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To reduce the risk of endophthalmitis after cataract surgery a multimodal approach is needed. Assuring a water-tight wound closure without the use of stromal hydration and use of a fourth-generation fluoroquinolone are two important factors. An analysis of data from patients undergoing clear corneal cataract extraction at the University of Texas Southwestern Medical Center supports these recommendations.
Chicago-Endophthalmitis should be a rare occurrence if surgeons adhere to good surgical technique that includes maintenance of a sterile environment, antisepsis of the lids and ocular surface, thoughtful prophylactic antibiotic use, and most importantly, assuring water-tight wound closure without stromal hydration, said James P. McCulley, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.
"In the interest of saving a few seconds and a few dollars, cataract surgeons will perform stromal hydration and skip suturing the wound," said Dr. McCulley, professor chairman, Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas. "However, the effect of stromal hydration lasts only a few minutes, so it is critical to make sure that the incision, with or without a suture, is water-tight without stromal hydration."
As evidence for that premise, Dr. McCulley reported that at his own institution, only a single case of endophthalmitis occurred in 11,928 cataract procedures performed through a temporal clear corneal incision. That translates into a rate of 0.08 per 1,000, which is superior to the rate associated with intracameral cefuroxime use in the European Society of Cataract and Refractive Surgeons (ESCRS) study of post-cataract surgery endophthalmitis prophylaxis. It also is much lower than the rate of 38 per 1,000 cases reported in the control group of that prospective, randomized trial, in which no intracameral cefuroxime or preoperative levofloxacin was used.
"The ESCRS study also found an increased risk of endophthalmitis associated with use of a clear corneal incision," Dr. McCulley said. "My best guess is that not having a water-tight wound closure at the end of surgery was a major factor for that and the high rate of endophthalmitis in the ESCRS control group."
Dr. McCulley also addressed the issue of antibiotic selection. He said that in the prospective ESCRS study, groups that did not receive intracameral cefuroxime had a nearly six-fold higher rate of endophthalmitis compared with patients who received intracameral cefuroxime. Dr. McCulley commended the ESCRS study as a major undertaking and recognized that it provided a large amount of experience with use of intracameral cefuroxime. Nevertheless, he observed that intracameral cefuroxime has not gained wide acceptance in the United States.
"There is no commercially available cefuroxime for ophthalmic use in this country, but we do have fourth-generation fluoroquinolones," Dr. McCulley said.
Comparing the pharmacodynamics of cefuroxime and the fourth-generation fluoroquinolones, he noted cefuroxime has time-dependent killing activity, whereas fluoroquinolones are concentration-dependent killers, which makes them more ideal for eradicating any bacteria that enter the eye during or after surgery. Furthermore, cefuroxime is a second-generation beta-lactam to which some potential endophthalmitis pathogens are resistant.
Compared with levofloxacin, which was used as the topical fluoroquinolone in the ESCRS study, the fourth-generation fluoroquinolones have superior potency and penetration.
"In a study we conducted that evaluated q.i.d. antibiotic dosing regimens that would typically be used postoperatively, moxifloxacin levels achieved in the aqueous humor exceeded the MPC concentration for all susceptible endophthalmitis pathogens, which assures rapid killing, and gatifloxacin reached levels exceeding the MIC," Dr. McCulley said.