Same-Day Cataract Surgery on Both Eyes (ISBCS): A Surgeon's 2026 Guide

Immediately sequential bilateral cataract surgery (ISBCS) means having cataract surgery on both eyes on the same day, with the second eye treated as a completely separate operation: new prep, new drape, new instruments, and medications from different lots. Most US surgeons still operate one eye at a time, a few weeks apart. In Medicare fee-for-service data from 2018 to 2022, only 0.33 percent of patients who had both eyes done had them done the same day (Ali, JCRS 2025). Large registries now show that, in carefully selected patients, same-day surgery has infection rates and visual results comparable to staged surgery. This guide explains who is a good candidate, who is not, and what the day actually looks like.

What is immediately sequential bilateral cataract surgery?

In ISBCS, the surgeon removes the cataract from one eye, finishes that operation completely, and then starts the second eye as if it were a new patient arriving in the room. The defining feature is separation. The principles published by the International Society of Bilateral Cataract Surgeons in 2009 call for the two eyes to be kept completely separate, and they strongly recommend an intracameral antibiotic in each eye (iSBCS General Principles for Excellence in ISBCS, 2009). In practice, that means:

• A fresh surgical scrub and new gloves and gown for the second eye.
• A separate povidone-iodine prep and a new sterile drape.
• A separate, freshly opened instrument tray, never instruments carried over from the first eye.
• Irrigation fluid, viscoelastic, and intracameral medications from different manufacturing lots where possible.
• A separate surgical time-out confirming the eye, the lens, and the lens power.

That protocol is what distinguishes ISBCS from older approaches in which both eyes were operated on as a single case with shared instruments or supplies. That approach is not acceptable by modern standards, and it is not what anyone should mean by same-day bilateral surgery today. The protocol also answers a common question: if anything unexpected happens in the first eye, the second eye is simply postponed.

Why US surgeons have usually operated one eye at a time

There are three historical reasons, and they are all reasonable.

Infection risk. Endophthalmitis after cataract surgery is rare but can cost vision. The feared worst case of ISBCS is an infection in both eyes at once. Staging the eyes weeks apart makes that practically impossible.

Learning from the first eye. With staged surgery, the surgeon can measure how the first eye healed and refine the lens power for the second. This matters most in eyes where lens calculations are less predictable.

Payment and habit. The American Academy of Ophthalmology notes that ISBCS is not commonly performed in the United States and lists Medicare's reduced payment for the second eye among the barriers (AAO Preferred Practice Pattern, Cataract in the Adult Eye, 2021). Surgeon training, facility scheduling, and patient expectations all play a part too.

What the evidence now shows

The picture has changed because very large data sets now exist.

• US IRIS Registry, 165,609 ISBCS patients. The endophthalmitis rate was 0.059 percent after same-day surgery and 0.056 percent after staged or single-eye surgery, a difference that was not statistically significant. There were no bilateral infections after ISBCS (Lacy, Ophthalmology 2022).
• Swedish National Cataract Register, 92,238 ISBCS procedures. Endophthalmitis occurred in 0.0152 percent of same-day procedures and 0.0299 percent of single-eye procedures (Friling, Ophthalmology 2022).
• Pooled international data, 95,606 ISBCS cases. No bilateral simultaneous endophthalmitis was reported (Arshinoff, JCRS 2011).
• Kaiser Permanente, more than 3,500 ISBCS patients. Visual and refractive outcomes matched staged surgery, with 63 percent of same-day eyes and 61 percent of staged eyes ending up emmetropic, meaning without meaningful residual prescription (Herrinton, Ophthalmology 2017).
• Cochrane review, 2022. The authors concluded there are probably no clinically important differences in outcomes between same-day and staged surgery, at lower cost, while rating the certainty of the evidence as low for rare complications (Dickman, Cochrane 2022).

The data are not uniformly positive. An IRIS Registry analysis found visual acuity after ISBCS was about 1.6 to 2.8 letters worse on an eye chart, a difference the authors said may or may not be clinically relevant (Owen, JAMA Ophthalmology 2021). The fair summary is non-inferiority for selected patients, not superiority. In some countries it has become routine: one Finnish eye center went from 4.2 percent same-day surgery in 2008 to 46 percent in 2020 (Hujanen, Br J Ophthalmol 2023). The Royal College of Ophthalmologists and the Canadian Ophthalmological Society both published ISBCS guidance in 2020.

Am I a candidate for same-day bilateral cataract surgery?

The AAO's guidance is that individual patient preferences and the best interests of the patient's visual health and refractive status should be the predominant factors in the decision. Candidacy is a conversation, not a checkbox. Guidance endorsed by the Canadian Ophthalmological Society lists many of the factors below (COS-endorsed ISBCS guidance, 2020).

You are likely a good candidate if:

• You have visually significant cataracts in both eyes and want both treated. If you are unsure about the cataract symptoms in your second eye, that is worth settling first.
• Your eyes are otherwise healthy and similar in length, with reliable measurements.
• You are choosing a standard monofocal or toric monofocal lens with a predictable calculation.
• Travel, caregiving, or medical factors make two separate surgery days, and two sets of pre- and post-operative visits, a real burden.

We would want to talk more if:

• You have had LASIK, PRK, or radial keratotomy, or your eyes differ in length by more than about 1 mm, which makes the lens calculation less certain.
• You have a very short or very long eye, a history of floppy iris syndrome, or mild zonular weakness.
• You want a trifocal or a light adjustable lens and would benefit from experiencing the first eye before committing the second.
• You have diabetes that is poorly controlled, take immunosuppressive medication, or have active blepharitis, all of which raise infection concern.

This is probably not the right option if:

• You feel uncertain or pressured. Freely choosing same-day surgery is a basic requirement.
• Either eye is a complex case: very dense cataract, loose lens support, moderate to severe pseudoexfoliation, posterior polar cataract, Fuchs dystrophy, advanced glaucoma, uveitis, or active retinal disease.
• You rely on one eye far more than the other, or cannot manage a short period of blur in both eyes.

How the surgery day works

You check in once, receive one set of preoperative drops, and the anesthesia team sets up once. The first eye is operated on in the usual way; see our cataract surgery anesthesia guide for what sedation feels like. Between eyes, the surgical team re-scrubs and resets the field with new instruments while you rest. The second eye takes about as long as the first. If you are having femtosecond laser cataract surgery, the laser portion is performed for each eye as well; our comparison of femtosecond laser vs traditional phacoemulsification covers when that step adds value.

Before you go home, both eyes are checked. Most surgeons shield both eyes or at least the second eye for the ride home, so plan for a driver and someone to help you that evening. Your drop schedule then covers both eyes, which means one bottle schedule instead of two overlapping ones.

Infection safety: why the protocol matters

Endophthalmitis is uncommon after any cataract surgery. In US IRIS Registry data from 2013 to 2017, the rate was about 0.04 percent, or roughly 1 in 2,500 eyes (Pershing, Ophthalmology 2020). Rates are lower where an antibiotic is placed inside the eye at the end of surgery. In the ESCRS randomized trial of more than 16,000 patients, eyes that did not receive intracameral cefuroxime had close to five times the risk (ESCRS Endophthalmitis Study Group, JCRS 2007), and the Aravind Eye Hospital system reported a drop from 0.07 to 0.02 percent after adopting intracameral moxifloxacin (Haripriya, JCRS 2019).

The key question for ISBCS is whether a single contamination event can reach both eyes. A 2022 review found only seven published cases of bilateral simultaneous endophthalmitis in 50 years, nine including cases reported elsewhere, and the separate-eye protocol had generally been breached or was uncertain in those cases (Chen, JCRS 2022). Separate lots also protect against toxic anterior segment syndrome (TASS), a sterile inflammation caused by a contaminated solution or instrument, which the AAO lists alongside infection as the main bilateral risk. That is why the separate trays, separate lots, and intracameral antibiotic in each eye are not optional details. They are the reason ISBCS is defensible. If the protocol cannot be followed, the eyes should be staged.

Choosing a lens when both eyes are done the same day

Monofocal and toric monofocal lenses are the most straightforward, because modern biometry predicts them well in typical eyes. EDOF and trifocal lenses can be implanted the same day, and some patients value adapting to matched vision all at once. The trade-off is that you cannot try the first eye before committing the second, which matters most with trifocals, where night halos vary from person to person. Our guide to PanOptix, Vivity, and Symfony compared explains those differences.

The Light Adjustable Lens can be placed in both eyes, with the UV adjustments done afterward. Mixed plans, such as a distance-focused lens in one eye and an extended-range lens in the other, are also possible. Still, the more a plan depends on how the first eye turns out, the stronger the case for staging.

How does the surgeon choose the second lens without seeing the first result? The same way the first lens is chosen: from careful measurements and a modern formula. In a large trial cited by the AAO, the second lens was changed in about 5 percent of staged patients, yet second-eye results did not differ. The Cochrane review found no difference in the share of eyes ending up more than 1.0 diopter from target.

What ISBCS costs and how Medicare pays

For patients with Original Medicare, the usual rules apply: the Part B deductible, $283 in 2026, and then generally 20 percent of the Medicare-approved amount (CMS 2026 Part B fact sheet). What changes is how Medicare pays the providers. Under the 2026 Physician Fee Schedule, cataract surgery codes carry a bilateral payment indicator, so the surgeon is paid 150 percent of the single-eye fee for both eyes on the same day. The surgery center is paid in full for the first eye and 50 percent for the second (Medicare Claims Processing Manual, Chapter 14). Your coinsurance is based on those approved amounts.

Premium lens and astigmatism upgrade charges are billed per eye exactly as they are with staged surgery. They remain non-covered, patient-pay charges under CMS rulings 05-01 and 1536-R. Our guide on how Medicare pays for premium IOL upgrades covers the details. Medicare Advantage and Medigap plans follow their own rules, so confirm coverage before scheduling.

Recovery after same-day bilateral cataract surgery

Recovery for each eye follows the usual cataract surgery recovery timeline. The difference is that both eyes heal at once.

• Day of surgery: both eyes are blurry and light sensitive. Rest, use your drops, and have help at home.
• Day 1: most patients see noticeably better, though not yet sharply. A first postoperative check is usually scheduled.
• Week 1: vision is usually good enough for most daily tasks. Many patients are cleared to drive once both eyes meet the legal standard.
• Weeks 4 to 6: healing is largely complete, and a final glasses check can be done for both eyes at the same visit.

The main adjustment is that you do not have a "good eye" to rely on for the first day or two. Most patients describe it as looking through a foggy window that clears quickly. Know the difference between normal cataract surgery side effects and warning signs, and call your surgeon the same day if pain or blur gets worse instead of better. If you are weighing timing more broadly, our article on how long to wait between eyes covers the staged approach.

Not every surgeon offers ISBCS, and that is a legitimate choice. Ask whether it is right for your eyes. To compare surgeons, you can find a fellowship-trained cataract surgeon near you or browse top-rated cataract surgeons by patient reviews and experience.

Frequently asked questions

Why don't more US surgeons do same-day bilateral cataract surgery?

Habit, training, facility logistics, and payment all play a role. Surgeons also value refining the second lens after seeing the first eye heal. The AAO notes that ISBCS is not commonly performed in the United States and names Medicare's reduced payment for the second eye as one barrier, not the only one.

What if something goes wrong with the first eye during the operation?

Then the second eye is postponed. The international ISBCS principles call for deferring the second eye whenever the first has an unresolved complication. Because every step is set up as a separate operation, stopping after one eye is simple, and you would have the second eye done later as a staged procedure.

Is ISBCS safe if I need a toric IOL or PanOptix?

A toric monofocal lens is usually straightforward to place in both eyes the same day. Trifocals such as PanOptix are possible, but you lose the chance to experience the first eye before choosing the second. Many surgeons prefer staging when a patient is uncertain about multifocal halos.

Does Medicare cover same-day bilateral cataract surgery?

Yes. Medicare covers medically necessary cataract surgery whether the eyes are done on the same day or separately. You pay the $283 Part B deductible in 2026 and generally 20 percent coinsurance. Premium lens and astigmatism upgrade fees are patient-pay and billed per eye, as with staged surgery.

Can I go home the same day?

Yes. ISBCS is outpatient surgery, and patients go home the same day after both eyes are checked. Because both eyes are blurry at first, you need a driver and ideally someone to help you that evening. Most patients see noticeably better by the next morning.

How is the second eye's lens power calculated without the first eye's result?

The same way the first is: from optical biometry and a modern lens formula. In typical eyes these predictions are accurate, and the Cochrane review found no difference in how often eyes missed their target by more than 1.0 diopter. In eyes with prior LASIK or unusual length, staging is often wiser.