Some surgeons have embraced immediate sequential bilateral cataract surgery for its rapid visual rehabilitation and practical ease for elderly patients, performing it on request in the absence of contraindications. It can offer superior short-term visual outcome compared with delayed sequential surgeries and can be performed safely with no significant difference in long-term complications or visual outcome. Immediate sequential surgeries also offer significant financial savings in an era when economization is perceived as paramount. Some regions, such as the Canary Islands of Spain, perform 80% of all cataract surgeries in this way with explicit government approval. Patient satisfaction can be high, with 91% willing to recommend it to their friends and family.

Despite this, many cataract surgeons, notably in the United States, do not offer immediate sequential bilateral cataract surgery, with the principle objection being the risk of simultaneous bilateral endophthalmitis. Financial penalties to the surgeon also doubtlessly can influence decisions. Reimbursement for same-day second eye surgery varies greatly, from 50% by Medicare and Medicaid in the United States, to no reimbursement in Japan and Israel. A survey of American Society of Cataract and Refractive Surgeons members in 2012 revealed that only 0.9% perform bilateral or same day cataract surgery most of the time, yet 16.3% always try to implant a phakic intraocular lens bilaterally at the same event.

Simultaneous bilateral endophthalmitis is undeniably frightening with a potentially devastating outcome. However, the factual risk is poorly known to most ophthalmologists, who consequently fail to offer a choice to those patients suitable for bilateral surgeries.

With continuing advances and unrelenting pressures of an ageing population, ophthalmologists should know the true risk to enable responsible and evidence-based discussion with patients. This risk analysis should be based on best available current data from surgeons taking all appropriate measures to minimize infection.

There have been 4 cases of simultaneous bilateral endophthalmitis ever published. All breached the aseptic protocol published by the International Society of Bilateral Cataract Surgeons and the United Kingdom Royal College of Ophthalmologists. In 95 606 immediate sequential bilateral cataract surgeries (191 212 eyes) reported recently, there was no bilateral endophthalmitis. The unilateral endophthalmitis rate was 1 in 14 352 (0.007%) when intracameral antibiotics were used. The Swedish national study of the country’s endophthalmitis rates from 2005 through 2010 (464 996 surgeries) showed an infection rate of 0.029%, lower than that of the European Society of Cataract & Refractive Surgeons endophthalmitis study (0.062%).

In the absence of data for bilateral endophthalmitis after correctly performed bilateral surgeries, we turned to unilateral endophthalmitis data. Assuming segregation protocols are adhered to rigorously, it follows that the 2 surgeries may be regarded as largely independent events and no different than if the patient were to have delayed sequential surgeries, where bilateral endophthalmitis is also a risk—although rarely, if ever, considered. Similarly, factors predisposing patients to infection, such as diabetes and commensals, usually remain, despite temporal separation. Thus, using Swedish data on unilateral endophthalmitis, the risk of bilateral endophthalmitis, simultaneous or otherwise, would be in the region of 0.029% × 0.029%, equivalent to 0.00000841%, or 1 in 11.9 million bilateral surgeries (23.7 million eyes). If data from the largest series of immediate sequential bilateral cataract surgery are used, this figure becomes 1 in 206 million bilateral surgeries. As a comparator, the risk of death after a general anaesthetic is in the region of 1 in 100 000, yet many patients accept that risk to undergo nonessential medical procedures.

It is not simply simultaneous bilateral endophthalmitis that frightens ophthalmologists; it is the potential for functional blindness. Indeed, the two (bilateral endophthalmitis and blindness) are often assumed to be synonymous. With prompt modern management, this is not the case. Recent data reveal that approximately one third of eyes with endophthalmitis achieve final acuity of 0.3 logarithm of the minimal angle of resolution units (LogMAR) or better. Using this information, the potential risk of simultaneous bilateral endophthalmitis with final vision of worse than 0.3 LogMAR is approximately two thirds the risk of simultaneous bilateral endophthalmitis. Assuming 3 million cataract surgeries annually in the United States, and with the admittedly unrealistic postulate that all were undertaken as immediate sequential bilateral cataract surgery, this would equate to 1 patient having vision in both eyes worse than 0.3 LogMAR as a result of bilateral endophthalmitis every 59 to 1030 years.

An important point that should be considered when interpreting these figures is that the calculation of the number of people required to observe a case of bilateral endophthalmitis involves the inversion of the risk of unilateral endophthalmitis squared. Because the risk of unilateral endophthalmitis is very low, small changes in its absolute scale (as opposed to a relative change) may inflate or shrink considerably the number of years expected to observe a case of bilateral endophthalmitis. Nevertheless, even when the higher rates of endophthalmitis are used, the risk of bilateral endophthalmitis is estimated to be 26 times smaller compared with the risk of death after a general anaesthetic. Using the data from the largest bilateral series, this figure becomes 2060 times smaller than the risk of death after a general anesthetic.

Although the risk of bilateral endophthalmitis can never be truly independent of events, the protocols referred to above go to great lengths in segregating the procedures to reduce infection. In doing so, the risk of toxic anterior segment syndrome (TASS) also should be mitigated. Unlike endophthalmitis, TASS is a sterile inflammatory reaction and can be caused by contaminated instruments, phacoemulsification machines, irrigating fluids, and incorrect preparation of intracameral antibiotics. The use of pre-prepared intracameral antibiotics should help to reduce this risk by minimizing errors in mixing and diluting antibiotics in the perioperative period. We found 1 case of bilateral TASS after bilateral cataract surgery. The 2 surgeries were performed 1 day apart, with no causative factor for TASS found. This suggests that temporal segregation is insufficient to prevent bilateral TASS, and thus should not be a reason to dissuade surgeons from offering patients the choice of immediate sequential surgeries.

In electing to have immediate sequential surgeries, patients are unable to benefit from use of fellow eye intraocular lens calculation to predict the most suitable lens for the second eye. Although second eye lens choice may be influenced using fellow eye data, studies have demonstrated comparable final visual outcome in immediate sequential surgery compared with delayed surgery. Caution should be exercised in patients prone to unreliable biometric measurements, such as those with short and long axial lengths and who have undergone previous refractive surgery. Moreover, concurrent relevant ocular and periocular disease should be managed before surgery, and bilateral surgeries should be avoided in patients at higher risk of infection, such as those who are immunocompromised or have poorly controlled diabetes. Patients should not be patched after surgery, and thus must be suitable for appropriate anaesthesia to allow this. Patients also should understand that the second eye surgery may be delayed should any complication occur with the first eye.

Given the escalating burden of the cost of healthcare and the ever-growing competing demands on limited resources, we believe the risk of functional blindness is so very low as to justify the widespread introduction of immediate sequential bilateral cataract surgery. We are aware that some centers already have taken this step.