Intraocular lens implants and risk of endophthalmitis.

Br J Ophthalmol 1998;82:1312–1315
Intraocular lens implants and risk ofendophthalmitis J W B Bainbridge, M Teimory, H Tabandeh, J F Kirwan, R Dalton, F Reid, C K Rostron Abstract
Materials and methods
Aim—To investigate the possible associ-
A retrospective study was conducted to iden- ation between the use of three piece
tify the incidence of endophthalmitis following foldable silicone polypropylene (SPP) in-
cataract surgery at our unit during a 3 year traocular lenses (IOLs) and an increased
period by means of a systematic review of risk of postoperative endophthalmitis.
operating theatre records and patient case Methods—A retrospective analysis was
notes. Data on age, sex, type of procedure conducted of all cases of postoperative
(conventional extracapsular cataract extraction endophthalmitis following phacoemulsifi-
or phacoemulsification), and IOL type were cation surgery in a single unit over a 3 year
collected for all patients undergoing cataractsurgery during the study period. The diagnosis period. The incidence of postoperative
of endophthalmitis was made clinically, on the endophthalmitis in eyes with SPP IOLs
was compared with the incidence in eyes
associated with hypopyon and cellular infiltrate with single piece polymethylmethacrylate
of the vitreous, and was confirmed by positive (PMMA) IOLs.
microbiological cultures following aqueous tap Results—772
cataract
extractions
or vitreous biopsy. The relative risk of postop- phacoemulsification were performed. One
erative endophthalmitis associated with the use (0.16%) of the 622 patients with PMMA
IOLs developed endophthalmitis. Exclud-
was calculated. Fisher’s exact test (EPI-INFO ing one patient who had aplastic anaemia,
five (3.33%) of 150 patients with SPP IOLs
USA) was used to establish the significance of 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).
A total of 772 patients underwent cataract sur- Conclusion—This study adds further evi-
gery by phacoemulsification with intraocular dence to the concept that SPP IOLs can be
lens implant during the study period. There a significant risk factor in the develop-
were 470 (61%) females and 302 (39%) males ment of postoperative endophthamitis.
with an age range of 12–101 years and a mean (Br J Ophthalmol 1998;82:1312–1315)
age of 73.4 years (females 75, males 71). Therewas no significant diVerence in mean age(p=0.74) or male:female ratio (p=0.31) be- Postoperative endophthalmitis remains a seri- ous sight threatening complication of cataract cases of postoperative endophthalmitis were surgery. Despite improved antiseptic and anti- identified (Table 1) with an overall incidence of microbial prophylaxis the incidence of endoph- 0.91%. In five cases the diagnosis was con- Department of
thalmitis following cataract surgery is quoted firmed by microbiological cultures. In the two Ophthalmology,
as 0.08%–0.12%.1–5 In many cases the organ- culture negative cases the diagnoses were made St George’s Hospital,
isms involved are thought to originate from clinically on the basis of symptoms of pain and London SW17 0QT
periocular flora.6 These organisms may gain redness associated with hypopyon and cellular Before surgery, one patient had a history of instruments, the irrigation fluid,7 or by con- tamination of the intraocular lens implant patients had no pre-existing abnormalities of the itself.8 Adherence of bacteria to IOLs results operated eye. One patient had aplastic anaemia, from electrostatic charges and is enhanced by one had a history of chronic alcohol depend- Department of
the formation of polysaccharide biofilms. The ence, and another patient had undergone aortic Medical Statistics,
propensity of bacteria to adhere to IOLs may valve replacement 9 months previously. The St George’s Hospital
vary according to the lens material. A previous procedures were performed by a total of four Medical School,
report has suggested an association between London SW17 0QT
surgeons and no one surgeon was involved in the use of an intraocular lens with haptics more than three of the seven cases. All cases made of polypropylene and an increased risk of underwent uncomplicated phacoemulsification postoperative endophthalmitis.9 This study with implantation of the intraocular lens into the capsular bag. The six eyes which received folding SPP IOLs (Allergan S13ONB) had 3.2 polypropylene (SPP) and single piece poly- mm clear corneal stab incisions (superiorly in methylmethacrylate (PMMA) intraocular lens four cases and temporally in two) extended to 3.5 mm for insertion of the IOL and sutured Intraocular lens implants and risk of endophthalmitis with a continuous 10/0 nylon X suture. The eye which received a rigid 5.5 mm PMMA IOL(Iolab MC550) had a superior sutureless 3.5 mm scleral tunnel. The surgical technique was otherwise similar between the two groups and did not change during the study period. At theconclusion of the procedure five patients re- ceived gentamicin subconjunctivally, one re- ceived topical chloramphenicol ointment, and one patient received no antibiotic prophylaxis at this point because of a history of drug sensitivity.
Postoperatively all patients were prescribed a 4 week reducing course of topical dexamethasone, neomycin, and polymixin B to the operated eye.
cataract extraction with clinical evidence of acute endophthalmitis. A vitreous biopsy was performed in five patients and anterior cham- ber tap in two; coagulase negative staphylo- cocci were isolated from three (in addition to Pseudomonas sp in the patient with aplasticanaemia), Staphylococcus aureus from one patient, and samples from one patient were culture negative. One patient did not undergo intraocular fluid sampling and was treated empirically. One patient presented 4 months postoperatively with a chronic low grade ante- rior uveitis which became more severe follow- ing YAG laser posterior capsulotomy. Vitreous received a SPP IOL had a history of idiopathic aplastic anaemia. Despite transfusions this patient was significantly neutropenic in theearly postoperative period and for this reason is excluded from the statistical analysis.
Of the 772 patients who underwent cataract extraction by phacoemulsification during the 150 patients received SPP IOLs. Postoperative endophthalmitis developed in one (0.16%) of (3.33%) of those with SPP IOLS. The relativerisk of postoperative endophthalmitis associ- ated with the use of the SPP IOL compared with the PMMA IOL was 20.73 (95% CI=2.44 to 176.16) (p=0.0013).
If the two cases of culture negative endoph- thalmitis are excluded, endophthalmitis devel- SPP IOLs. The relative risk of postoperative endophthalmitis associated with the use of the Patients with endophthalmitis according to IOL *Fisher’s exact test, SPP = silicone polypropylene; PMMA = Bainbridge, Teimory, Tabandeh, et al ence of Staph epidermidis to lenses with 12.61 (95% CI 1.32 to 120.35) (p=0.024).
treated with topical and systemic antibiotics method, a radioisotope technique, and scan- and six received intravitreal antibiotics. In two ning electron microscopy.12 In a qualitative patients the IOL was explanted. The final study using scanning electron microscopy Dilly visual acuities were 6/9 or better in four patients, 6/12 in two patients, and 6/18 in one adhere to polypropylene haptics in preference to the PMMA optic of a three piece intraocularlens, both in vitro and in vivo.13 They also Discussion
noted that the surface of the polypropylene This study suggests an association between the haptic appeared relatively irregular.
use of three piece silicone polypropylene intraocular lenses and an increased risk of micro-organisms organised within an extensive postoperative endophthalmitis following un- exopolymer matrix14 which confers relative protection from humoral and cellular immu- The authors acknowledge the limitations of nity and from antibiotics. Bacteria introduced this retrospective study. There was no signifi- at the time of surgery may become sequestered cant diVerence in mean age or sex distribution within a biofilm on the IOL or on the capsule.15 between the patients in the two IOL groups but GriYths et al showed that adherence of Staph other possible confounding elements cannot be epidermidis to IOLS in vitro appears to confer greater resistance to antibiotics10 and investigate the influence of possible confound- Cusumano et al demonstrated that bacterial ing variables using multivariate analysis be- growth in vitro is significantly enhanced on cause the number of cases with endophthalmi- silicone IOLs.16 This resistance to antibiotics tis was small. Patient allocation to IOL type and enhancement of bacterial growth may be was unrandomised and consequent selection due to diVerences in the surface properties of bias may have contributed to the observed the diVerent IOL types with diVering propensi- association. Although the procedures were per- formed by diVerent surgeons with unstandard- Adherence of bacteria to IOLs is likely to ised operative technique and diVering prophy- occur during the period immediately before lactic antimicrobial regimens, the surgical implantation. The presence of therapeutic protocol did not change otherwise during the levels of antibiotics at the time of IOL implan- study period and we could identify no consist- tation may be eVective in limiting further bac- ent diVerences in technique between the two terial proliferation. This can be achieved by groups. Despite the limitations in method- systemic or local administration. Topical and ology, in the absence of a randomised control- subconjunctival antibiotics are in common use led study we feel that the findings of this series and the potential of intracameral antibiotics add weight to existing evidence supporting an has more recently been a subject of intense association between the use of SPP IOLs and an increased risk of postoperative endoph- this small series are notable for their relatively There are a number of possible explanations good outcomes with six out of seven (86%) for the association. The use of folding silicone patients achieving final visual acuities of 6/12 lenses may entail considerable manipulation or better. Although the diVerence is not statis- after removal from the sterile packaging and tically significant these figures compare favour- before insertion into the eye. Although we ably with those of a larger series where 60% know of no evidence to confirm this possibility, achieved final visual acuities of 6/12 or better.18 such manipulation may increase the risk of Explantation of IOLs in postoperative endoph- thalmitis has been associated with an improved The lens materials or design may predispose visual outcome.19 The fact that IOL explanta- to bacterial contamination of the implant tion was performed in two cases in our series before insertion or may confer greater resist- ance of intraocular organisms to physiological mechanisms. Bacteria adhere to surfaces by thalmitis with SPP IOLs was first suggested in reversible adsorption due to physical forces a previous retrospective case-control study but such as electrostatic charge and hydrophobic- the need for further evidence was expressed ity, and by irreversible adherence involving before firm conclusions could be drawn.9 On the basis of the findings of this study the biofilm.10 Coagulase negative staphylococci are authors believe that where SPP IOLs are used, the organisms most commonly implicated in postoperative endophthalmitis,1 6 11 as was the particular attention given to early antibiotic case in this series, and are also associated with prophylaxis. A randomised controlled trial of infections complicating the implantation of SPP IOLs is required to further investigate other surgical prosthetic devices. GriYths et al their possible association with postoperative demonstrated the adherence of Staphylococcus epidermidis to intraocular lenses by microscopyand viable bacterial counting.10 Raskin et al have demonstrated a twofold greater adher- Intraocular lens implants and risk of endophthalmitis 1 Kattan HM, Flynn HW, Plugfelder SC, et al. Nosocomial 11 Schanzlin DJ, Goldberg DB, Brown SI. Staphylococcus epi- endophthalmitis survey; current incidence of infection after dermidis endophthalmitis following intraocular lens im- intraocular surgery. Ophthalmology 1991;98:227–38.
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2 Javitt JC, Street MPH, Tielsch JM, et al. National outcomes 12 Raskin EM, Speaker MG, McCormick SA, et al. Influence of cataract extraction; retinal detatchment and endoph- of haptic materials on the adherence of staphylococci to thalmitis after outpatient cataract surgery. Ophthalmology intraocular lenses. Arch Ophthalmol 1993;111:250–3.
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18 Endophthalmitis Vitrectomy Study Group. Results of the 8 Vafidis GC, Marsh RJ, Stacey AR. Bacterial contamination of intraocular lens surgery. Br J Ophthalmol 1984;68:520–3.
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