Comparison Of In Vitro Bacterial Adherence To Rigid Contact Lenses Of Different Materials And To The Contact Lenses With And Without Plasma Surface Treatment

ObjectiveTo observe the in vitro adherence ability of different bacteria （staphylococcus aureus,staphylococcus epidermidis and pseudomonas aeruginosa） to different rigid contact lenses（hexafoconA, enflufocon B and polymethyl methacrylate）.MethodsContact lenses were placed in bacterial suspension （0.5McF）.. Bacteria binding wasmeasured and analyzed by Methyl thiazolyl tetrazolium （MTT） assay, Spiraloscillation-bacterial culture quantitative method and scanning electron microscopy （SEM）.ResultsMTT assay: Adherence of staphylococcus aureus to XO was significant lower than toEO and PMMA （q=7.379，q=8.207, P<0.01）, no significant difference were found betweenEO and PMMA （q=0.828，P>0.05）. Adherence of staphylococcus epidermidis to XO and toEO was lower than to PMMA （q=14，q=12.8，P<0.01）, yet no significant differencebetween XO and EO （q=1.2，P>0.05）. There was no difference of pseudomonas aeruginosaadherence to all three kinds of contact lens （F=2.155, P>0.05）.Spiral oscillation-bacterial culture quantitative methods: Adherence of staphylococcusaureus to XO was higher than to EO, while to PMMA was the highest （q=11.65, q=28.64,q=16.99, P<0.01）. Adherence of staphylococcus epidermidis to XO was significantly lowerthan to PMMA （q=5.06, P<0.05）, no significant difference was found either between XOand EO or between EO and PMMA （q=3.29, q=1.77, P>0.05）. As for pseudomonas aeruginosa, no difference was found among the three contact lens （F=0.232, P>0.05）.SEM: Adherence of staphylococcus aureus and staphylococcus epidermidis was lowto both XO and EO, and the bacterial colonization distributed dispersedly. Yet bacterialadhesions of Staphylococcus aureus and staphylococcus epidermidis to PMAA wereapparent, and the colonization connected with each other to form a network. Bacterialattachments of pseudomonas aeruginosa were apparent to all of the three contact lens, andno significant difference among the three lens, both morphologically and quantitatively.ConclusionsIn vitro bacterial adherence to PMMA is higher than to XO and to EO. Theimprovement of gas-permeability of rigid contact lens might not increase in vitro bacterialadhesion. ObjectiveTo observe the influence of plasma surface treatment on adherence of staphylococcusaureus and pseudomonas aeruginosa to hexafocon （XO, XO₂）.MethodsPlasma treatment were conducted to XO and XO₂to obtain XO-P and XO₂-Prespectively. The four rigid contact lenses were placed into bacteria suspension （0.5McF）.We took XO and XO₂as control in this study. Bacteria binding was measured by Methylassay, Spiral oscillation-bacterial culture quantitative method and SEM.ResultsMTT assay shown the OD value of staphylococcus aureus suspension of XO-P was lower than XO, while XO₂-P lower than XO₂（t=20.059, t=27.654, P<0.01）. As forpseudomonas aeruginosa suspension, OD value of XO-P was lower than XO （t=5.426,P<0.01）, yet there was no difference between XO₂-P and XO₂（t=1.480, P>0.05）. Spiraloscillation-bacterial culture quantitative methods showed that the OD value ofstaphylococcus aureus of XO-P was lower than XO, as XO₂-P was lower than XO₂（t=9.786,t=7.547, P<0.01）. The OD value of pseudomonas aeruginosa of XO-P was lower than XO（t=3.185, P<0.01）, and no significant difference was found between XO₂-P and XO₂（t=1.485, P>0.05）. SEM showed that adhesion of staphylococcus aureus to XO-P andXO₂-P distributed dispersedly yet densely to XO and XO₂. Attachment of pseudomonasaeruginosa to XO-P and to XO₂-P were low， but distributed on XO and XO₂amembrane-like shape.ConclusionsXO-P and XO₂-P are effectively to reduce surface adhesion of staphylococcus aureus.But had no effect on the adhesion of XO₂-P of Pseudomonas aeruginosa. ObjectiveTo investigate status of bacterial flora in conjunctival sac of adolescents wearingorthokeratology and in their storage cases.Methods101adolescents wearing orthokeratology （wearing group） and110adolescents who do not wear （control group） were involved in our survey. Samples collected fromconjunctival sac and storage cases were cultured at37℃for48h.Results59strains of bacteria were cultured in wearing group, with a positive rate29.35%. Incontrol group,68strains were found, and the positive rate is30.90%. There was nosignificant difference between the two groups （χ²=0.12, P>0.05）.72strains of bacteriawere cultured in the orthokeratology lens storage cases, with a positive rate45.56%. Thetop three strains of bacteria in all of the three sources were basically the same, includingStaphylococcus epidermidis, Staphylococcus aureus and Corynebacterium.ConclusionsWearing orthokeratology lens did not significantly increased positive rate of bacterialflora. Simultaneously, it’s effective to reduce lens pollution rate by cleaning lens and cases.