Prepping techniques, prophylactic antibiotics and surgical technique may all play a part in preventing this most feared cataract surgery complication of them all - post-operative endophthalmitis (POE). Here are five measures and precautions we've instituted in our facility to reduce the risk of POE.
Administer topical pre-op antibiotics. Bacteria on the patient's ocular surface and skin is the most common source of POE. Pre-operative topical antibiotics can reduce this flora. Several days before surgery, your surgeon should start the patient on topical antibiotic drops. Fluoroquinolones are widely used, and the fourth-generation drugs appear to be effective even against strains of resistant bacteria. Some of these drugs, such as gatifloxacin (Zymar) and moxifloxacin (Vigomox) (both 3-4 times a day but every 1-2 hours right after surgery the first day), are capable of penetrating the cornea and achieving significant intraocular concentrations.
To enhance compliance, stress the importance of the drops and the devastation from infection. A recent study found that pre-op topical antibiotics may play a key role in cataract surgery endophthalmitis prophylaxis, particularly in longer, complicated cases involving disruption of the posterior capsule. Researchers conducted a retrospective review of 2,718 extracapsular and phacoemulsification cataract extractions at San Francisco General Hospital between 1984 and 2002. Of these, 1,622 patients (59.7 percent) received three days of pre-op topical antibiotics (Neosporin or sulfacetamide ointment) the remainder did not. All patients were prepped pre-op with povidone-iodine. Three cases (0.27 percent) of post-op bacterial endophthalmitis occurred in the group that didn't receive pre-op antibiotics, with none in the pre-op antibiotic group. Two of the three presented within five days post-op (culture-positive for Streptococcus viridans and Staph. epidermidis), and both involved posterior capsular rupture and anterior vitrectomy. The third was delayed, presenting following a Nd:YAG capsulotomy four months after surgery (culture positive for Corynebacterium sp.).
Continue to use surgical preps. Topical povidone-iodine on the conjunctiva and eyelids has stood the test of time. It's a bactericide as well as active against fungi, protozoa and viruses. It is applied topically at a 5% concentration just before surgery. Let it sit for a couple of minutes before you irrigate and then irritate minimally. Typically, the circulating nurse does this as part of the prep. These preparations gained popularity in the early 1990's, and a recent study comparing them with other types of ocular prepping solutions deemed povidone-iodine the only recommended technique based on current clinical evidence.
Consider surgical incision and technique. Despite the increased risk of POE associated with clear cornea incisions, most surgeons aren't likely to give up this type of incision. However, it may behoove you to have a conversation with your cataract surgeons and share with them what we know about the type of incisions that leak (and increases risk of POE). Incisions that are relatively short in comparison to their width tend to leak. It's easy to miss this, especially if the short area is at one edge of the wound. Inappropriate use of diamond keratomes due to their exquisite sharpness can easily cut out one side of the wound and make it likely to leak. Also some incisions easily pop open due to underlying eye issues (previous corneal transplants, for example) and therefore deserve a suture closure. In sutureless procedures, the surgeon should also be careful to create a strong inner flap closure to prevent microleaks. These can occur at the end of the procedure, so the surgeon usually hydrates the stroma to force the wound shut. But hydration only lasts about 15 minutes; at that point, the integrity of the closure is what protects against microleaks. If there's any concern about wound integrity, the surgeon should place a single interrupted 10-0 nylon suture in the incision.
Watch for leaks. Your staff should be diligent to watch for leaks in the immediate post-operative period, when the wound is at the highest risk for leaks. Patients will report a lot of tearing and the eye collapses or even feels mushy. Delayed microleaks can occur one or more days post-operatively, most likely caused by minute tears in Descemets' membrane at the incision margin (only a trained ophthalmologist can diagnose a Descemets' membrane tear).
Administer post-op antibiotics. These are commonly used to prevent infection, and may be administered subconjunctivally, intracamerally or topically. One study showed a decreased incidence of POE when cefuroxime was given intracamerally at the completion of surgery (although results were not compared with topical or subconjunctival use).
Topical antibiotics are used widely in the United States, although published literature on effectiveness is sparse. Certainly, the fourth-generation fluoroquinolones such as gatifloxacin and moxifloxacin appear to be effective even against resistant strains of bacteria. It's clinically desirable to achieve ocular penetration, and studies show that topical ofloxacin (Ocuflox), levofloxacin (Quixin), gatifloxacin and moxifloxacin achieve an effective concentration in the aqueous humor. However, moxifloxacin has exhibited the highest concentrations. Our center initiates topical fourth-generation fluoroquinolones immediately after surgery, and continues use for about a week (Q2h while awake the day of surgery then 4 times a day).
Rare, but devastating
We've taken these steps in our center, and have noticed a statistically significant decrease in POE - from 1 in 400 to less than 1 in 2,000. The final results will be published at the completion of a seven-year study.