Whilst endophthalmitis following cataract surgery can lead to serious vision outcomes, there are ways of minimising the risk of it occurring whilst also being mindful of the need to prescribe antibiotics in a way that does not worsen antimicrobial resistance.
Cataract surgery is performed more often than any other surgery in Europe, with the use of prophylactic antibiotics procedures being commonplace. Whilst such drugs are vital for preventing and treating infection, the antimicrobial resistance crisis threatens to undermine the progress that has been made in preventing deaths from infection and has become an urgent healthcare priority.
I asked ophthalmologist Dr Marco Coassin to tell me more about endophthalmitis, a type of inflammation of the internal eye tissues that can occur due to infection, and the delicate balance between minimising the risk of postoperative infection and taking responsibility for helping to manage and reduce antibiotic resistance.
Whilst I do not believe that patients should be worried about developing endophthalmitis, they do need to be aware of this sight-threatening disease, even if the chances of developing it after cataract surgery are statistically low. According to various reports, the incidence of postoperative endophthalmitis is in the range of 0.03–0.7%: as a surgeon, I might see one endophthalmitis case per every 1,000 cataracts I operate on.
The problem is that patients are often unaware that, even if rare, endophthalmitis might occur in perfectly operated eyes – and be devastating for their vision. This may be due to the unwillingness of doctors to worry their patients before an otherwise straightforward surgery.
A surgeon’s overconfidence may play a role too: a “this is not going to happen to me” kind of attitude is not uncommon for those who perform hundreds of operations each year. This pairs with the very high expectations that patients now have towards modern cataract surgery. They expect a rapid, simple procedure, resulting in crystal clear postoperative vision.
The main causative agents in post-cataract endophthalmitis are common bacteria that may normally be found in the ocular surface and periocular tissues. They may enter the eye through the surgical incision used to remove the cataract and cause massive, uncontrollable intraocular inflammation.
Gram-positive bacteria such as Staphylococci account for up to 94% of the cases. Symptoms may start within 3 days after the surgery and include rapid worsening of visual acuity, ocular pain and discharge. Signs include conjunctival hyperaemia, corneal oedema, anterior and posterior intraocular inflammation with hypopyon, vitritis and retinal alterations.
Diagnosis may be cumbersome and requires invasive procedures for collecting specimens for microbiologic cultures. And treatment may be painful and require intraocular injections or vitreoretinal surgery.
The outcomes can be quite dramatic. Only half of the infected eyes retain a visual acuity of better than 20/40 and up to one third will end up with extremely poor vision (worse than 20/200). We know that certain pathogens, such as Streptococci and Gram-negative bacteria, are related to worse visual outcomes. Older individuals, patients with diabetes or those with other severe systemic comorbidities usually have the poorest prognosis.
There are four approaches I take to reduce the chance of endophthalmitis occurring in my cataract patients. Firstly, I rely on pharmacological prophylaxis: the ESCRS endophthalmitis study1 demonstrated that intracameral cefuroxime at the end of surgery dramatically reduces the risk of intraocular infection. The addition of postoperative antibiotics in the form of eye drops can help lower the incidence of endophthalmitis even further.
Secondly, since corneal wound leakage is a leading factor for postoperative infection, I am very meticulous in correctly shaping corneal incisions and in carefully sealing them at the end of cataract surgery. Thirdly, I identify patients who might be at higher risk for infection, such as those with immunosuppression, diabetes or intraoperative complications. And finally, I carefully monitor patients’ postoperative behaviour.
We need to be aware that our small actions—routinely prescribing antibiotic eye drops after cataract surgery—may have a huge impact in terms of global health. More than 4 million cataract surgeries are performed each year in Europe. Since virtually all cataract surgeons use intra- or postoperative antibiotics, it is calculated that this amounts to more than 60 million days per year of antibiotic exposure. If the way we use antibiotics does not improve, it has been estimated that 10 million people will die as a consequence of antimicrobial resistance by 2050.
We should use the antibiotic that has the largest spectrum of action and prescribe the shortest duration of therapy. Efficiently and rapidly eliminating the pathogen reduces the risk of developing resistance. I personally use levofloxacin four times a day for one week, usually in fixed combination with dexamethasone.
After one week, I then prescribe dexamethasone alone or a different anti-inflammatory eye drop. You do not need more than one week of antibiotic after surgery and tapering the antibiotic does not make any sense: it just increases the risk of resistance.