BILATERAL SURGERY

Simultaneous bilateral endophthalmitis resulting in bilateral blindness is probably the most feared risk of immediate simultaneous bilateral cataract surgery (ISBCS). However, surgeons who cite this complication as the reason not to operate on both eyes at the same session should rethink their stance based on what is considered to be the best available evidence, according to a study presented at the XXXI ESCRS Congress in Amsterdam.

Olivia Li MD presented data estimating the risk of simultaneous bilateral endophthalmitis (SBE) after ISBCS and its visual prognosis. Risk was calculated using data on unilateral endophthalmitis from two large studies. Assuming adherence to principles of safe surgery, including use of intracameral antibiotics and full segregation of each procedure, it was estimated that SBE might occur in just one patient per 3.9 million ISBCS cases or more optimistically, in just one patient per 206 million cases of ISBCS.

The information on visual outcome was derived from a recent analysis of data collected in the Swedish National Cataract Register [J Cataract Refract Surg. 2013;39(1):15-21]. In the Swedish National study, there were 135 cases of postoperative endophthalmitis occurring over a six-year period, and 32.5 per cent of the eyes had a final distance BCVA of 20/40 or better. Integrating these data with the estimated risk of SBE, the chance of having bilateral BCVA worse than 20/40 after ISBCS would be approximately one in over nine million, said Dr Li, specialist trainee in ophthalmic surgery, Chelsea and Westminster Hospital NHS Foundation Trust, London, UK.

“Practical and procedural advances are continually being made to reduce complications from cataract surgery and we believe ISBCS has many benefits for patients, surgeons and healthcare budgets,” she said.

“There are other concerns about ISBCS that may still need to be addressed. However, we urge all cataract surgeons to consider the available information on the risks and merits of ISBCS, look beyond the rhetoric on SBE and offer their patients an informed discussion about immediate simultaneous procedures.”

In evaluating the risk of SBE following ISBCS, Dr Li noted that a review of the literature identified only four published cases.

“Importantly, details from these cases revealed that in each, there was breach of the aseptic protocols recommended by the Royal College of Ophthalmologists (RCO) in the UK and by the International Society of Bilateral Cataract Surgeons (iSBCS),” said Dr Li.

Due to the paucity of data on SBE, its risk was estimated by translating information on unilateral endophthalmitis risk. The two sources used were the ESCRS Postoperative Endophthalmitis study [J Cataract Refract Surg. 2007;33(6):978-88], in which the risk of unilateral endophthalmitis in eyes receiving intracameral cefuroxime was 0.05 per cent, and a report analysing the experience of iSBCS members, where the risk was only 0.007 per cent (a single case of endophthalmitis among 14,352 operated eyes) [J Cataract Refract Surg. 2011;37(12):2105-14].

Dr Li explained that assuming surgeons would follow guidelines from the iSBCS and the UK RCO to ensure that the bilateral surgeries were performed as completely separate procedures, the risk of both eyes becoming infected would be random events. Therefore, the risk of SBE could be calculated from unilateral risk data by taking the inverse of the squared value of the unilateral SBE rate [1/(0.00050582)2 = 1 case per 3.9 million ISBCS] using the ESCRS data and 1/(0.007)2 = 1 case per 206 million ISBCS procedures using the iSBSC data].

Dr Li compared the risk estimates for SBE and bilateral blindness after SBE with data showing a one in 100,000 risk of death following use of a general anaesthetic.

“Some patients choose to undergo cataract surgery using general anaesthesia, even in the absence of medical indications for its use,” said Dr Li, noting that ISBSCS also halves the risks of general anaesthesia.

Risk minimisation strategies

As underscored by the experiences in the four published reports of SBE, the development of endophthalmitis in both eyes after simultaneous surgery likely does not represent independent events. Rather, there are surgeon-related factors as well as patient-related features that link the two complications and attention to all of these issues is critical.

“Prevention is better than cure, and so with an aim to prevent endophthalmitis, surgeons must recognise the importance of careful case selection and adherence to the principles of safe ISBCS,” Dr Li said.

Patient features that increase susceptibility to infection include blepharitis, external colonisation by commensal organisms, compromised immune status and certain anatomical characteristics. These factors largely remain even if the patient undergoes delayed sequential surgery, where bilateral endophthalmitis remains a risk, though rarely considered. In all cases, any preexisting pathologies that predispose to infection should be managed preoperatively. Cases that are anticipated as being difficult with an increased chance for intraoperative complications that might increase the risk for endophthalmitis should generally be excluded from ISBCS, as well as anaesthesia that demands postoperative patching. And, when ISBCS is planned, patients should be counselled preoperatively that if any unexpected events occur during the first eye procedure, the second eye operation would be delayed.

Olivia Li MD: mail@olivia-li.com