Endophthalmitis remains one of the most feared complications after any surgical procedure that enters the eye, and to me, an intravitreal injection is a surgical procedure. It is interesting that our retina colleagues who perform most intravitreal injections have now surpassed their cataract surgeon colleagues in frequency of surgical invasions into the eye per year. In addition, intravitreal injections are growing at a more rapid rate than cataract surgery.
Both cataract surgery and intravitreal injections put the patient at risk for infectious and noninfectious endophthalmitis. The risk found in one meta-analysis reported by Colin McCannel, MD, was 52 cases of endophthalmitis in 105,536 injections. Half were culture positive, and half were culture negative. The most common organism was Staphylococcus and second was Streptococcus. This is an incidence of about 1:2,000 injections. This is slightly lower than the incidence in cataract surgery, which approximates 1:1,000 when intraoperative intraocular antibiotics are not used. In addition, the most common organism is the same, Staphylococcus. The likelihood of a streptococcal infection is higher, however, after an intravitreal injection, and a gram-negative rod such as Escherichia coli or Pseudomonas aeruginosa is more common after cataract surgery.
It makes sense that the same approaches to prophylaxis should be effective. The most effective agent remains a good ocular and lid prep with Betadine solution (povidone-iodine). In my opinion, we need some commercial advances in Betadine solution, which commonly comes in a 10% solution that is very irritating to the eye. We can dilute it, and we have a 5% solution from Alcon, but it also burns and irritates the eye and comes in a larger bottle than necessary for an office injection. The infectious disease literature supports even lower concentrations of Betadine as being effective and less toxic. A 1% solution for single use in a 10 mL bottle would be attractive.
Isolation of the lashes and lid margins from the surgical entry point is another important area. This is most easily done for intravitreal injections with gloved fingers or a solid bladed speculum. Plastic drapes are essential in cataract surgery because the procedure is longer and many instruments pass over the lids, but they are not necessary in an intravitreal injection, which is quick and localized. The next most helpful adjunct is good hand washing or today, for most, “foaming in and foaming out” between every patient and before and after every procedure. No one would do cataract surgery without a cap, a mask, scrubs, a gown and gloves. Even when doing LASIK and minor extraocular procedures such as superficial keratectomy and collagen cross-linking, I wear scrubs, a cap, a mask and sterile gloves. These protect both the patient and the surgeon. I would lean toward a scrub suit, a cap, a mask and sterile gloves for an intravitreal injection.
As medical students, we all touched a culture plate with our hands and talked or coughed into a culture plate, which always revealed exuberant microbial growth in rapid order. It is often necessary for the doctor to talk to the patient during a treatment and touch instruments and often the patient. So, while I would lean toward wearing scrubs, a cap, a mask and sterile gloves for intravitreal injections, the consensus panel felt a simple “no talking,” and I presume “no breathing,” approach was adequate.
Both the cataract literature and the intravitreal injection literature lack good support for prophylactic topical antibiotics. I applaud the retina community for abandoning them. We cataract surgeons are lagging here, as we have good evidence that intraoperative intraocular antibiotics are effective and almost none to support our wide and expensive use of topical antibiotics. I have stopped topical antibiotics in my cataract surgery in favor of an intracameral or intravitreal injection of antibiotic at the time of surgery. In a decade, I predict we cataract surgeons will move away from topical antibiotics as well, saving society and our patients a lot of money and perhaps rendering the antibiotics more effective when we really need them.
In cataract surgery, many of us use medical prophylaxis against intraoperative and postoperative pain, postoperative inflammation and postoperative pressure spikes. These are also interesting topics for the retina surgeon. Is there a role to play in intravitreal injections for topical steroid, NSAID or antihypertensive therapy? As always, there is more to learn, but I found these guidelines interesting and very compatible with our practice patterns in anterior segment surgery.