Immediate Sequential Bilateral Cataract Surgery (ISBCS): Evidence and Safe Protocol
Last updated: October 2026
Immediate sequential bilateral cataract surgery (ISBCS) means operating on both eyes in the same session, as two completely separate procedures. Once considered reckless because of the fear of bilateral endophthalmitis, it is now routine in parts of Europe and Canada and growing elsewhere. The evidence is reassuring, but only when strict safety rules are followed.
Why do it, and what worries people
| Potential advantages | Concerns |
|---|---|
|
|
What the evidence shows
| Source | Finding |
|---|---|
| Cochrane review (2022): 14 studies, about 276,000 participants | Outcomes probably do not differ in a clinically meaningful way. Refraction within 1 D of target was similar. Endophthalmitis was very rare in both groups (1 in 14,076 with ISBCS vs 55 in 556,246 with delayed surgery), with no evidence of higher risk. Costs were lower with ISBCS. Certainty ranged from moderate to very low. |
| AAO IRIS Registry: 1.8 million bilateral surgeries | ISBCS eyes had slightly worse uncorrected acuity than eyes operated 15–90 days apart (2.8 and 1.7 letters fewer). The difference is small and probably reflects case selection rather than the approach itself. |
| Swedish National Cataract Register | Postoperative endophthalmitis was less frequent after ISBCS (about 1 in 6,600) than after delayed surgery (about 1 in 3,345), in a setting with routine intracameral antibiotics. |
| iSBCS society data: about 125,000 eyes | Endophthalmitis about 1 in 16,800 with intracameral antibiotics. |
The safety rules: treat each eye as a separate operation
- The first eye must be completely uncomplicated. If anything goes wrong (posterior capsule rupture, dropped nucleus, unexpected findings), do not proceed to the second eye that day.
- Full separate preparation and draping for the second eye. The surgeon re-scrubs, or at least re-gowns and re-gloves.
- Separate instrument sets for each eye, sterilised in separate cycles where possible.
- Different manufacturing lots of fluids, viscoelastics and intracameral drugs for each eye where possible, to avoid a bilateral contamination or TASS event.
- Intracameral antibiotic (for example moxifloxacin or cefuroxime) in both eyes. Not using it is a recognised risk factor for endophthalmitis.
- A surgeon and team with a low, audited complication rate in routine phaco.
Choosing patients
- Good candidates: routine bilateral cataracts with reliable biometry, and patients for whom extra visits or anaesthetics are a real burden.
- Be cautious or avoid while you gain experience: unreliable biometry (high axial myopia or hyperopia, previous refractive surgery) where the first eye's outcome would guide the second; uveitis; diabetic macular oedema; active blepharitis or chalazia; Fuchs dystrophy with thick corneas; severe pseudoexfoliation; colobomas.
- Consent should cover bilateral risks explicitly and offer delayed surgery as an alternative.
Viva pearls
- ISBCS (same session, separate procedures) is not the same as simultaneous bilateral surgery (both eyes as one procedure, which is unacceptable).
- The two key safeguards are aseptic separation and intracameral antibiotics.
- Different lot numbers matter most for TASS, which is bilateral if the same contaminated batch is used.
- Delayed sequential surgery lets you adjust the second IOL from the first eye's refractive result, which is the main optical argument against ISBCS.
Related: endophthalmitis, refractive surprise after cataract surgery and biometry rules of thumb.
Key sources
- Dickman MM et al. Cochrane review: ISBCS vs delayed sequential surgery (2022)
- Healio: IRIS Registry comparison of immediate vs delayed surgery
- Ophthalmology Times: optimising the implementation of ISBCS
📘 Want more exam-ready material? See Most Commons in Ophthalmology on Kindle, or browse all my books.
Looking for an eye specialist in Ahmedabad? Read about cataract surgery at Sadbhaav or book a consultation with Dr. Dhaval Patel.
