Biofilm formation on hydrophilic intraocular lens material

PURPOSE: To estimate bacterial biofilm formation on the hydrophilic acrylic (hydrogel) intraocular lens (IOL) Meridian (HP60M, Baush & Lomb) and to investigate a preventive effect against biofilm formation of hydrogel IOLs presoaked in antibiotics. METHODS: Two Staphylococcus epidermidis strains, ATCC 12228 and ATCC 35984 (biofilm-producer), and an Enterococcus faecalis strain (KOS1, clinical isolate from an endophthalmitis patient) were used. Biofilms were cultivated on disks of different IOL materials: hydrogel, PMMA (polymethylmethacrylate), and acrylic. Biofilms were stained with crystal violet (CV), which served as an index of biofilm formation. The bacterial population was enumerated after biofilm homogenization. Biofilms were also examined by scanning electron microscopy (SEM). IOLs were presoaked in two antibiotics, levofloxacin (LVFX) and gatifloxacin (GFLX), and then the bacterial population was enumerated. As in vivo experiment, antibiotics-treated and nontreated Meridian IOLs were implanted in rabbit eyes, which served as an endophthalmitis model, and the bacterial population was enumerated. RESULTS: The amount of biofilm formed was the least on hydrogel from among the three materials tested after 48- and 72-hr incubation (p < 0.05 to 0.01). The bacterial population was the least on hydrogel from among the three materials with ATCC 12228 (p < 0.05 to 0.01), and the bacterial population was significantly different between hydrogel and acrylic after 72-hr incubation with ATCC 35984 (p < 0.05). Biofilm by the two S. epidermidis strains were recognized after 24-hr incubation. Rates of biofilm-positive SEM fields, which were defined as being occupied by biofilm over at least half of the area, were increased through 72 hr with ATCC 35984. While the E. faecalis strain showed no bacterial adherence on the antibiotics-treated hydrogel IOLs, adherence of the S. epidermidis strain, ATCC 35984 was recognized on the LVFX-treated IOLs after 48-hr incubation (103 to 104 CFU/ml). In the rabbit in vivo model, the bacterial populations in eyes with an antibiotics-treated Meridian IOL were significantly smaller than in eyes with a nontreated IOL for 72 hr after surgery (p < 0.05 to 0.01). CONCLUSIONS: The biofilm formation was less on hydrogel than on other two materials tested. Hydrogel presoaked in antibiotics exhibited a preventive effect against biofilm formation at least for 24 hr in vitro and against bacterial proliferation in the rabbit in vivo endophthalmitis model.     

Biofilm formation by Enterococcus faecalis on intraocular lens material

PURPOSE: To compare biofilm formation by Enterococcus faecalis on different intraocular lens (IOL) materials. METHODS: E. faecalis biofilms were cultivated on disks of IOL material (silicone, PMMA [polymethylmethacrylate], or acrylic). Biofilms were stained with crystal violet (CV), which served as an index of biofilm formation. The bacterial population was enumerated after biofilm homogenization. Biofilms were also examined by confocal microscopy. RESULTS: At 24 hr, there was no significant difference in biofilm formation, or the population within biofilms, among the three materials tested. However, after 48 and 72 hr, it was observed that silicone supported the least amount of biofilm formation (p < 0.05); biomass on PMMA and acrylic IOLs continued to increase, with acrylic demonstrating the greatest amount of stainable biofilm (p < 0.0005). The population on PMMA was significantly greater than the other IOL materials (p < 0.005). Confocal microscopy confirmed the lack of biomass on silicone. CONCLUSIONS: Among three IOL materials, E. faecalis biofilms formed more readily on PMMA and acrylic compared to silicone.     

Surface modification of silicone intraocular lens by 2-methacryloyloxyethyl phosphoryl-choline binding to reduce Staphylococcus epidermidis adherence

PURPOSE: To analyse the in vitro adherence of Staphylococcus epidermidis to the 2-methacryloyl oxyethyl phosphorylcholine (MPC)-modified silicone intraocular lens (IOL). METHODS: The test IOLs were modified by using an air plasma treatment to bind MPC to the surface. The control IOLs were not modified. Chemical changes on the IOL surface were analysed by X-ray photoelectron spectroscopy (XPS) to confirm the covalent binding of MPC. IOL hydrophilicity was determined by measuring the water contact angle. Two different techniques, direct counting of viable adherent bacteria released by sonication, and scanning electron microscopy (SEM), were used to observe and compare the adherence of S. epidermidis to the IOLs after 1- and 18-h incubation. RESULTS: XPS analysis confirmed that the test IOLs were surface-modified with MPC. The hydrophilicity of the IOLs was improved by surface modification, and the MPC-modified IOLs exhibited significantly reduced adhesion of S. epidermidis (P = 0.002) after an incubation period of 1 h. The SEM results showed that the MPC modification also suppressed the accumulation of bacteria and biofilm production after 18 h incubation. CONCLUSIONS: MPC-modified hydrophilic silicone IOLs reduce bacterial adherence and colonization, and thus may help reduce the incidence of postoperative endophthalmitis.     

Adherence and kinetics of biofilm formation of Staphylococcus epidermidis to different types of intraocular lenses under dynamic flow conditions

PURPOSE: To compare the adherence and biofilm formation of Staphylococcus epidermidis under in vitro flow conditions on intraocular lenses (IOLs) made of 4 biomaterials: poly(methyl methacrylate) (PMMA), silicone, hydrophilic acrylic, and hydrophobic acrylic. SETTING: Department of Ophthalmology, Croix-Rousse University Hospital and University Research Laboratory, Lyon, France. METHODS: Intraocular lenses were placed in a bioreactor designed to replicate intraocular conditions. The model consisted of Tygon tubing connected to a vial. Three septa allowed the entry and elimination of the artificial aqueous humor and inoculation of the bacterial suspension.The first of 2 pumps moved the aqueous humor along the circuit; the second pump regulated the flow at which the nutritive environment was regenerated. At various times (12, 16, 24, 40, 48, 60, and 72 hours), IOLs were taken from this environment and the bound bacteria were removed and counted. The distribution of bacterial adhesion on the IOLs was modeled using polynomial Poisson regression. To test the effect of the IOL biomaterial on bacterial adhesion, likelihood ratio tests were performed. RESULTS: The model provided the kinetics of S epidermidis biofilm growth on IOLs. The biofilm growth on each of the 4 biomaterials occurred in 3 phases: latent, dynamic or accelerated growth, and linear growth. The extent of bacterial binding to IOLs increased from hydrophilic acrylic polymer to PMMA, hydrophobic acrylic, and silicone. The differences were statistically significant. CONCLUSION: Bacterial adhesion to and biofilm development on the IOL surface depended on the characteristics of the biomaterial.     

不同材料人工晶状体表面表皮葡萄球菌黏附实验的研究

背景感染性眼内炎是白内障摘出及人工晶状体（IOL）植入术后最严重的并发症之一,细菌黏附于IOL表面随手术带人眼内是其主要原因,了解细菌对IOL的黏附情况对预防术后眼内炎的发生具有重要意义。目的研究不同材料的IOL光学表面表皮葡萄球菌的黏附情况,比较细菌培养菌落计数及扫描电子显微镜计数2种方法的优缺点。方法疏水性丙烯酸酯IOL、聚甲基丙烯酸甲酯IOL（PMMAIOL）、肝素修饰聚甲基丙烯酸甲酯（HSM—PMMAIOL）、硅凝胶IOL（SIIOL）、亲水性丙烯酸酯IOL5种不同材料的IOL（每种6枚）置于表皮葡萄球菌（ATCC12228）细菌悬液1h后,采用细菌培养菌落计数及扫描电子显微镜2种方法观察表皮葡萄球菌在各种IOL表面的黏附数量。结果细菌培养菌落计数发现疏水性丙烯酸酯IOL和PMMAIOL最易于黏附细菌,亲水性丙烯酸酯和HSM—PMMAIOL黏附的细菌最少,5种IOL中细菌黏附数的比较差异有统计学意义（F=100．084,P=0．000）,亲水性丙烯酸组和HSM—PMMA组间差异无统计学意义（t=2．285,P=0．052）;扫描电子显微镜观察结果显示5种IOL组细菌在IOL上光学分布表面计数的总体比较差异有统计学意义,按照细菌在IOL上黏附的数量从多到少依次为Hydrophobie〉PMMA〉SI〉Hvdrophilic〉HSM—PMMA（F：118．065,P=0．000）。两种细菌菌落计数方法比较发现扫描电子显微镜法优于细菌培养菌落计数法,差异有统计学意义（t=5．019,P=0．000）。结论5种IOL中以亲水性丙烯酸酯和HSM～PMMAIOL黏附的细菌最少,提示亲水性丙烯酸酯IOL和HSM—PMMAIOL在降低白内障IOL植入术后眼内炎的发生方面有一定的作用。     

In vitro adhesion of Staphylococcus epidermidis to intraocular lenses

PURPOSE: To compare the in vitro adherence of slime-producing and non-slime-producing Staphylococcus epidermidis to different intraocular lenses (IOLs) to study the organism's contribution to postoperative endophthalmitis. METHODS: Strains of slime-positive (ATCC 35984) and slime-negative (ATCC 12228) S epidermidis were used. The IOLs were made of poly(methyl methacrylate) (PMMA), PMMA with polypropylene haptics, silicone, hydrogel, acrylic, heparin-surface-modified (HSM) PMMA, and fluorine-surface-modified PMMA. The lenses were incubated overnight with bacteria, then sonicated and vortexed to separate the adhered bacteria. Quantitative cultures were performed and the results statistically analyzed. RESULTS: Slime-negative strains of S epidermidis adhered to all IOLs but at a lower level than slime-positive strains. The most adherent lenses were acrylic with the positive strain and PMMA with the negative strain. The least adherent IOLs were PMMA with the positive strain and hydrogel with the negative strain. There were no significant differences between rigid and foldable lenses. Polypropylene was significantly more adherent than PMMA to the slime-positive strain. The acrylic and the HSM PMMA IOLs were significantly more adherent to the positive strain. CONCLUSIONS: In vitro, there were significant differences in bacterial adhesion among IOL materials. Slime-positive strains of S epidermidis were more adherent than slime-negative ones.     

不同人工晶状体光学部表面细菌粘附的实验研究

目的:研究比较在丙烯酸酯(acrylic,Acrysof)、硅凝胶(sili-cone,SI)、聚甲基丙烯酸甲酯(polymethylmethacrylate,PM-MA)三种人工晶状体光学表面,表皮葡萄球菌、金黄色葡萄球菌、肠球菌、铜绿假单胞菌的粘附情况。方法:采用扫描电子显微镜方法观察在3种人工晶状体(IOL)光学表面,4种细菌粘附的情况。结果:3种IOL光学表面各种细菌的粘附数量情况,表皮葡萄球菌组:SI>Acrysof>PMMA(P<0.05);金黄色葡萄球菌组:三者差异无显著性;肠球菌组:SI>Acrysof>PM-MA(P<0.05);铜绿假单胞菌组:SI>Acrysof>PMMA(P<0.05)。结论:在研究中发现SI粘附的细菌数明显较Acrysof及PMMA多,这对白内障摘除、人工晶状体植入手术后眼内炎的发生及处理方面有一定参考。     

Effects of surface modification of intraocular lenses on foreign body reaction

PURPOSE: In order to improve biocompatibility, we investigated the effects of surface modification by 2-methacryloyloxyethyl phosphorylcholine (MPC) on the foreign body reaction of intraocular lens (IOLs). MATERIALS AND METHODS: Materials of the IOLs were polymethylmethacrylate, hydrophobic acryl, and MPC surface-modified hydrophobic IOLs (MPC modified acryl). In an in vitro study, cultured macrophages sampled from mouse intra-abdominal exudate were cultured on a plate for each IOL material. The cell density and morphology of attached cells on the IOL materials were investigated. In an in vivo study, each IOL material was implanted in the peritoneal space of mice and foreign body reaction was investigated with a light microscope and a scanning electron microscope. RESULTS: In the in vitro study, the cells on the MPC modified acryl IOL material were remarkably fewer than those on the plates of the other two IOL materials. Regarding the implanted IOL matrevials, MPC modified acryl IOL material showed more polynuclear giant foreign body cells in the early period than the other two IOL materials. CONCLUSION: MPC surface modification can reduce the foreign body reaction of IOLs and has the potential to improve biocompatibility of IOL materials.     

Effect of intraocular lens optic edge design and material on fibrotic capsule opacification and capsulorhexis contraction

PURPOSE: To examine the influence of intraocular lens (IOL) optic edge design and optic material on fibrosis of the anterior and peripheral posterior capsules and on capsulorhexis contraction. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: This randomized controlled patient- and examiner-masked study comprised 210 eyes of 105 patients with bilateral age-related cataract. In Group 1 (n = 53), the Sensar OptiEdge AR40e hydrophobic acrylic IOL with a sharp posterior optic edge was compared with the AR40 acrylic IOL with a round edge. In Group 2 (n = 52), the ClariFlex OptiEdge silicone IOL with a sharp posterior optic edge was compared with the PhacoFlex SI-40 silicone IOL with a round edge All IOLs were manufactured by Advanced Medical Optics, Inc. Standardized digital slitlamp images of anterior capsule opacification (ACO) and fibrotic posterior capsule opacification (PCO) were taken 1 year postoperatively, and digital retroillumination images were taken at 1 week and 1 year. The intensity of fibrotic PCO was graded subjectively (score 0 to 4), ACO was graded objectively (score 0% to 100%), and the capsulorhexis area (mm(2)) was determined objectively. RESULTS: One year after surgery, the mean ACO score was 32% in eyes with the sharp-edged acrylic IOL and 29% in eyes with the round-edged acrylic IOL (P<.05). In the silicone group, the mean was 31% and 26%, respectively (P<.05). The mean fibrotic PCO score was lower in eyes with a sharp-edged acrylic IOL than in eyes with a round-edged acrylic IOL (0.26 and 0.93, respectively; P<.05) and in eyes with a sharp-edged silicone IOL than in eyes with a round-edged silicone IOL (0.24 and 0.82, respectively; P<.001). At 1 year, the mean capsulorhexis area was statistically significantly smaller in eyes with a sharp-edged silicone IOL than in eyes with a round-edged silicone IOL (P<.05). CONCLUSIONS: Acrylic and silicone IOLs with the sharp OptiEdge design led to significantly less fibrotic PCO but more ACO than round-edged acrylic and silicone IOLs. The sharp-edged silicone IOL caused significantly more capsulorhexis contraction than the round-edged silicone IOL and both acrylic IOLs.     

In vivo study of bacterial adhesion to five types of intraocular lenses

PURPOSE: To determine in vivo behavior of the ability of the Staphylococcus epidermidis strain (American Type Culture Collection [ATCC] 14990) to attach to 120 intraocular lenses (IOLs) made of five different biomaterials: fluorine polymethylmethacrylate (PMMA), heparinized PMMA, silicone, hydrophobic acrylic, and hydrogel. The pig was chosen as an animal model of endophthalmitis, after a bibliographical analysis and a personal study of its aqueous humor composition. METHODS: Crystalline lenses from 90 domestic pigs were removed aseptically and replaced with previously infected IOLs. The animals were killed 24 hours, 72 hours, and 1 week after implantation of the IOLs. The extent of bacterial binding was then measured by counting. Results were compared with a two-factor analysis of variance (ANOVA 2), confirmed by the Kruskal-Wallis nonparametric test. RESULTS: The extent of bacterial binding (expressed as bound bacteria per area unit) was found to range in increasing order from hydrogel, to fluorine PMMA, to hydrophobic acrylic, to heparinized PMMA, to silicone polymer. Comparison of pairs of materials showed statistically significant differences, except between hydrogel and fluorine PMMA. CONCLUSIONS: To the authors' knowledge, no study has been published so far concerning the in vivo evolution of populations of bacteria adhering to different intraocular materials. Bacterial adhesion to the implant surface must therefore depend on the hydrophobicity or hydrophilicity of the biomaterial. Adhesion is also affected by the nature of the surrounding medium. Because of its complexity, the latter appears to be very difficult to model, thus making in vivo studies essential.     

Corneal edema and permanent blue discoloration of a silicone intraocular lens by methylene blue.

BACKGROUND AND OBJECTIVE: To report a silicone intraocular lens (IOL) stained blue by inadvertent intraoperative use of methylene blue instead of trypan blue and the results of experimental staining of various lens materials with different concentrations of the same dye. MATERIALS AND METHODS: A "blue dye" was used to enhance visualization during capsulorhexis in a patient undergoing phacoemulsification with implantation of a three-piece silicone lens. Postoperatively, the patient presented with corneal edema and a discolored IOL. Various IOL materials were experimentally stained using methylene blue. Sixteen lenses (4 silicone, 4 hydrophobic acrylic, 4 hydrophilic acrylic, and 4 polymethylmethacrylate) were immersed in 0.5 mL of methylene blue at concentrations of 1%, 0.1%, 0.01%, and 0.001%. These lenses were grossly and microscopically evaluated for discoloration 6 and 24 hours after immersion. RESULTS: The corneal edema resolved within 1 month after the initial surgical procedure. After explantation, gross and microscopic analyses of the explanted silicone lens revealed that its surface and internal substance had been permanently stained blue. In the experimental study, all of the lenses except the polymethylmethacrylate lenses were permanently stained by methylene blue. The hydrophilic acrylic lenses showed the most intense blue staining in all dye concentrations. CONCLUSIONS: This is the first clinicopathological report of IOL discoloration due to intraocular use of methylene blue. This and other tissue dyes may be commonly found among surgical supplies in the operating room and due diligence is necessary to avoid mistaking these dyes for those commonly used during ocular surgery.     

Analysis of intraocular lens surface properties with atomic force microscopy

PURPOSE: To analyze the surface optics of 4 currently available intraocular lenses (IOLs) with atomic force microscopy. SETTING: Licryl Laboratory, University of Calabria, Rende, Italy. METHODS: The surface roughness and topography of poly(methyl methacrylate) (PMMA), silicone, hydrophobic, and hydrophilic acrylic IOLs were evaluated with atomic force microscopy in contact mode. The analysis was performed in a liquid environment using cantilevers with a 0.01 Newtonw/meter nominal elastic constant. Measurements were made over areas of 10 microm2 on different locations of the posterior optic surface of the IOL. RESULTS: Atomic force microscopy permitted high-resolution imaging of IOL optic surface characteristics. Surface topography showed different features with respect to the lens biomaterial. The root-mean-square roughness of the IOL optic surface was significantly different between lenses of various materials (P < .001). The hydrophobic acrylic and silicone IOLs had the lowest mean surface roughness, 3.8 nm +/- 0.2 (SD) and 4.0 +/- 0.5 nm, respectively, and the 2 PMMA IOLs had the highest mean surface roughness, 6.6 +/- 0.3 nm and 7.0 +/- 0.6 nm. CONCLUSIONS: Atomic force microscopy was effective and accurate in analyzing IOL optics. The surface topography of IOLs may vary with different manufacturing processes.     

青光眼白内障联合术植入不同材料人工晶状体效果评价

目的比较青光眼白内障联合术中植入不同材料人工晶状体（IOL）的临床效果。方法回顾性分析行青光眼白内障联合术70例（76眼），其中植入PMMA IOL30例（36眼），硅胶IOL23例（23眼），丙烯酸酯折叠IOL17例（17眼）。对治疗效果进行评价，平均随访期限为10．5月。结果3组间术后眼压和最佳矫正视力差异无统计学意义。前房纤维素样渗出物和IOL表面沉积物发生率，硅胶组高于PMMA组和丙烯酸酯组，但差异无统计学意义。后发障发生率，丙烯酸酯组和硅胶组显著低于PMMA组，差异有统计学意义。结论行青光眼白内障联合术植入PMMA，硅胶与丙烯酸酯IOL在降眼压和提高视力方面具有相似的效果。但硅胶IOL的前房纤维素样渗出物及IOL表面沉积物发生率高于PMMA和丙烯酸酯IOL。丙烯酸酯和硅胶IOL的后发障发生率低于PMMA IOL。     

Elapsed time for capsular apposition to intraocular lens after cataract surgery

OBJECTIVE: To examine when the anterior and posterior lens capsule completely become apposed to optics of silicone and acrylic intraocular lenses (IOLs) implanted after cataract surgery and to determine whether the different IOL materials influence the timing of completion of capsular contact. DESIGN: Randomized controlled clinical trial. PARTICIPANTS: Seventy eyes of 70 patients who were scheduled to undergo cataract surgery were randomly assigned to two groups using random number tables based on the type of IOL implanted: silicone or acrylic. Thirty-two patients in each group completed the follow-up. INTERVENTION: All eyes underwent phacoemulsification surgery with implantation of either a silicone or acrylic IOL. All IOLs were accurately placed into the capsular bag. MAIN OUTCOME MEASURES: Contact of the anterior and posterior lens capsule with the IOL optic surface was evaluated using the Scheimpflug videophotography system at 3, 5, 7, 9, 11, 14, 21, and 28 days after surgery. The postoperative day at which each capsule was completely apposed to the IOL optic was determined. In addition, anterior chamber depth was also measured. RESULTS: The anterior capsule was in contact with the IOL optic on the same day or earlier than the posterior capsule in all patients. Complete apposition of the IOL was observed significantly earlier with silicone IOLs than with acrylic IOLs with both the anterior capsule (6.2 versus 3.6 postoperative days; P < 0.0001) and the posterior capsule (11.1 versus 7.4 postoperative days; P = 0.0339). No significant change in mean anterior chamber depth was observed with the silicone IOL, whereas there was significant anterior shift after implantation of the acrylic IOL. CONCLUSIONS: Capsular contact with the IOL optic is completed within approximately 8 days after cataract surgery with silicone IOLs and 11 days with acrylic IOLs. Complete apposition to both the anterior and posterior capsule was significantly earlier with silicone IOLs than with acrylic IOLs.     

Limitation of Scheimpflug videophotography system in quantifying posterior capsule opacification after intraocular lens implantation

PURPOSE: To assess the applicability of Scheimpflug videophotography system for the quantitative comparison of posterior capsule opacification after intraocular lens (IOL) implantation of different materials. DESIGN: Retrospective, nonrandomized, interventional case series. METHODS: Three groups (n = 15 eyes, each) underwent cataract surgery with implantation of acrylic, silicone, or hydrogel IOL. One year after surgery, the scatter light density at the anterior IOL surface level was measured using EAS-1000. Another three groups (n = 32 eyes, each) received acrylic, silicone, or hydrogel lens. One week after surgery, the scatter light density at the posterior capsule was measured. RESULTS: Scatter light density at the anterior IOL surface 1 year after implantation was 7.5 +/- 3.0 computer-compatible tape (CCT) steps in the acrylic group, 6.0 +/- 2.3 CCT steps in the silicone group, and 5.0 +/- 3.2 CCT steps in the hydrogel group; the density in the acrylic group was significantly greater than that in the hydrogel group (P =.026). Scatter light density at the posterior capsule level 1 week after surgery was 28.3 +/- 8.9 CCT steps in the acrylic group, 22.2 +/- 2.0 CCT steps in the silicone group, and 26.7 +/- 6.7 CCT steps in the hydrogel group; there was a significant difference between the acrylic and silicone groups (P =.0005) and between the silicone and hydrogel groups (P =.008). CONCLUSIONS: The IOL material significantly influences the scatter light density measurements of Scheimpflug videophotography system, and thus the intensity of posterior capsule opacification quantified by this system cannot be directly compared with different optic materials.     

Comparison of glistenings in intraocular lenses with three different materials: 12‐year follow‐up

Purpose: To compare the degree of lens glistenings associated with three intraocular lenses (IOLs) of different materials and examine the relationship between the dioptric power of the optics and lens glistenings in a long‐term study. Setting: St. Erik Eye Hospital, Stockholm, Sweden. Methods: Forty‐six eyes of 46 patients underwent standard phacoemulsification and implantation with a heparin‐surface‐modified (HSM) polymethylmethacrylate (PMMA) IOL, a silicone IOL or a hydrophobic acrylic IOL. Evaluations of the patients and the glistenings were conducted 11.3–13.4 years postoperatively. The glistenings were examined using Scheimpflug imaging and subsequently analysed using an image analysis program. Results: The median follow‐up time was 12.2 years (range, 11.3–13.4). The hydrophobic acrylic IOL had significantly more lens glistenings than the silicone (p = 0.003) and the PMMA (p = 0.000) IOLs. The silicone IOL had significantly more lens glistenings than the PMMA lens (p = 0.048). The IOL power did not affect the degree of lens glistenings in the hydrophobic acrylic IOL group (p = 0.64). The other groups had too little lens glistenings to evaluate the relationship. Conclusion: In this long‐term follow‐up study, the hydrophobic acrylic IOL had a significantly higher degree of lens glistenings compared to the silicone and PMMA IOLs. The PMMA IOL had almost no lens glistenings. The IOL dioptric power was not significantly correlated with the degree of lens glistenings associated with the hydrophobic acrylic IOL.     

Chemoattraction of inflammatory cells by various intraocular lens materials

PURPOSE: To compare the chemotactic activity induced by polymethyl methacrylate (PMMA), acrylic, and silicone intraocular lens (IOL) materials, regardless of the surgical and host factors. METHODS: The chemotactic effect of five different IOLs was studied using a modified multi-well Boyden chamber. Two different non-coated PMMA IOLs, a heparin-coated PMMA IOL, an acrylic IOL, and a silicone IOL were assessed. Each mean migration distance of the IOLs was compared with the others using Student's t test. RESULTS: All IOLs induced some amount of leukocyte chemotaxis. There was no statistically significant difference between the chemotactic activity of PMMA IOLs. However, chemotactic activity was significantly higher in acrylic (p<0.05) and silicone (p<0.05) IOLs compared to one of the PMMA lenses. CONCLUSIONS: This limited study has proven that chemotaxis assay is a useful tool to assess the biocompatibility of IOLs. The IOL material itself might attract inflammatory cells to its surface in the absence of surgical and host factors. As PMMA IOLs do not cause an increase in inflammatory reaction, they may be considered safe to use. Further improvement in chemical composition and surface characteristics of IOLs should reduce the inflammatory reaction and increase the biocompatibility and safety of IOLs.     

Adhesion mechanisms of human lens epithelial cells on 4 intraocular lens materials

PURPOSE: To evaluate lens epithelial cell (LEC) adhesion on different intraocular lens (IOL) materials with particular attention to the distribution of proteins located in the focal contacts. SETTING: Center of Biotechnological and Clinical Research in Ophthalmology, University of Bologna, Italy. METHODS: The IOL materials tested were poly(methyl methacrylate) (PMMA), heparin-surface-modified PMMA (HSM PMMA), polyHEMA, and silicone. Primary cultures of human LECs were established from human anterior capsules obtained during cataract surgery. The mean number of cells attached per square millimeter was calculated for each material after 24 and 72 hours. Transmission electron microscopy and immunocytochemical analysis were performed to detect the proteins actin, vinculin, and talin. RESULTS: Mean adhesiveness of human LECs increased over time with PMMA and decreased with the other materials. At 72 hours, mean LECs ranged from 54.8 cells/mm2 +/- 12.8 (SD) on PMMA to 2.1 +/- 0.7 cells/mm2 on silicone. The means for HSM PMMA and polyHEMA fell in between. The cytoskeletal proteins were arranged to produce focal contacts in only the LECs cultured on PMMA. The LECs cultured on polyHEMA, HSM PMMA, and silicone attached but failed to develop focal contacts or stress fibers. CONCLUSION: This study confirms the multifactorial pathogenesis of posterior capsule opacification and suggests its incidence will be reduced by improving surgical techniques and using IOL surfaces that discourage cell adhesion.     

Posterior capsule opacification: comparison of 3 intraocular lenses of different materials and design

PURPOSE: To compare posterior capsule opacification (PCO) after cataract surgery with implantation of 3 intraocular lenses (IOLs) of different materials and design. SETTING: St. Erik's Eye Hospital, Stockholm, Sweden. METHODS: In this prospective clinical study, 180 patients had standardized phacoemulsification performed by a single surgeon and were randomized to have implantation of a heparin-surface-modified (HSM) poly(methyl methacrylate) (PMMA) IOL (809C, Pharmacia & Upjohn), a silicone IOL (SI-40NB, Allergan), or an acrylic IOL (AcrySof MA60BM, Alcon). To morphologically evaluate PCO, retroillumination photographs were obtained and analyzed using Evaluation of Posterior Capsule Opacification computer software. The neodymium:YAG (Nd:YAG) capsulotomy rate was recorded. RESULTS: After 2 years, the HSM PMMA IOL group had significantly more PCO than the silicone and AcrySof IOL groups; the silicone group had significantly more PCO than the AcrySof group (P<.05). The Nd:YAG capsulotomy rate was 20% in the HSM PMMA group, 22% in the silicone group, and 8% in the AcrySof group. CONCLUSION: Patients with an AcrySof IOL developed significantly less PCO than those with a silicone or HSM PMMA IOL with a round-edged design.     

Interaction with intraocular lens materials: Does heavy silicone oil act like silicone oil?

PURPOSE: To determine the interaction of heavy silicone oil with various intraocular lens (IOL) materials and whether heavy silicone oil covers the silicone IOL optic as silicone oil does. SETTING: Department of Ophthalmology, Dokuz Eylul University, Izmir, Turkey. METHODS: The study group comprised 5 poly(methyl methacrylate) (PMMA) IOLs, 4 foldable silicone IOLs, 5 foldable hydrophilic acrylic IOLs, and 5 foldable hydrophobic acrylic IOLs. Each IOL was bathed in balanced salt solution (BSS) for 10 minutes and then placed in heavy silicone oil dyed with Sudan Black for another 10 minutes. Afterward, each IOL was reimmersed in BSS for 5 minutes and examined under the light microscope. Digital images were analyzed to determine the optic area covered with heavy silicone oil. RESULTS: The mean heavy silicone oil coverage was 7.05% +/- 7.88% (SD) (range 1.13% to 20.54%) on PMMA IOLs, 100% on silicone IOLs, 12.17% +/- 11.43% (range 1.25% to 31.52%) on hydrophobic acrylic IOLs, and 34.64% +/- 13.28% (range 12.57% to 44.42%) on hydrophilic acrylic IOLs. Heavy silicone oil coverage of silicone IOLs was statistically significantly greater than the coverage of other IOL materials. CONCLUSION: Heavy silicone oil acted the same as silicone oil and covered the entire surface of silicone IOLs.