Adherence test of Staphylococcus epidermidis on the surface of different material intraocular lenses

Abstract

Background Postoperative endophthalmitis following intraocular lens(IOL)implantation is still one of the most feared complications of cataract surgery.Bacterial adhesion to IOLs during their insertion is a prominent etiological factor.The adhesion characteristics of bacteria to IOL are very vital for the prevention of endophthalmitis after cataract surgery.Objective The present study was to observe the in vitro adherence ability of Staphylococcus epidermidis to different intraocular lenses(IOLs)and compare the results in bacterial counting between scanning electron microscopy(SEM)photographs and quantitative cultures. Methods Five types of IOLs,including hydrophobic acrylic IOL,polymethylmethaerylate(PMMA)IOL,heparin-surface-modified(HSM) PMMA IOL,silicone(SI)IOL and hydrophilic acrylic IOL,were put into S.epidermidis(ATCC 12228)suspension for 1 hour.The bacterial adhesion numbers on the IOL surfaces were counted by quantitative cultures and scanning electron microscopy(SEM) photographs. Results Quantitative culture counting of viable adherent bacteria released by sonication showed that hydrophobic acrylic IOL and PMMA IOL were more likely for bacteria to attach.The number of bacteria on the five types of IOL surfaces showed significant differences(F=100.084,P=0.000).No significant differences were found in the number of bacteria between hydrophilic acrylic IOL and HSM-PMMA IOL (t=2.285,P=0.052)with the quantitative culture method.Direct counting of adherent bacteria in SEM photographs revealed that there were significant differences in bacterial adhesion numbers among difierent IOL material groups,with the numbers from high to low as follows:Hydrophobic IOL＞PMMA IOL＞SI IOL＞Hydrophilic IOL＞HSM-PMMA IOL(F=118.065,P=0.000).The counting method by SEM method was superior to that by quantitative cultures (t=5.019,P=0.000). Conclusion The bacterial adhesion ability varies upon the difference of IOL materials.Less bacterial adhesion is found on hydrophilic acrylic IOL and HSM-PMMA IOL,implying that the use of IOLs made from these two materials during surgery could diminish the incidence of postoperative endophthalmitis and intraocular inflammation associated with IOLs implantation. Key words: Intraocular lens; Bacterial adhesion; Staphylococcus epidermidis; Endophthalmitis