Anterior chamber aspirate cultures in small incision cataract surgery

Purifying the Air over the Operating Field and Reducing the Possibility of Airborne Contamination with a New Mobile Laminar Airflow Device

PURPOSE

To investigate the effectiveness of a mobile laminar airflow (LAF) device designed to reduce both airborne particles and lint fibers within the sterile field during cataract surgery.

SETTING

Cincinnati Eye Institute, Cincinnati, Ohio, USA.

DESIGN

Prospective case series.

METHODS

The number of airborne particles sized 0.5, 1.0 and 1.5 microns were measured at different locations and times during 116 routine phacoemulsification procedures with and without the use of a mobile LAF device. In a companion study, the presence of lint fibers in 99 eyes undergoing cataract surgery with a mobile LAF device was compared to 50 eyes in the control group. Lint fibers were differentiated as either falling onto the ocular surface or being carried into the sterile field by an instrument.

RESULTS

A statistically significant reduction (p<0.0005) occurred in all three particle sizes measurements when the LAF device was used: 79.0%, 81.7% and 90.8% in the 0.5, 1.0 and 5.0 micron particles, respectively. Lint fibers were identified in 18% of eyes in the control group and 16.16% of eyes in the LAF group. Although the number of lint fibers carried into the sterile field was similar in each group, the incidence of lint fibers falling onto the sterile field was reduced from 6% to 0% when the LAF was used (p=0.014).

CONCLUSION

The mobile LAF device is highly effective in reducing the number of particulate matter and lint fibers within the sterile surgical field when used during cataract surgery.

The Effect of Intraoperative Antibiotics in Irrigating Solutions on Aqueous Humor Contamination and Endophthalmitis after Phacoemulsification Surgery

PURPOSE

To determine the efficacy of intraoperative antibiotic use in irrigating solutions on aqueous humor contamination during phacoemulsification surgery and to evaluate the corresponding risk of postoperative endophthalmitis.

METHODS

644 eyes of 640 patients who underwent phacoemulsification surgery with foldable intraocular lens (IOL) implantation were included in this study. Preoperative conjunctival smears were taken and eyes were allocated to receive irrigating infusion fluid containing either balanced salt solution (BSS)-only (group 1; 322 eyes) or BSS with antibiotics (vancomycin and gentamycin) during surgery (group 2; 322 eyes). Bacterial contamination rates of aqueous humor samples taken in the beginning and at the end of operation were compared. Predictive factors for the development of postoperative endophthalmitis were determined by clinical and microbiologic analyses.

RESULTS

The rates of culture-positivity were similar between group 1 and group 2 for both preoperative conjunctival smears and aqueous samples (p > 0.05). Aqueous samples taken at the end of operation were found to be contaminated in 68 (21.1%) eyes in group 1 and 22 (6.8%) eyes in group 2, and the difference was significant (p = 0.0001; OR = 3.65 (2.1-6.0)). Capsular rupture was associated with higher rate of contamination in both groups (p = 0.0001; OR = 7.7 and p = 0.0001; OR = 8.1). Two eyes in the BSS-only group developed postoperative endophthalmitis and these cases had posterior capsular rupture during the surgery and culture-positivity for staphylococcus epidermidis throughout the study.

CONCLUSIONS

Intraoperative antibiotic irrigation decreases aqueous humor contamination during phacoemulsification. Further studies are warranted to determine the interrelationship between aqueous humor contamination and endophthalmitis in eyes with posterior capsular rupture.

Evaluation of a new method of irrigation and aspiration for removal of ophthalmic viscoelastic device during cataract surgery in a porcine model

BACKGROUND

To determine if a method for irrigation and aspiration (I/A) during cataract surgery provides effective removal of ophthalmic viscoelastic device (OVD).

METHODS

Japanese porcine eyes were used to evaluate I/A performance with Technique 1 (the I/A tip placed on the center of the anterior surface of the IOL), Technique 2 (the I/A tip alternately pressed near the edge of the IOL optic anterior surface on one side and then the other to tilt the IOL back and forth), and Technique 3 (the I/A tip inserted behind the IOL optic, between it and the posterior capsule). Techniques 1 and 2 were compared using the Miyake-Apple posterior view video technique to visualize the flow of irrigation fluid containing triamcinolone acetonide particles behind the IOL. To check the efficacy of OVD removal from behind the IOL for of all three I/A techniques, OVD with fluorescein beads were inserted inside the lens capsule before implantation of the IOL. After each I/A technique, eyes were prepared for Miyake-Apple viewing and pictures of the lens capsule were taken using fluorescent microscopy. Residual fluorescein beads in the capsular bag were analyzed.

RESULTS

Technique 1 resulted in a straight flow of fluid behind the IOL, while Technique 2 resulted in a vortex flow. The average amount of OVD retained inside the capsule after using Technique 2 or 3 was significantly lower than after using Technique 1 (p <0.0001).

CONCLUSIONS

Technique 2 proved to remove more effectively fluorescein bead-labelled OVD under the IOL than Technique 1.

Ocular penetration and efficacy of levofloxacin using different drug-delivery techniques for the prevention of endophthalmitis in rabbit eyes with posterior capsule rupture

PURPOSE

To evaluate the effects of different drug-delivery techniques for levofloxacin (LVFX) in ocular penetration and the prevention of endophthalmitis using an aphakic rabbit model with posterior capsule rupture (PCR).

METHODS

LVFX was administered to aphakic rabbit eyes with or without PCR using eye drops (EDs), subconjunctival injection (SCI), or intracameral (IC) injection. The concentration of the drug in the vitreous and aqueous humors was estimated at 2 h after injection. In another study, aphakic rabbit eyes with PCR were inoculated with Enterococcus faecalis, immediately followed by 0.5% LVFX ED, 0.5% moxifloxacin (MFLX) ED, LVFX IC (500 μg/0.1 mL), or IC saline. EDs were administered 0, 3, and 6 h after surgery. Changes on electroretinography (ERG) and intraocular bacterial growth were determined sequentially until 48 h after inoculation.

RESULTS

The concentrations of LVFX at 2 h after IC were higher in the aqueous humor and the vitreous cavity of eyes with or without PCR, compared with EDs or SCI. Eyes treated with LVFX ED, MFLX ED, or IC saline showed a significantly greater reduction in b-wave amplitude on ERG at 48 h compared with eyes treated with LVFX IC. The number of bacteria recovered from the vitreous humor in eyes treated with IC LVFX at 48 h was significantly less than from eyes that received other treatments.

CONCLUSION

The LVFX IC was effective at suppressing endophthalmitis caused by E. faecalis in eyes with a PCR.

Contribution of secreted proteases to the pathogenesis of postoperative Enterococcus faecalis endophthalmitis

PURPOSE

To determine how a secreted protease contributes to the pathogenesis of post-cataract endophthalmitis caused by Enterococcus faecalis using an aphakic rabbit endophthalmitis model.

SETTING

Department of Ophthalmology, Ehime University School of Medicine, Ehime, Japan.

METHODS

The pathogenesis of E faecalis OG1S (secreted protease-positive) and E faecalis OG1X (secreted protease-negative derivative of OG1S) was compared. After lens removal by phacoemulsification, either strain was inoculated into the lens bag. Changes in bacterial growth, electroretinography (ERG), and pathology of eyes were comparatively monitored throughout the course of the infection. Alternatively, culture fluid from either strain was injected into the vitreous body and ERG and pathology of the eyes were also examined.

RESULTS

The levels of growth in the anterior chamber and vitreous cavity were similar for both strains. However, infection with OG1S resulted in a significantly greater reduction in ERG b-wave amplitude than OG1X. Histological examination showed that the posterior lens capsules were severely affected in eyes infected with OG1S, and inflammatory cells and cocci were found in the anterior vitreous cavity 24 hours after the infection. By 48 hours, the retina architecture was profoundly affected in eyes infected with OG1S. In contrast, few pathological changes were noted in the posterior lens capsules and retina of eyes infected with OG1X. Culture fluid in which OG1S had grown decreased ERG b-wave amplitude and caused morphological changes of the posterior capsule and retina similar to those in the infected eye.

CONCLUSION

An extracellular protease plays a major role in the pathogenesis of E faecalis-induced postoperative endophthalmitis.

Endophthalmitis: a review of current evaluation and management

PURPOSE

To review the current state of evaluation and management of various forms of endophthalmitis.

METHODS

A review of the literature is included, encompassing endophthalmitis occurring after ocular surgeries, intravitreal injection, trauma, and systemic infection. Based on this review, current principles and techniques for evaluating and treating these forms of endophthalmitis are discussed.

RESULTS

Postoperative endophthalmitis after cataract surgery is the most common presentation. Conclusions from the Endophthalmitis Vitrectomy Study (EVS) remain a foundation for management of postcataract surgery endophthalmitis, notably prompt intravitreal antibiotic administration after vitreous sampling, with consideration for pars plana vitrectomy in severe cases. The potential impact of advances since the EVS, such as oral fourth generation fluoroquinolones and new vitrectomy techniques, are also discussed. The management of postcataract endophthalmitis is compared and contrasted to endophthalmitis occurring after other ocular surgeries, intravitreal injection, trauma, and systemic infection. Although some principles remain common, treatment rationales differ with other forms of endophthalmitis based on differing clinical circumstances, such as the virulence of organisms that are frequently encountered.

CONCLUSIONS

Endophthalmitis is a serious, potentially vision threatening condition which can present in various settings. Prompt recognition and treatment are key in maximizing outcomes.

Presumed infectious endophthalmitis following cataract surgery in the UK: a case–control study of risk factors

AIMS

To study risk factors for presumed infectious endophthalmitis complicating cataract surgery in the United Kingdom.

METHODS

Two hundred and fourteen clinically diagnosed patients with presumed infectious endophthalmitis were compared with 445 control patients throughout the United Kingdom in a prospective case-control study. The cases were identified through the British Ophthalmological Surveillance Unit reporting card system. Control patients undergoing cataract surgery from 13 'control centres' throughout the United Kingdom were selected randomly. Risk factors were identified by univariate and multivariate logistic regression analyses. Pertinent variables relating to the cataract extraction procedure, antimicrobial prophylaxis, ophthalmic and medical history were analysed with regard to postoperative infection.

RESULTS

Statistically significant risk factors in the multivariate model included inpatient cataract surgery (P=0.001), surgery in dedicated eye theatres (P<0.001), consultant grade surgeon (compared to registrar) (P=0.001), posterior capsule tear during cataract surgery (P=0.001). The use of face masks by the scrub nurse and surgeon during cataract surgery (P<0.001) and the administration of subconjunctival antibiotics at the end of surgery (P<0.001) were protective against postoperative infection.

CONCLUSIONS

In order to minimise the risk of postoperative endophthalmitis we would recommend the wearing of face masks by the surgeon and scrub nurse during cataract surgery and subconjunctival antibiotics at the end of surgery.

Postoperative endophthalmitis: caution is the watchword

Postoperative endophthalmitis is the most feared complication following cataract surgery. It can be caused by infection entering the eye during surgery or by inadequately cleaned instruments. Sterile phaco handpieces might retain remnants of soft lens matter or visco-elastic which might later contaminate other patients, causing inflammation in their eyes. The costs of an endophthalmitis outbreak are heavy, including poor patient outcomes, temporary theatre closure, rising waiting lists and damage to a hospital's reputation. This article raises awareness of endophthalmitis and provides useful recommendations for ophthalmic theatre personnel.

Sutureless ophthalmic surgery: a scaffold-enhanced bioadhesive technique

PURPOSE

Bioadhesives have had limited use in ophthalmic surgery. Problems with these adhesives have included inadequate tensile strength and difficulty with their application to the tissue site. We evaluated a scaffold-enhanced cyanoacrylate bioadhesive composite as an alternative to sutures in ophthalmic surgery, including strabismus procedures.

METHODS AND MATERIALS

The bioadhesive composite consisted of 2-octyl-cyanoacrylate combined with either a poly(L-lactic-co-glycolic acid) (PLGA) scaffold or a rehydrated porcine small intestine submucosa (SIS) scaffold. Extraocular rectus muscle and sclera were obtained from rabbits (n = 40) and were used, with these bioadhesive composites, to produce rectus muscle-to-sclera, sclera-to-sclera, and rectus muscle-to-rectus muscle adhesions. Control adhesions were created with cyanoacrylate only. The breaking load of the tissue repair was measured with a material strength-testing machine.

RESULTS

In all cases, the scaffold-enhanced cyanoacrylate adhesions were significantly stronger (P < 0.001) than the cyanoacrylate alone. The rectus muscle-to-sclera adhesions were greater than the in vivo forces reported for the horizontal rectus muscles in humans in extreme gaze.

CONCLUSION

This scaffold-enhanced bioadhesive composite produced initial muscle-sclera adhesions with strength satisfactory for strabismus surgery. It also may be applicable to other categories of ophthalmic surgery as a substitute for sutures.

Microbial contamination of the anterior chamber during cataract phacoemulsification and intraocular lens implantation in dogs

The objective of this study was to determine the frequency of intraoperative contamination of the anterior chamber with viable microorganisms during cataract phacoemulsification and intraocular lens implantation, and to evaluate the relationship of contaminant microorganisms to patients' extraocular and nasal cavity floras. Also, the impact of various aspects of the patient history and phacoemulsification procedure on the incidence of positive postoperative anterior chamber cultures was investigated. Twenty-two eyes from 13 dogs presented for elective cataract phacoemulsification and intraocular lens implantation were studied. Preoperatively, microbiologic samples of the conjunctiva, eyelid margins, nares, and rostral nasal cavity were collected. Postoperatively, anterior chamber fluid was aspirated. Samples were submitted for aerobic/anaerobic bacteriologic culture and antimicrobial susceptibility, Mycoplasma culture, and fungal culture. Anterior chamber aspirates collected at the conclusion of surgery were culture positive for at least one organism in 22.7% of eyes. Three aerobic bacteria and three fungi were isolated from the anterior chamber aspirates. Two fungi and one bacterium isolated from the anterior chamber were typed identically, and the bacterium had a similar antibiogram to organisms recovered from the patient's conjunctiva and eyelid margin. No statistically significant difference in contamination frequency was found for the investigated patient and surgical variables. We conclude that intraoperative contamination of the anterior chamber with viable bacterial and fungal organisms is a common occurrence in canine patients undergoing cataract phacoemulsification and intraocular lens implantation, and the external ocular flora is a likely source of some of these contaminating microorganisms. This contamination is independent of the patient and surgical variables investigated.

Retrocapsular lens fragments after uneventful phacoemulsification cataract surgery

PURPOSE

To analyze the factors influencing the risk for lens fragments in the retrocapsular space after uneventful phacoemulsification cataract surgery.

SETTING

Norfolk and Norwich University Hospital, Norwich, United Kingdom.

METHODS

Five hundred six consecutive patients who had uneventful phacoemulsification cataract surgery were examined intraoperatively for lens fragments in the retrocapsular space. Data collected for each patient included site of corneal incision, axial length, cataract nuclear density, phaco power and duration, and equivalent phaco time (EPT, calculated as a product of phaco power and duration). Statistical analysis was performed to determine the effect of each factor on the risk for developing retrocapsular lens fragments.

RESULTS

Retrocapsular lens fragments were present in 16.6% of patients. Univariate analysis showed that the duration of phacoemulsification and EPT were significantly longer in patients with retrocapsular lens fragments than in those without. Logistic regression showed that EPT was the only factor statistically significantly associated with the fragments. However, the effect of EPT on the odds ratio of developing fragments was small.

CONCLUSIONS

Lens fragments in the retrocapsular space occurred relatively frequently after uneventful phacoemulsification surgery. There was a small but statistically significant relationship between EPT and the risk for lens fragments.

Postoperative endophthalmitis: establishment and results of a national registry

PURPOSE

To determine the incidence, clinical presentation, etiology, and outcomes of postoperative endophthalmitis in Norway and to explore the potential of and establish a platform for improving diagnostics, prophylaxis, and treatment of postoperative endophthalmitis.

SETTING

All ophthalmic surgical units and relevant microbiology laboratories in Norway.

METHODS

A national registry of cases of postoperative endophthalmitis was established in 1996. All ophthalmic surgery units in Norway were asked to return forms including preoperative, perioperative, and postoperative data for each case of endophthalmitis occurring between January 1996 and December 1998 after any intraocular surgery irrespective of the time between the surgery and the onset of endophthalmitis symptoms. All microbiology laboratories in Norway were asked to return questionnaires regarding their routine handling procedures of eye specimens in cases of endophthalmitis.

RESULTS

From 1996 to 1998, 111 suspected endophthalmitis cases were reported, all after cataract surgery. Eighty cases were culture positive, 75 with gram-positive bacteria, 4 with gram-negative bacteria, and 1 with Candida albicans. Depending on the definition, the incidence of postoperative endophthalmitis was between 0.11% and 0.16%. Thirteen percent of cases had "delayed" endophthalmitis. Twenty-nine percent of eyes had an outcome of permanent amaurosis or light perception visual acuity; 56% (47/84) retained or improved their categorized visual acuity in the affected eye compared to preoperatively. Positive bacterial growth was associated with a worse visual outcome (P =.008). The degree of inflammation when endophthalmitis was diagnosed and the visual outcomes were worse in cases with growth of streptococci than in cases with growth of staphylococci (P =.009 and P<.001, respectively). The questionnaire to the microbiology laboratories revealed a lack of consensus on how to handle the specimens.

CONCLUSIONS

Postoperative endophthalmitis remains a serious complication of intraocular surgery, although the prognosis depends greatly on the microbe isolated. Common guidelines should be established regarding clinical and microbiological diagnosis and treatment. Further improvement of the registry would make it a suitable platform for evaluating prophylactic treatments.

Microbial contamination of the anterior chamber during phacoemulsification

PURPOSE

To study the nature and frequency of anterior chamber contamination during phacoemulsification.

SETTING

Department of Ophthalmology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India.

METHODS

Eighty eyes of 80 patients having routine phacoemulsification cataract surgery were recruited into this prospective study. Bacterial cultures from the intraoperative anterior chamber aspirates from the patients were assessed.

RESULTS

Anterior chamber fluid aspirates were positive for bacteria in 37 eyes (46.25%). Coagulase-negative Staphylococcus was the most common aerobe and Propionibacterium acnes, the most common anaerobe.

CONCLUSION

Results indicate that phacoemulsification has no proven advantage over conventional extracapsular cataract extraction in reducing intraoperative bacterial contamination.

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.

Endophthalmitis in the western Sydney region: a case-control study

BACKGROUND

A retrospective case-control study was conducted to investigate risk factors for endophthalmitis following routine intraocular surgery.

METHODS

A review was performed of consecutive cases of endophthalmitis from three teaching hospitals in the western Sydney region and matched controls from the same institutions between 1996 and 1998.

RESULTS

There were 31 cases and 66 controls. Eighty procedures were phacoemulsification, 15 conventional extracapsular cataract extraction, and two were penetrating keratoplasties. Of the 80 patients who had phacoemulsification surgery, 50 had a clear corneal incision, and 26 had a scleral incision (four were unknown). Logistic regression showed an increased risk of endophthalmitis with surgical complications (P = 0.002) and clear cornea temporal incisions (P = 0.007). Risk of endophthalmitis was reduced with use of subconjunctival injections (P = 0.008). The yield for the Gram stain was 47% and for culture was 67%. Anterior chamber tap in addition to vitreous biopsy alone did not increase the yield for microorganism (P = 0.78). Mean visual acuity on presentation was hand movement with 13 patients (50%) showing visual improvement following intravitreal injections of antibiotics (P = 0.003). Visual prognosis did not correlate with presenting visual acuity but appeared to be better in those who grew Staphylococcus epidermidis or were culture negative.

CONCLUSIONS

Although this study is unable to draw definite conclusions regarding risk of endophthalmitis in clear corneal temporal cataract surgery, sufficient data suggest the importance of incision type and location. Surgical complication is an important risk factor for endophthalmitis. Use of subconjunctival antibiotic injections at the conclusion of the procedure is recommended.

Incidence of endophthalmitis after cataract surgery in the Netherlands: several surgical techniques compared

In order to investigate the incidence of endophthalmitis following various types of cataract surgery, we sent a questionnaire to the members of the Dutch Intraocular Implant Club (NIOIC). Retrospectively, information was obtained about the number of performed cataract extractions, the techniques used, and the number of patients with postoperative endophthalmitis. To estimate bias by underreporting, we calculated the nationwide incidence of endophthalmitis after cataract surgery in the same period of time. The response rate to the questionnaire was 51.2%. In the reporting group the incidence of endophthalmitis was 0.11%. This incidence was comparable with the calculated nationwide incidence (0.15%). Comparison between the incidences after phacoemulsification (0.10%) and after other techniques (0.16%) showed no significant difference in the questionnaire group. A complicated cataract extraction preceded 12 out of the 38 reported cases with endophthalmitis. In conclusion, the incidence of endophthalmitis after cataract surgery in the Netherlands is comparable with the incidence reported in literature. The occurrence of complications during surgery rather than the technique used affects on the development of endophthalmitis.

Prospective evaluation of external ocular microbial growth and aqueous humor contamination during cataract surgery

PURPOSE

To analyze the route of aqueous humor contamination leading to the development of postoperative endophthalmitis.

SETTING

Department of Ophthalmology, University of Helsinki, Finland.

METHODS

Forty-nine eyes of 49 patients (31 having phacoemulsification and 18 extracapsular cataract extraction [ECCE]) participated in the study. Four bacterial cultures were taken: preoperative conjunctival swab, lid margin culture, intraoperative lacrimal lake sample, and immediate postoperative anterior chamber fluid sample.

RESULTS

Preoperative lid margin cultures were positive in 59.2% of eyes, conjunctival cultures in 69.4%, and lacrimal lake cultures in 24.9%. Four aqueous humor samples (8.2%) showed bacterial growth in the anterior chamber aspirate: 3 in the phacoemulsification and 1 in the ECCE group. The bacteria isolated in this study, Staphylococcus epidermidis and Propionibacterium acnes (2 positive isolates each) were sensitive to the preoperative topical antibiotics used. No aqueous humor sample or any from other locations showed gram-negative microbe growth. The most frequently recovered microbes in all samples collected from the 3 other sources were S epidermidis and other coagulase-negative staphylococcus species, followed by P acnes and other propionibacterium species. Staphylococcus aureus, and diptheroids.

CONCLUSION

The ocular surface significantly contributed to the transmission of microbes into the eye during cataract surgery. These microbes could not be eradicated by topical preoperative antibiotics. However, no patient developed postoperative endophthalmitis. Natural defense mechanisms appear to fend off a minor inoculum with these microbes of relatively low pathogenicity.

Endophthalmitis after cataract surgery: risk factors relating to technique and events of the operation and patient history: a retrospective case-control study

OBJECTIVE

This study aimed to investigate the relationship between postoperative endophthalmitis and current changes in the cataract operative technique.

DESIGN

A retrospective case-control study.

PARTICIPANTS

The 22,091 cataract operations performed from 1990 through 1993 at St Eriks Hospital formed the basis for this investigation. In a random fashion, 220 control subjects were selected to be compared with the endophthalmitis cases.

MAIN OUTCOME MEASURES

Numerous variables pertaining to the cataract extraction procedure and to the ocular and general health of patients with cataracts were analyzed regarding the development of postoperative intraocular infection. Patient age, presence of diabetes or immunosuppression, type of cataract extraction and intraocular lens (IOL), and intraoperative or postoperative complications were the principal variables assessed.

RESULTS

Fifty-seven patients with endophthalmitis were diagnosed, resulting in an overall frequency of 0.26%. Immunosuppressive treatment (P = 0.019), wound abnormality (P = 0.03), and the use of IOLs without a heparinized surface (P = 0.0023) were the only significant risk factors found in a logistic regression model.

CONCLUSIONS

The results suggest that cataract operating practice may alter the risk for endophthalmitis in that implanting a heparinized IOL and creating a tight section both seem to provide protection against this dreaded complication. Regarding patient history, an increased susceptibility was found among subjects treated with immunosuppressants. Designing a prophylactic protocol that protects against endophthalmitis more efficiently than did the study prophylaxis of 20 mg of subconjunctival gentamicin, is important not only for this patient subgroup but also for the cataract operated population at large.

Measurement of electrostatic charge on intraocular lenses

PURPOSE

An electronic meter that measures electrostatic charge was designed and built. The hypothesis tested was that an intraocular lens (IOL) attains a charge during handling in the operating theatre and that washing the IOL with balanced salt solution (BSS) would result in a reduction in the surface charge. Once exposed to the air a charged IOL may attract particulate matter to its surface before implantation into the eye.

METHODS

This experiment was performed in the operating theatre under sterile conditions mimicking cataract surgery. The lens box was opened onto a trolley and the lens container opened by a scrubbed assistant. The operator (also scrubbed) removed the lens with MacPherson's forceps. The charge on the lens was then measured without delay, or after the lens had been washed with 1-2 ml of BSS.

RESULTS

The mean charge on unwashed lenses was 1.43 x 10(-10) C (n = 12) and on washed lenses was 0.59 x 10(-10) C (n = 10). The difference in the charges was significant (p = 0.03, unpaired t-test).

CONCLUSION

Washing of an IOL prior to implantation will reduce the surface charge and is therefore also likely to reduce the chance of contamination.

Heparinised intraocular infusion and bacterial contamination in cataract surgery

BACKGROUND/AIMS

Heparin in solution reduces bacterial adhesion to intraocular lenses and a lower incidence of postoperative endophthalmitis has been reported with the use of heparin coated lenses. The safety of adding low molecular weight heparin to the infusion fluid during routine cataract surgery was investigated. Any direct antibacterial effect was looked for by culturing anterior chamber fluid samples taken at the completion of surgery.

METHODS

A randomised, double blind, controlled study of 111 patients undergoing routine cataract surgery. Low molecular weight heparin at a concentration of 5 IU/ml was added to the infusion fluid in the trial patients. Samples from the anterior chamber taken at completion of surgery were cultured. Twenty nine samples of sterile infusion fluid were also cultured as further controls.

RESULTS

No complications were found in either group, and no difference in observed postoperative inflammation in each group. In the heparinised group (n = 55) bacterial contamination was found in 31% of samples, compared with 27% in the no heparin group (n = 56) (no significant difference).

CONCLUSIONS

There appears to be no direct antibacterial effect of heparin, and other possible mechanisms of action are discussed. Heparin avoids many of the drawbacks of traditional antibiotic prophylaxis and may have the potential to be a safe and effective addition to endophthalmitis prevention.

Epidemic Bacillus endophthalmitis after cataract surgery I: acute presentation and outcome

OBJECTIVE

The purpose of the study is to report the clinical outcome of acute Bacillus endophthalmitis after cataract surgery.

DESIGN

The study design is a cohort study.

PARTICIPANTS

Fourteen eyes of 14 patients with epidemic acute postoperative inflammation after exposure to bacteria-contaminated viscoelastic material were studied.

INTERVENTION

Three patients with milder clinical presentations were treated without vitrectomy or antibiotics. Eleven patients with more severe infection were treated with vitrectomy as well as intravitreous and topical fortified antibiotics.

MAIN OUTCOME MEASURES

Final visual acuities were obtained in all 14 study patients. Results of microbiologic studies of aqueous and vitreous specimens from 11 vitrectomized eyes also were analyzed.

RESULTS

One patient with late presentation had severe inflammation and had phthisis bulbi develop with no light perception. The remaining 13 patients had successful resolution of inflammation after treatment by 1 month of follow-up. Twelve of these 13 patients, including 1 nonvitrectomized patient, had final visual acuities of 20/100 or better at 6 months' follow-up. Six patients, including two patients with nonvitrectomized eyes, had outcomes of 20/40 or better visual acuity. Bacillus species were grown from all 11 (100%) vitreous and 7 (88%) of 8 aqueous specimens obtained from vitrectomized patients, as well as from the contaminated viscoelastic material remaining in the operating room.

CONCLUSIONS

Postoperative Bacillus endophthalmitis need not result in poor outcome. Results depend on factors including bacterial load, specific bacterial species, timing of treatment, and immune status of the patient.

Peroperative microbial contamination of anterior chamber aspirates during extracapsular cataract extraction and phacoemulsification

BACKGROUND

The normal conjunctival flora is one of the main sources of intraocular contamination during cataract surgery. The theory that the positive anterior chamber (AC) pressure during phacoemulsification (phaco), and the smaller wound utilised, might reduce the rate of contamination was studied.

METHODS

The peroperative AC aspirates of 210 consecutive patients undergoing cataract surgery were assessed. In group 1, 100 patients underwent a standard extracapsular cataract extraction (ECCE). In group 2, 110 patients underwent phacoemulsification of the crystal-line lens through a scleral tunnel. AC aspirates from the Simcoe irrigation/aspiration cannula (group 1) and phaco probe (group 2) were collected and microbiological studies performed after direct and enrichment cultures.

RESULTS

There were 29 (29%) positives in the ECCE group compared with 22 (20%) positive cultures from AC aspirates in the phaco group. Coagulase negative staphylococcus (CNS) was the commonest contaminant in both groups.

CONCLUSION

Although there was a higher rate of AC contamination during ECCE, the difference was not statistically significant (p > 0.10, chi 2 = 2.31).

Prophylactic antibiotics in cataract operations

The rationale for prophylactic antibiotics in cataract operations must be continually reevaluated in light of cost-effectiveness and adverse reactions. The principles learned from wound infections associated with general surgical procedures should be applied to the limited knowledge about the rare event of endophthalmitis. Herein the literature on experimental and clinical wound infections in general surgical procedures is reviewed, with analysis of microbial flora, pathophysiology of wound infections, and pharmacokinetics of antibiotics. Experimental and clinical studies on prophylactic antibiotics to prevent endophthalmitis are reviewed, including information on topically applied antibiotics, chemical antisepsis, and administration of subconjunctival, intracameral, and systemic antibiotics. In addition, the benefits, limitations, and risks of the various types of prophylactic antibiotics are discussed. Because of the limited data on prophylactic antibiotics in cataract operations, providing dogmatic statements is difficult. General recommendations are offered based on the currently available literature, and a stratified approach is suggested based on wound construction and number of anterior segment maneuvers.

Bacterial anterior chamber contamination with foldable silicone lens implantation using a forceps and an injector

PURPOSE

To compare the rate of anterior chamber (AC) contamination during implantation of a foldable three-piece silicone lens using a forceps and an injector.

SETTING

Department of Ophthalmology, University of Saarland, Homburg (Saar), Germany.

METHODS

In a prospective, randomized study, we cultured AC aspirates of patients who had phacoemulsification with silicone lens implantation through a 3.5 mm temporal clear corneal incision. In Group A, the lens was implanted with a forceps and in Group B, with an injector. Immediately after lens implantation, the AC aspirate (0.05 to 0.10 ml) was collected and sent to the microbiology department. All cultures were incubated for 3 days. As a topical antibiotic, gentamicin was given preoperatively and intraoperatively.

RESULTS

One hundred patients (50 in each group) were examined. In each group the bacterial contamination of the AC was 2%.

CONCLUSION

Bacterial contamination of the AC was not significantly different after silicone lens implantation with a forceps and with an injector.

In vitro bacterial adherence to hydrogel and poly(methyl methacrylate) intraocular lenses

PURPOSE

To compare the in vitro adherence of Staphylococcus epidermidis to poly-(hydroxyethyl methacrylate) (polyHEMA) or hydrogel intraocular lenses (IOLs) and poly(methyl methacrylate) (PMMA) IOLs.

SETTING

Lions Eye Institute, Perth, Western Australia.

METHODS

One-piece hydrogel lenses and one-piece PMMA lenses were suspended for 60 minutes in standardized suspensions of a well-characterized strain of S. epidermidis and then sonicated in a known quantity of balanced salt solution to remove the adherent bacteria. Quantitative cultures of the sonicates were performed and the results analyzed statistically.

RESULTS

The mean bacterial adherence of S. epidermidis to the PMMA IOLs (58,400 CFU) was more than 20 times greater than that to the hydrogel IOLs (1953 CFU). The difference was statistically significant (P < .001).

CONCLUSIONS

Adherence of S. epidermidis to hydrogel IOLs is significantly lower than to PMMA IOLs. This suggests that the risk of postoperative endophthalmitis after cataract extraction and IOL implantation may be lower with the use of hydrogel IOLs.