Prophylaxis of postoperative endophthalmitis

Abstract

We commend the authors of the European Society of Cataract & Refractive Surgeons' (ESCRS) study of the prophylaxis of postoperative endophthalmitis after cataract surgery1,2 for their comprehensive and thorough work in addressing this vital topic. The main findings of the study—ie, that intracameral cefuroxime has an intrinsic benefit and that intracameral cefuroxime plus postoperative topical levofloxacin is a more effective prophylaxis than either agent in isolation—are welcome, if not unexpected. It is therefore beneficial to administer cefuroxime at the end of phacoemulsification procedures. What this study does not address, however, is how to administer it. Despite the study's maximum antibiotic regimen, cases of endophthalmitis were seen. Therefore, we must continue to look for ways to reduce the incidence. At our ophthalmic department, patients having cataract surgery receive 3 drops of topical chloramphenicol 0.5% preoperatively, povidone–iodine in the conjunctival sac just before surgery, subconjunctival cefuroxime (125 mg) at the end of surgery, and a tapered course of combination betamethasone–neomycin eyedrops for 3 weeks postoperatively. At our hospital, in a consecutive series of 5641 eyes from January 1, 2000, to December 31, 2005, there was only 1 case (culture negative) of presumed postoperative endophthalmitis, which occurred after surgery complicated by posterior capsule rupture and anterior vitrectomy. This yields an incidence of postoperative endophthalmitis of 0.018% (zero cases of culture-positive endophthalmitis) compared with the incidence of 0.058% (2/3428) in the ESCRS study. Our experience suggests that cefuroxime may provide more effective prophylaxis when administered into the subconjunctival space than when administered into the anterior chamber. The reason for this benefit is not clear. Subconjunctival administration may offer better prophylaxis by behaving as a depot preparation and prolonging the availability of the antibiotic via sustained absorption through the ocular coats. The increased duration of this bacteriolytic environment would impede the establishment of pathogens during the crucial early wound-healing period. When subconjunctival administration is combined with preoperative and postoperative antibiotics, the eye is further protected during the most vulnerable period. An environment hostile to bacterial survival would be particularly beneficial during the first 24 hours while the corneal epithelium is healing.3 Animal studies4 show that antibiotics given subconjunctivally can be detected in the anterior chamber 24 hours later, suggesting that this method would provide the desired antibacterial cover until the natural barrier functions were restored. The ESCRS study shows intracameral antibiotic to be better than no antibiotic but does not look at different modes of administration. Our series suggests that subconjunctival cefuroxime may be a more effective prophylaxis against postoperative endophthalmitis. Intracameral cefuroxime is not a panacea, and the choice and delivery route of postoperative antibiotic constitute only part of the prevention of postoperative endophthalmitis. Factors such as careful preoperative assessment, meticulous preparation and draping of the surgical field, and guaranteed sterility of equipment are no less important. Further prospective studies are needed to find the most effective route of administration and type of antibiotic in the quest to further reduce the rate of this serious intraocular surgery complication.