Bacterial contamination of the anterior chamber during phacoemulsification cataract surgery

PURPOSE: To determine the incidence of bacterial contamination of the anterior chamber after phacoemulsification cataract surgery with intraocular lens (IOL) implantation. SETTING: Department of Ophthalmology, Royal Prince Alfred Hospital, Sydney, Australia. METHODS: Ninety-eight consecutive eyes of 96 patients having phacoemulsification cataract surgery with IOL implantation were included in this prospective study. Two intraoperative anterior chamber aspirates were obtained from each patient, 1 taken at the start and the other at the conclusion of surgery. In addition, preoperative and postoperative conjunctival swabs were acquired. The 4 specimens were cultured using direct culturing techniques under aerobic and anaerobic conditions for 14 days. No preoperative antibiotics were used. RESULTS: The incidence of intraoperative anterior chamber contamination was 0% (95% confidence interval, 0%-3.7%) as all intraoperative anterior chamber samples proved culture negative. Sixty-five percent of the preoperative conjunctival swabs were positive for growth, with corynebacteria, coagulase-negative staphylococci, and Propionibacterium acnes being the most frequently cultured organisms. Sixteen percent of the postoperative conjunctival swabs were positive for growth, with corynebacteria and coagulase-negative staphylococci being the most common bacteria. One patient developed culture-positive postoperative endophthalmitis; using pulsed-field gel electrophoresis for further typing, the implicated Staphylococcus epidermidis was indistinguishable from that isolated from the patient's preoperative conjunctival swab. CONCLUSIONS: The bacterial contamination rate of the anterior chamber after phacoemulsification and IOL implantation was extremely low. Additional findings support the conjunctiva as being a primary source of bacteria causing postoperative endophthalmitis as well as the ability of povidone-iodine to reduce the conjunctival bacterial load.     

Heparin and heparin-surface-modification reduce Staphylococcus epidermidis adhesion to intraocular lenses

Bacterial adherence to intraocular lenses (IOLs) could be the cause of endophthalmitis following cataract surgery and lens implantation. The majority of cases of postoperative endophthalmitis are caused by microflora that reside on or near the eye of the patient. Staphylococcus epidermidis commonly colonizes the eyelid margin and conjunctiva and is the most common organism causing postoperative endophthalmitis. In this study, the in vitro adherence of S. epidermidis to regular poly-methyl methacrylate (PMMA) IOLs and to heparin-surface-modified (HSM) PMMA IOLs was investigated. The effects of heparin and antibiotics in solution on the adherence of bacteria to regular PMMA IOLs were evaluated. Adhesion of bacterial cells to IOLs was determined by counting the viable cells attached to the lenses. Significantly, fewer S. epidermidis attached to HSM-PMMA IOLs and to regular PMMA IOLs treated with heparin than to PMMA IOLs (p < 0.001). Furthermore, bacteria attached in significantly lower numbers to regular PMMA IOLs treated with heparin than to HSM-PMMA IOLs (p = 0.0031). Antibiotics in solution had no significant effect on bacterial adherence to PMMA IOLs. These data indicate that the use of HSM-PMMA IOLs and treatment of PMMA IOLs with heparin could diminish the incidence of postoperative endophthalmitis and intraocular inflammation associated with IOL implantation. This revised version was published online in September 2006 with corrections to the Cover Date.     

Risk of endophthalmitis after cataract surgery using different protocols for povidone- iodine preoperative disinfection.

AIMS: The aim of this study was to assess the risk of postoperative endophthalmitis associated with different prophylactic protocols, using povidone-iodine disinfection of the skin and conjunctiva in patients undergoing cataract surgery over an 8-year period at Chang Gung Memorial Hospital (Kaohsiung, Taiwan). METHOD: This was a retrospective, comparative, case-controlled study. Data were collected on patients who received different prophylactic disinfection protocols prior to extracapsular cataract extraction with intraocular lens implantation between January 1992 and January 2000. Possible risk factors for the occurrence of postoperative endophthalmitis were analyzed. RESULTS: Medical charts for a total of 10,614 extracapsular cataract extraction surgeries performed during the 8-year period were reviewed, and 12 eyes that developed postoperative endophthalmitis were identified and analyzed. Another 120 eyes matched for age and gender of the patient were randomly selected as controls. Skin preparation with 5% povidone-iodine was associated with an increased risk of postoperative infection, compared to that of 10% povidoneiodine. On the conjunctiva, a lack of 5% povidone-iodine disinfection was associated with an increased risk of postoperative infection, compared to 5% povidone-iodine disinfection. CONCLUSIONS: Preoperative skin disinfection with 10% povidone-iodine and conjunctival disinfection with 5% povidone-iodine significantly reduced the relative risk of postoperative endophthalmitis.     

Bacterial contamination of anterior chamber during IOL surgery

PURPOSE: To study the nature and frequency of bacterial contamination during cataract surgery. METHODS: The preoperative smears from the conjunctiva and anterior chamber (AC) fluid aspirates during extra-capsular cataract surgery (ECCE) with posterior chamber intraocular lens (PCIOL) implantation in 40 eyes were analysed for aerobic and anaerobic bacteria. Any change in the bacterial strains isolated before and after cataract surgery was also studied. RESULTS: AC fluid aspirates were positive for bacteria in 15 eyes (37.5%). Coagulase-negative Staphylococcus was the most common aerobe (39.4%) and Propionibacterium acnes the most common anaerobe. Of the 15 cases with positive AC fluid cultures, 6 showed an organism in the AC aspirate different from the conjunctival smear. CONCLUSION: Clinically there was no endophthalmitis in any of the eyes. Factors such as preoperative antibiotic use, the antibacterial properties of aqueous, or low inoculum size could explain this. The preoperative conjunctival smear may not be useful in predicting the AC fluid contamination or outcome of cataract surgery.     

不同材料人工晶状体表面表皮葡萄球菌黏附实验的研究

背景感染性眼内炎是白内障摘出及人工晶状体（IOL）植入术后最严重的并发症之一，细菌黏附于IOL表面随手术带人眼内是其主要原因，了解细菌对IOL的黏附情况对预防术后眼内炎的发生具有重要意义。目的研究不同材料的IOL光学表面表皮葡萄球菌的黏附情况，比较细菌培养菌落计数及扫描电子显微镜计数2种方法的优缺点。方法疏水性丙烯酸酯IOL、聚甲基丙烯酸甲酯IOL（PMMAIOL）、肝素修饰聚甲基丙烯酸甲酯（HSM—PMMAIOL）、硅凝胶IOL（SIIOL）、亲水性丙烯酸酯IOL5种不同材料的IOL（每种6枚）置于表皮葡萄球菌（ATCC12228）细菌悬液1h后，采用细菌培养菌落计数及扫描电子显微镜2种方法观察表皮葡萄球菌在各种IOL表面的黏附数量。结果细菌培养菌落计数发现疏水性丙烯酸酯IOL和PMMAIOL最易于黏附细菌，亲水性丙烯酸酯和HSM—PMMAIOL黏附的细菌最少，5种IOL中细菌黏附数的比较差异有统计学意义（F=100．084，P=0．000），亲水性丙烯酸组和HSM—PMMA组间差异无统计学意义（t=2．285，P=0．052）；扫描电子显微镜观察结果显示5种IOL组细菌在IOL上光学分布表面计数的总体比较差异有统计学意义，按照细菌在IOL上黏附的数量从多到少依次为Hydrophobie〉PMMA〉SI〉Hvdrophilic〉HSM—PMMA（F：118．065，P=0．000）。两种细菌菌落计数方法比较发现扫描电子显微镜法优于细菌培养菌落计数法，差异有统计学意义（t=5．019，P=0．000）。结论5种IOL中以亲水性丙烯酸酯和HSM～PMMAIOL黏附的细菌最少，提示亲水性丙烯酸酯IOL和HSM—PMMAIOL在降低白内障IOL植入术后眼内炎的发生方面有一定的作用。     

Intraocular lens implants and risk of endophthalmitis

AIM—To investigate the possible association between the use of three piece foldable silicone polypropylene (SPP) intraocular lenses (IOLs) and an increased risk of postoperative endophthalmitis.
METHODS—A retrospective analysis was conducted of all cases of postoperative endophthalmitis following phacoemulsification surgery in a single unit over a 3 year period. The incidence of postoperative endophthalmitis in eyes with SPP IOLs was compared with the incidence in eyes with single piece polymethylmethacrylate (PMMA) IOLs.
RESULTS—772 cataract extractions by phacoemulsification were performed. One (0.16%) of the 622 patients with PMMA IOLs developed endophthalmitis. Excluding one patient who had aplastic anaemia, five (3.33%) of 150 patients with SPP IOLs developed endophthalmitis. The relative risk for postoperative endophthalmitis associated with the use of the SPP IOL compared with the PMMA IOL was 20.1 (p=0.015).
CONCLUSION—This study adds further evidence to the concept that SPP IOLs can be a significant risk factor in the development of postoperative endophthamitis.

Keywords: cataract surgery; phacoemulsification; intraocular lenses; endophthalmitis     

Bacterial contamination in the anterior chamber after povidone-iodine application and the effect of the lens implantation device

PURPOSE: To assess the incidence of anterior chamber bacterial contamination during cataract surgery, and compare results of injector implantation and forceps implantation of foldable intraocular lenses (IOLs). SETTING: Department of Ophthalmology and Institute of Medical Microbiology, Semmelweis University, Budapest, Hungary. METHODS: This prospective randomized controlled clinical study comprised 97 eyes of 96 patients. Antibiotic eyedrops were not used; however, povidone-iodine 10% solution was used to prepare the eyebrow and eyelids and povidone-iodine 5% to disinfect the ocular surface. A Steri-Drape (3M) was used to surround the eye. Aqueous fluid samples were aspirated from the anterior chamber at the beginning and the end of surgery. The samples were cultured for 14 days under aerobic and anaerobic conditions simultaneously. Cataract surgery was performed using a sutureless, superotemporal, clear corneal phacoemulsification technique. The IOL was implanted with an injector (n = 47) or a forceps (n = 50), with the instrument randomly selected. The frequency of positive bacterial cultures with each implantation method was compared using the Fisher exact test. RESULTS: Bacteria were found in the conjunctival samples in 21 eyes (21.65%) before povidone-iodine application and in 4 eyes (4.12%) after disinfection. The anterior chamber sample before surgery was culture positive for Staphylococcus epidermidis in 2 eyes and for Micrococcus luteus in 1 eye. After surgery, the culture was positive for S epidermidis in 1 eye (2.15%) in the injector group and 1 eye (2.00%) in the forceps group (P = .74). Neither sample came from an eye that had a positive culture preoperatively. There were no intraoperative complications. CONCLUSIONS: In uneventful clear corneal phacoemulsification, meticulous technique can prevent antibiotic use during surgery. No difference in anterior chamber bacterial contamination was found between IOL implantation using an injector or a forceps.     

Bacterial contamination: epidemiology in cataract surgery

PURPOSE: To evaluate anterior chamber (AC) bacterial contamination at the end of cataract surgery in a large series of patients, to determine the influence of operative technique on ocular contamination. METHODS: Retrospective study of 2,624 patients undergoing cataract extraction, 354 extracapsular cataract extraction (ECCE) and 2,270 phacoemulsification. Anterior chamber aspirates were performed on completion of surgery for microbiological studies. RESULTS: One hundred and thirty two patients (5%) had culture-positive anterior chamber aspirates. Coagulase-negative Staphylococcus, Propionibacterium sp. and Corynebacterium sp. were the most commonly isolated organisms. The AC contamination rates during ECCE (5.6%) and phacoemulsification (4.7%) were not statistically different. There was a statistically significantly higher risk of AC contamination in eyes receiving an intraocular lens (IOL) with polypropylene haptics (9.9%) than in eyes receiving the same IOL with polymethylmethacrylate haptics (4.4%). CONCLUSION: Surgical technique had no statistically significant effect on ocular contamination. Polypropylene haptics IOLs were associated with a higher risk of bacterial contamination.     

Explantation of silicone plate haptic intraocular lenses

The stress on small self-sealing incisions in cataract surgery has resulted in the increased use of foldable intraocular lenses (IOL). Plate haptic silicone IOLs implanted with the help of an injector require extremely small incision lengths and are extensively used. The authors discuss difficulties in explanting such lenses, especially in inflamed eyes. Two patients who underwent plate-haptic silicone IOL explantation for postoperative bacterial endophthalmitis are described. Plate haptic IOLs have a tendency to dislocate posteriorly because of poor capsular fixation and increased posterior bowing. Enlarging a small rhexis prior to attempting explantation of these lenses reduces this complication. Difficulties inherent in explanting plate haptic silicone IOLs in inflamed eyes are discussed, along with suggestions to overcome them.     

Influence of intraocular lens material on the development of acute endophthalmitis after cataract surgery?

PURPOSE: To investigate the causal relationship between acute postoperative endophthalmitis (POE) after cataract surgery and the biomaterial properties of the intraocular lens (IOLs) implanted. METHODS: This retrospective cohort study included all patients who had undergone cataract surgery with IOL implantation at the Lyon Croix-Rousse University Hospital between 1st January 1994 and 31st December 2004. Details respecting the type of IOL implanted (material and manufacturer) were meticulously recorded. The number of patients presenting with POE within 6 weeks of cataract surgery was documented together with their medical characteristics. These data were then compared, and Fisher's exact test was used to establish the significance of any apparent associations. RESULTS: Eight of the 5837 eyes manifested acute POE (0.14%). Seven of these were composed of polymethylmethacrylate (PMMA) and one of heparinized PMMA. Patients with PMMA IOLs carried a higher risk of developing POE than did those implanted with either heparinized PMMA (P=0.001), hydrophilic acrylic, or hydrophobic acrylic IOLs (P=0.002). CONCLUSIONS: The incidence of acute POE after cataract surgery in our hospital is similar to that currently reported for other institutions in developed countries. Our results add further evidence that IOL material and type are factors contributing to the risk to develop an acute POE after cataract surgery, and that PMMA IOLs may be associated with an increased risk of POE.