surgery. It was the shared source.
Cataract surgery is one of the safest operations in medicine, and its most feared complication, endophthalmitis, is rare. The hesitation about same-day surgery comes from one scenario: a rare event happening in both eyes at once.
Delayed surgery acts as a safety net. If the first eye develops a problem, the second is simply not operated on. With ISBCS that net is gone, so a problem with a shared cause could in principle affect both eyes before anyone knows. Isolated case reports of bilateral endophthalmitis, and clusters of bilateral toxic anterior segment syndrome (TASS) traced to a contaminated or mislabelled product, have been published. They are the reason the protocol insists on separate lots.
Meanwhile the baseline has fallen. The ESCRS multicentre study found that intracameral cefuroxime at the end of surgery lowered the endophthalmitis rate about five-fold, from roughly 0.25% in the control group to roughly 0.05%. Large later cohorts, including Herrinton and colleagues’ analysis of Kaiser Permanente cataract surgeries, supported the benefit of intracameral antibiotic prophylaxis. The wider story of prevention is covered in our endophthalmitis guide and the intracameral moxifloxacin guide.
setups per patient
shared between eyes
reduction, ESCRS study
Section 04 — The Evidence
What the studies
actually support.
The honest summary is that ISBCS is supported by large case series, registry experience and a small number of randomised trials, but not by a trial big enough to prove equal infection rates. The event is simply too rare for that.
| Source | Design | What it contributes |
|---|---|---|
| Arshinoff & Bastianelli, 2011 | Review of endophthalmitis after ISBCS across surgeons and centres | Concluded that endophthalmitis after ISBCS was uncommon when separate-set protocols were followed, and described the protocol in detail |
| Lundström et al., 2006 | Small randomised clinical study, same-day versus separate-day | Reported patient benefits in convenience and earlier visual rehabilitation without an evident safety penalty; too small to detect rare events |
| Sarikkola et al., 2011 | Randomised trial (Helsinki study), simultaneous versus delayed bilateral surgery | Compared clinical outcomes and patient-reported measures between the two approaches in a controlled setting |
| ESCRS Endophthalmitis Study Group, 2007 | Multicentre randomised trial of prophylaxis | Established intracameral cefuroxime as a major reducer of endophthalmitis, the baseline against which ISBCS safety is argued |
| Herrinton et al., 2016 | Large cohort comparing antibiotic prophylaxis strategies | Supported the protective effect of intracameral antibiotic in routine practice |
Two cautions apply when reading this literature. First, studies of ISBCS describe selected patients and surgeons who follow strict protocols; the findings should not be extended to same-day surgery performed with shared supplies. Second, the figures in these papers vary by country, antibiotic and definition, so quoting a single rate for “ISBCS endophthalmitis” would be false precision. Where this guide gives numbers, it uses only the widely cited ESCRS figures and says so.
Section 05 — Who Qualifies
Good candidates,
and the cases to avoid.
Same-day surgery works best when nothing about either eye needs a second look. The more a case depends on learning from the first operation, the stronger the argument for waiting.
| Factor | Favours ISBCS | Favours waiting |
|---|---|---|
| Surgical complexity | Both eyes routine, good dilation, moderate cataract density | Small pupil, white or very dense cataract, pseudoexfoliation or weak zonules (see capsular tension rings) |
| Lens power prediction | Average axial length, no prior refractive surgery | Very long or short eyes, prior LASIK or PRK, where a refractive surprise is more likely |
| Lens choice | Standard monofocal or well-understood design | First-time premium, toric or extended-depth lens, where the first eye teaches what the patient tolerates |
| Eye health | No active inflammation, healthy cornea and retina | Uveitis, corneal dystrophy, macular disease, prior intraocular surgery |
| Practical need | Long travel distance, dependence on an escort, anaesthesia or mobility constraints | Patient prefers to see the first result, or is anxious about two operations at once |
| Setting | Theatre able to deliver truly separate sets and record lots | Environment where supplies or staff cannot be separated |
A complication in the first eye is itself a reason to stop. Protocols describe a clear rule: if the first eye does not go smoothly, for example posterior capsule rupture, the second operation is postponed.
Section 06 — The Protocol
What “separate sets”
actually means.
Published ISBCS protocols, including those described by Arshinoff and colleagues, are specific. They do not just ask for “clean technique”; they list what must differ between the first and second eye.
| Item | Requirement for the second eye |
|---|---|
| Instruments and handpiece | Separate sterilised tray; separate phaco handpiece, tubing and cassette |
| Preparation and draping | Fresh skin and conjunctival preparation; new drape; gloves and gown changed |
| Irrigating solution | Different bottle and lot of balanced salt solution |
| Viscoelastic (OVD) | New syringe from a different lot from the first eye |
| Intracameral drugs and dyes | Antibiotic, miotic and capsule dye drawn from different vials or lots |
| Intraocular lens | Separate implant and packaging, recorded by lot |
| Documentation | Lot numbers for every product recorded in the chart for each eye |
| Postoperative plan | Both eyes checked at the first review, with a plan for urgent warning signs |
The documentation line matters as much as the physical separation. If something goes wrong in one eye, separate lot records let the team see immediately whether the other eye received any common product, and what to do about it. The same principle applies to viscoelastic devices and trypan blue: they are used on both eyes, but never from the same container or batch.
Section 07 — Putting It Together
One route, two ways
the decision plays out.
A patient with symmetric, moderate cataracts, average eye measurements and no other eye disease lives a long way from the surgical centre and needs a relative to travel with them. Two separate trips would mean two sets of travel, two days off work for the escort, and weeks of mismatched vision in between. For this patient ISBCS removes a real burden, and nothing about their eyes asks for a second look. The surgeon books both eyes in one session, with separate sets and recorded lots, and a plan to postpone the second eye if the first does not go smoothly.
A patient who had myopic laser vision correction years ago has two cataracts and wants to be glasses-free. Lens power calculation after corneal laser surgery is less predictable, and a refractive surprise in one eye would be repeated in the other if both were operated on together. Here, doing the first eye and measuring the healed result before choosing the second lens is plainly the safer plan. This is a case where waiting is a feature, not a delay.
For an overview of what recovery looks like after a single eye, see the week-by-week recovery guide. After ISBCS the same timeline applies to both eyes at once.
Section 08 — The Agaaz Range
Two eyes means two sets
of everything.
Agaaz Ophthalmics does not make anything specific to ISBCS, and the protocol does not need special products. What it needs is more of the ordinary ones, kept strictly apart. For a surgical centre or a distributor supplying one, that is a purchasing, stocking and traceability question rather than a product question.
For distributors and procurement teams: ask each supplier for lot-level batch documentation with every shipment, and plan stock so that a centre can allocate different lots to the two eyes on the same day. View the complete portfolio →
Section 09 — FAQ
Frequently asked questions
about same-day cataract surgery.
For carefully selected patients, large case series, registry experience and small randomised trials have reported that immediately sequential bilateral cataract surgery (ISBCS) can be performed with complication rates comparable to single-eye surgery, provided each eye is treated as a completely separate operation. It is not risk-free, and no trial is large enough to prove equal endophthalmitis rates, because the event is too rare. Whether it is appropriate for you is a decision for your surgeon after a full eye examination.
In immediately sequential bilateral cataract surgery (ISBCS), both eyes are operated on during the same session, one after the other, as two independent operations. In delayed sequential bilateral cataract surgery (DSBCS), the second eye is done on a separate day, anywhere from a few days to several months later. The surgical technique is the same; the difference is the interval, the number of visits, and whether the result in the first eye can inform the plan for the second.
That is the central concern, and it is why ISBCS protocols exist. Two eyes only have independent infection risks if they do not share a source of contamination. Published ISBCS protocols therefore use separate instruments, separate skin preparation and draping, and separate batches of every fluid and drug that enters the eye, with lot numbers recorded for each eye. Intracameral antibiotic prophylaxis, which lowered endophthalmitis roughly five-fold in the ESCRS study, adds a further layer of protection.
Surgeons generally avoid ISBCS when either eye is expected to be complicated: pseudoexfoliation or weak zonules, a small or poorly dilating pupil, a very dense or white cataract, prior eye surgery, active inflammation, or significant corneal or retinal disease. It is also usually avoided when the lens power is difficult to predict, such as after previous laser vision correction or in very long or short eyes, and when a patient would benefit from seeing how the first eye turns out before choosing a lens type for the second.
The main reasons are information and caution. After the first eye heals, its actual refractive result can be used to fine-tune the lens power chosen for the second, which is not possible in same-day surgery. Waiting also means that a problem in the first eye is known before the second is operated on. Local reimbursement rules, operating-list structure and tradition also keep delayed surgery the default in many countries.
It means the second eye is treated as if it were a different patient. The instrument tray, phaco handpiece and tubing, drapes, gloves and gown are changed; the skin and conjunctiva are prepared again; and the balanced salt solution, viscoelastic, intracameral drug, dye and lens come from different lots from those used in the first eye. The lot numbers for each eye are written in the chart so that any problem can be traced to a single batch.
Often yes. Once the first eye has a new lens and the second still has a cataract, the two eyes can have very different prescriptions (anisometropia) and sizes of retinal image, which can make glasses uncomfortable and affect depth perception. Surgeons manage this by keeping the interval short or by using a contact lens or lens-free spectacle option. ISBCS removes this gap, which is one of its practical attractions.
References & Evidence Base
Peer-reviewed
citations.
Each link opens a PubMed search for the paper’s title.
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