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

Experimental evaluation of the injection force exerted in intraocular lens delivery with syringe-type injectors

The process of intraocular lens (IOL) delivery within the capsular bag during cataract surgery is crucial, as the integrity of the IOL, the injector and the ocular structures should be preserved at all times. This study aims to obtain the main parameters that affect the injection force exerted in the ejection of an intraocular lens (IOL) through syringe-type injectors. For that purpose, ejection tests were carried out in vitro, measuring the resistance force throughout the entire delivery process. The effect of IOL material, haptic design, IOL thickest area and ophthalmic viscosurgical device (OVD) was studied by ejecting seven IOLs with four syringe-type injectors of different sizes, 3.0, 2.2 and 1.8 mm. In all injectors, plate hydrophilic IOLs present the lowest resistance forces; hydrated C-loop hydrophobic IOLs present higher forces and the C-loop hydrophobic IOL in dry conditions presents the highest resistance forces. All IOLs could be properly delivered with an injector size of 2.2 mm, making injector sizes of 3.0 mm outdated. The injector size of 1.8 mm damaged several IOLs. IOL material and cartridge nozzle size were the most influential parameters in IOL delivery. IOL thickest area was also relevant but in a lesser extent whereas IOL haptic design was not as relevant.

Anterior chamber bacterial contamination in cataract surgery

Background

The incidence of postoperative endophthalmitis has reduced during last several years to <0.01%; however, its associated complications continue to be devastating. Several sources of infection, including contamination by air, solutions, surgical instruments, intraocular lens, and wound leakage have been identified. The objective of this study was to evaluate the surgical technique, antibiotics, and asepsis that are used to reduce the risk of infection during cataract surgery.

Methods

This was a transversal prospective study, in which 64 cataract surgeries were evaluated from 32 patients, with 1 month recovery time; and cultures from preoperative and postoperative aspirates were analyzed. Two groups were established based on whether preoperative antibiotics were given or not. The analysis employed descriptive statistics.

Results

Of the 32 patients whose aspirates were obtained, three (9.37%) and 10 (31.25%) yielded positive cultures preoperative and postoperatively respectively. Staphylococcus species was the most common contaminating bacteria. The isolation of Staphylococcus species may indicate its potential as exogenous contaminant at time of wound closure. The cultures obtained from patients using preoperative antibiotics were positive for S. aureus in 10% (n = 2) of cases, and positive in 8.33% (n = 1) of cases not using antibiotics. The mean transoperative time with positive growth was 67 ± 17.8 minutes, and with negative growth was 76.3 ± 25.2 minutes. Two surgical techniques were evaluated: phacoemulsification and extracapsular extraction. The extracapsular technique showed a contamination rate of 33.33% (n = 8) compared to phacoemulsification with a rate of 25% (n = 2) (RR = 1.33).

Conclusions

Common contaminating microorganisms included the Staphylococcus species, which was isolated from the eyelids and ocular annexes at the time of wound closure. The isolation of microorganisms postoperatively could have been influenced by the surgical technique used, the surgical time, and the use of antibiotics.

Risk factors for acute endophthalmitis following cataract surgery: a systematic review and meta-analysis

Background

Acute endophthalmitis is one of the most serious complications of cataract surgery and often results in severe visual impairment. Several risk factors for acute postoperative endophthalmitis (POE) following cataract surgery have been reported but the level of evidence and strength of association is varied. The purpose of this study was to critically appraise published reports on and to summarize clinical risk factors associated with acute POE which could be easily assessed by ophthalmologists for the introduction and implementation of preventive measure.

Methods

A systematic review and meta-analysis of observational studies was performed. Six databases were searched with no limits on the year or language of publication. Study-specific odds ratios (Ors) or relative risk (RR) of each risk factor were pooled using a random effect model.

Results

A total of 6 686 169 participants with 8 963 endophthalmitis in 42 studies were analyzed. Of the nine risk factors identified in our systematic review and meta-analysis, extra- or intracapsular cataract extraction, a clear corneal incision, without intracameral cefazolin (1 mg in 0.1 ml solution), without intracameral cefuroxime (1 mg in 0.1 ml solution), post capsular rupture, silicone intraocular lenses and intraoperative complications were found strongly associated with acute endophthalmitis. Other significant factors with a lower strength of association (risk estimates generally 1.5 or less) were male gender and old age (85 years and older).

Conclusions

Our study provides summary data on the risk factors for acute POE. Identifying patients at high risk of this sight-threatening eye disease is important from both the public health and clinical perspectives as this would facilitate detection of disease before the onset of irreversible visual loss enabling earlier intervention.

Prophylaxis of postoperative endophthalmitis following cataract surgery: current status and future directions

Endophthalmitis is an uncommon but potentially devastating intraocular infection that can occur after routine cataract surgery. Although a broad spectrum of organisms have been shown to cause acute postoperative endophthalmitis, most cases are caused by Gram-positive bacteria, which may be introduced at the time of surgery from colonization of adjacent conjunctiva or eyelid skin. Risk factors for the development of endophthalmitis following cataract surgery include patient age, intraoperative surgical complications and poor wound construction. There are several antibacterial strategies employed to prevent postoperative endophthalmitis, with topical, intracameral and subconjunctival delivery being the most common. Worldwide, there seems to be significant regional variance in the type and method of prophylactic antibacterial regimens; for example, topical fluoroquinolones are commonly used in the US, while intracameral cephalosporins are employed widely in Europe. The optimal antibacterial strategy for the prevention of endophthalmitis should be safe, inexpensive and broad in microbiological activity spectrum, while not requiring patient compliance for its effectiveness.

Acute endophthalmitis after cataract surgery at a referral centre in Northern Taiwan: review of the causative organisms, antibiotic susceptibility, and clinical features

PURPOSES

The aims of this study were to describe the bacterial isolates and treatment outcomes of endophthalmitis after cataract surgery at a referral centre in Northern Taiwan.

METHODS

This was a retrospective, interventional, and observational series. Medical records were review of patients with clinical diagnosed, and/or culture-proven bacterial endophthalmitis at a tertiary referral centre in Northern Taiwan from January 2002 to December 2008. Treatment generally conformed to standard guidelines. Main outcome measurements were results of organism culture, antibiotic susceptibility of isolated bacteria, and visual acuity (VA) outcome.

RESULTS

Thirty-four patients had positive cultures. A total of 55.9% of the culture-positive isolates were Gram negative and 44.1% were Gram positive. Pseudomonas aeruginosa was the most commonly isolated organism. Eighteen patients had final VA better than 5/200, and 41 had final VA worse than 5/200. In multiple linear regression analysis, female gender, presence of hypopyon, and worse baseline VA were significant independent predictors of worse visual outcome.

CONCLUSIONS

It was found that at a referral centre in Northern Taiwan, the majority of bacterial isolates were Gram negative in acute postoperative bacterial endophthalmitis after cataract surgery and P. aeruginosa was the most common bacterial isolate.

[Intraocular lens and cataract surgery: comparison between bacterial adhesion and risk of postoperative endophthalmitis according to intraocular lens biomaterial]

Cataract surgery is a usually successful procedure that restores vision by replacing the natural lens with an intraocular lens (IOL). Acute postoperative endophthalmitis is still one of the most serious complications of cataract surgery. Its incidence has been reported to be between 0.04% and 0.32%. Precisely why bacteria induce endophthalmitis is not entirely understood. Indeed the risk of its development may be influenced by several factors. Among them, bacterial adhesion to the IOL has been recently emphasized in the ophthalmology literature. Indeed, the ability of an organism to adhere to the IOL surface is believed to be associated with a risk of infection at the implantation site. Several studies have demonstrated that bacterial adhesion is influenced by IOL materials. Ever since, numerous studies have investigated the interactions between bacteria and different types of IOLs to determine which biomaterial would be most permissive to bacterial adherence. This article reviews all the epidemiological and experimental data relating to the study of the relationship between bacterial adhesion, IOL material, and risk of developing postoperative endophthalmitis. Even if discrepancies between these studies exist, mainly stemming from the use of different experimental conditions and protocols, it seems that bacterial adhesion is strongly influenced by IOL material. Epidemiological studies suggest that the implantation of silicone IOLs might be associated with increased rates of endophthalmitis. Experimental studies reach similar conclusions showing that hydrophobic IOLs such as silicone or acrylic hydrophobic IOLs are more permissive to bacterial adhesion and growth than hydrophilic IOLs such as acrylic hydrophilic IOLs. Among the interactions that govern bacterial attachment to the IOLs, it seems that hydrophilic-hydrophobic interactions have the greatest influence. Nevertheless, since bacterial adhesion is a complicated process affected by many factors, the conclusions drawn by these results have to be interpreted with care. Further investigations are still needed to understand the connections between IOL material and endophthalmitis.