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New benchmark in preventing phacoemulsification-related endophthalmitis Matthew C. Carnahan, MD, MS, William J. Chang, MD, Neal H. Shorstein, MD, Lisa J. Herrinton, PhD During 2010 and 2011, we reported a rate of endophthalmitis of 0.14 per 1000 in the Diablo Service Area of Kaiser Permanente; this low rate corresponded to adoption of intracameral injections at the end of cataract surgery among all patients treated in that medical center.1 In recent years and in response to mounting evidence of the effectiveness and safety of intracameral injections of antibiotic in preventing cataract surgery–related endophthalmitis,2 our network of surgeons across the entire Northern California region of Kaiser Permanente (including the Diablo Service Area and 15 other service areas) has increased adoption of intracameral antibiotics at the end of cataract surgery. Some surgeons currently prefer cefuroxime as a first-line drug; others use moxifloxacin. In cases of allergy, a small percentage of patients receive vancomycin.3 Following publication of our 2010–2011 experience and as part of our mission to provide high-quality care to our patients, we took steps to increase implementation of intracameral injections systemwide. From January 1 to December 31, 2013, an increasing proportion of our cataract surgery patients received intracameral antibiotics, with an average proportion of 79% for the calendar year, similar to the proportion reported in Europe.4 Using the same case definition that we used in our previous report, we calculated the rate of endophthalmitis for the calendar year 2013 in the entire Northern California region. Among 32 562 routine phacoemulsification procedures, we observed 3 cases of endophthalmitis. One of these occurred among 6891 procedures performed without intracameral injections (rate 0.14 per 1000; 95% confidence interval [CI], 0.00-0.80 per 1000); the pathogen was methicillinresistant Staphylococcus aureus. The 2 other cases occurred among 25 671 procedures with intracameral injections (rate 0.08 per 1000; 95% CI, 0.00-0.28 per 1000). One case that received intracameral moxifloxacin occurred the day after surgery; the etiology was coagulase-negative Staphylococcus species. The second case, which received intracameral cefuroxime, involved Enterococcus faecalis endophthalmitis following removal of sutures 30 days after uneventful cataract surgery. This resulted in a Seidel-positive wound; a contact lens was placed and ofloxacin drops were prescribed 2 days prior to clinical signs of infection. Arguably, this second case would not have been affected by 1568

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perioperative antibiotic prophylaxis and could be reasonably excluded from expected prophylactic action, yielding 1 case of clinical endophthalmitis for a rate of 0.04 per 1000 (95% CI, 0.00-0.22). We are currently analyzing these and earlier data for a research study funded by the United States National Eye Institute (R21 EY022989) to further clarify the role of intracameral and topical agents in preventing endophthalmitis following cataract surgery. As part of that work, we have observed a modest trend of decreasing endophthalmitis risk of about 6% per year, above and beyond the effect of intracameral injection, which could have resulted from better wound construction and maintenance (eg, stromal hydration and higher eye pressure at the conclusion of surgery) as well as other improvements that we have not measured. The results of this study will be available in a matter of months. In the meantime, and although uncontrolled, the endophthalmitis rate we observed for 2013 provides further evidence in support of intracameral delivery for antibiotic prophylaxis5 together with a new benchmark for surgical safety in cataract surgery. REFERENCES 1. Shorstein NH, Winthrop KL, Herrinton LJ. Decreased postoperative endophthalmitis rate following institution of intracameral antibiotics in a Northern California eye department. J Cataract Refract Surg 2013; 39:8–14 2. ESCRS Endophthalmitis Study Group. Prophylaxis of postoperative endophthalmitis following cataract surgery: results of the ESCRS multicenter study and identification of risk factors. J Cataract Refract Surg 2007; 33:978–988 3. Nguyen ET, Shorstein NH. Preparation of intracameral antibiotics for injection. J Cataract Refract Surg 2013; 39:1778–1779 4. Barry P. Adoption of intracameral antibiotic prophylaxis of endophthalmitis following cataract surgery; update on the ESCRS Endophthalmitis Study. J Cataract Refract Surg 2014; 40:138–142 s L, Gardner S. ESCRS Guidelines for Preven5. Barry P, Cordove tion and Treatment of Endophthalmitis Following Cataract Surgery: Data, Dilemmas and Conclusions. Dublin, Ireland, European Society of Cataract and Refractive Surgeons, 2013; Available at: http://www.escrs.org/downloads/EndophthalmitisGuidelines.pdf. Accessed May 1, 2014

Simple method to restore a fractured 10-0 polypropylene suture using a single fisherman’s knot Min Ho Kang, MD, PhD, Mincheol Seong, MD, PhD, Han Woong Lim, MD, Hee Yoon Cho, MD, PhD When a patient's eye has inadequate capsule support for posterior chamber implantation in the capsular bag or ciliary sulcus, there are 2 options: open-loop 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.07.011

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anterior chamber, scleral-sutured posterior chamber, or iris-sutured posterior chamber intraocular lens (PC IOL) implantation or fibrin glue–assisted sutureless PC IOL implantation.1,2 In scleral-sutured PC IOL implantation, a 10-0 polypropylene suture attached to a standard needle is tied to the haptic of the IOL and sclera.3,4 As a suture material, polypropylene is strong, durable, and nonabsorbent, but the 10-0 polypropylene suture is very thin so it is easily fractured and spontaneous 10-0 polypropylene suture breakage can occur.4,5 Even after insertion of the IOL, the 10-0 polypropylene suture can be fractured accidentally by inadvertent handling of surgical instruments. Fracture of the 10-0 polypropylene suture can be embarrassing to trainee and experienced surgeons. Tying the suture to the haptic a second time can injure the corneal endothelium, iris, and ciliary body and may also take more operating time. The fisherman's knot joins 2 lines with a symmetrical structure consisting of 2 overhand knots, each tied around the standing part of the other.6 We tested the clinical usefulness and knot security of a 10-0 polypropylene suture restored with a single fisherman's knot. MATERIALS AND METHODS Polypropylene 10-0 (Prolene, Ethicon, Inc.) sutures were removed from their packages and fixed intact into the paper frame to load into a materials testing machine (Instron 5966 load frame, model 2701-065 controller, Instron Corp.) for tensile strength. A single fisherman's knot was made under the surgical microscope and instruments. The 10-0 polypropylene suture was cut and the ends of lines to be joined were overlapped. The end of the right line was wrapped around the left line once into the loop, and the tag end was tightened. This was repeated with the end of the line on the right, making the same knot and the standing lines

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were pulled in the opposite direction to slide the 2 knots together. The ends of the knots were then clipped (Figure 1). The measured length was 2.5 cm, and the universal testing instrument continuously measured load while each end of the 10-0 polypropylene suture was subjected to tensile forces until failure occurred. Failure was defined as breakage of the suture or complete knot slippage. To compare the knot security with suture material, t tests were performed with SPSS software 17.0 with significance at less than or equal to 0.05. The clinical model was tested using sclera in which partial- and full-thickness sutures were made by the 10-0 polypropylene suture restored with a single fisherman's knot.

RESULTS The mean tensile strength of 10-0 polypropylene and 10-0 polypropylene with a single fisherman's knot were 0.47N G 0.02 (SD) and 0.27 G 0.05 N, respectively (PZ.02). All 10-0 polypropylene sutures with a single fisherman's knot came untied at the knot and without a fracture when failure occurred. The 10-0 polypropylene suture with a single fisherman's knot had approximately 57% the mean tensile strength of the intact suture. The scleral model demonstrated that there was no fracture or knot slippage when the suture was passed through partial- and full-thickness sclera (Figure 2). DISCUSSION Restoring fractured 10-0 polypropylene sutures using a knot may not convince the surgeons of knot security and the coefficient of friction. The knot is generally known as the weakest link in any knotted suture loop, regardless of the knot configuration and the kind of suture material used.7 The surgeons may prefer to use the intact 10-0 polypropylene suture rather than the fractured 10-0 polypropylene suture.

Figure 1. Creation of the single fisherman's knot. A: Overlap the ends of lines to be joined. B: Take the end of the right line and wrap it once around the left line into the loop, then pull the tag end to tighten. C and D: Repeat with the end of the left line, making the same pattern. E: Pull the standing lines in opposite directions to slide the 2 knots together. F: Clip the ends near the knot.

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Figure 2. Clinical effectiveness of a single fisherman's knot using a scleral model. There was no fracture or knot slippage during multiple passes through the sclera (arrows: partial- and full-thickness sclera sutures; arrowheads: single fisherman's knot).

A suture that is knotted has approximately onethird the tensile strength of the same material unknotted.8 In our test, the single fisherman's knot had 57% of the tensile strength of the intact suture. Thus, the single fisherman's knot has effective tensile strength; it has the knot security to pass through sclera and also has a low coefficient of friction. It could be a good option if the 10-0 polypropylene suture accidentally broke after successful insertion of an IOL for transscleral suture fixation. In our clinical case, we made a single fisherman's knot with the 2 ends of the suture and completed the Z-suture without knot fracture or slippage. The single fisherman's knot has sufficient knot security and it can also be used in various surgical situations because of its simplicity. Furthermore, we should consider the 9-0 polypropylene suture for increasing the long-term security of a scleral-sutured IOL in view of spontaneous 10-0 polypropylene suture breakage.

REFERENCES 1. Wagoner MD, Cox TA, Ariyasu RG, Jacobs DS, Karp CL. Intraocular lens implantation in the absence of capsular support; a report by the American Academy of Ophthalmology (Ophthalmic Technology Assessment). Ophthalmology 2003; 110:840–859 2. Agarwal A, Kumar DA, Jacob S, Baid C, Agarwal A, Srinivasan S. Fibrin glue–assisted sutureless posterior chamber intraocular lens implantation in eyes with deficient posterior capsules. J Cataract Refract Surg 2008; 34:1433–1438 3. Smiddy WE, Sawusch MR, O’Brien TP, Scott DR, Huang SS. Implantation of scleral-fixated posterior chamber intraocular lenses. J Cataract Refract Surg 1990; 16:691–696 4. Buckley EG. Safety of transscleral-sutured intraocular lenses in children. J AAPOS 2008; 12:431–439 5. Price MO, Price FW Jr, Werner L, Berlie C, Mamalis N. Late dislocation of scleral-sutured posterior chamber intraocular lenses. J Cataract Refract Surg 2005; 31:1320–1326 6. Turner JC, van de Griend P. History and Science of Knots (Series on Knots and Everything vol. 11). Singapore, World Scientific, 1996 7. Rodeheaver GT, Thacker JG, Edlich RF. Mechanical performance of polyglycolic acid and polyglactin 910 synthetic absorbable sutures. Surg Gynecol Obstet 1981; 153:835–841 8. Herrmann JB. Tensile strength and knot security of surgical suture materials. Am Surg 1971; 37:209–217

J CATARACT REFRACT SURG - VOL 40, SEPTEMBER 2014

Simple method to restore a fractured 10-0 polypropylene suture using a single fisherman's knot.

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