Multi-pronged approach limits endophthalmitis risk

Las Vegas-Although logical arguments can be made to support the use of several strategies for limiting intraocular microbial contamination and minimizing the risk of postoperative endophthalmitis, a need for further, evidence-based research on this subject remains, said Samuel Masket, MD, at the annual meeting of the American Academy of Ophthalmology.

"Part of the answer to the question of 'What should we all do to prevent postoperative infection?' is that we need to act as individuals and members of professional societies to demand that large-scale, well-designed investigations be undertaken," stated Dr. Masket, clinical professor of ophthalmology, University of California at Los Angeles, and in private practice. "Those studies should be designed to determine the clear-cut value of prophylactic methods-particularly intraocular antibiotics-and give direction to both the pharmaceutical manufacturing sector and the FDA."

Discussing existing and potential clinical strategies for preventing postoperative endophthalmitis, Dr. Masket noted a multi-pronged approach is required that:

Decreasing ocular surface microbes involves a chemoprophylactic strategy incorporating povidone-iodine antisepsis and preoperative antibiotic use. In a systematic review of the literature, published by Dr. Masket and colleagues in 2002 [Ciulla TA, Starr MB, Masket, S. Ophthalmology. 2002;109:13-24], no prophylactic technique met tier I literature criteria to be considered crucial to clinical outcome, and only preoperative povidone-iodine had sufficient literature evidence to support a strong clinical recommendation.

Dr. Masket noted that a symbiosis exists between povidone-iodine and antibiotics for short- and long-term efficacy, and that fourth-generation fluoroquinolones currently are considered the antibiotics of choice for surgical prophylaxis. Appropriate use, however, requires knowledge of the pharmacokinetics and pharmacodynamics of the selected agent.

"The fourth-generation fluoroquinolone moxifloxacin (Vigamox, Alcon Laboratories) has potent activity against common endophthalmitis pathogens, but kill curve studies show that topical application should begin 2 hours in advance of surgery to approach bacterial eradication," Dr. Masket said.

Intraoperative risks

Preventing intraoperative bacterial contamination in the eye involves methods to limit pathways for microbial entry. In that regard, it is critical that draping isolate the lids and lashes, and pooling of fluids on the ocular surface should be prevented. Avoiding complications is critical as well, based on evidence showing that, for example, capsular rupture increases the risk of infection by 4- to 5-fold.

For preventing contamination of the anterior chamber postoperatively, hermetic sealing of the incision is the absolute key, Dr. Masket said.

Optimizing incision integrity involves avoiding tissue distortion, he continued. Dr. Masket also advocated stromal hydration, elevating the IOP to close the internal aspect of the valve, and then lowering it to physiologic levels before checking the competency of the closure with a Seidel test.

"I check IOP with a tonometer in all cases and will suture as needed. We can all look forward to the development of tissue glues in the future as a new method for incision sealing," he said.

Dr. Masket also mentioned that he conducted a study demonstrating that ocular hypotony from wound leakage was not necessarily the rule early after clear corneal incision surgery. In that investigation, 50 eyes underwent phacoemulsification through a 2.2-mm clear corneal incision. IOP was reestablished at physiologic levels at the end of the procedure, and all incisions were Seidel negative. IOP measured at 2 to 6 hours postoperatively ranged from 11 to 35 mm Hg with a mean of 19.2 mm Hg.

"We had no cases of hypotony or wound leak, Dr. Masket said. "When managed appropriately, the clear corneal incision should not lead to an increased rate of infection."