Differential responses of human lens epithelial cells to intraocular lenses in vitro: hydrophobic acrylic versus PMMA or silicone discs

Background The purpose of this study was to determine the influence of different materials of intraocular lenses (IOLs) on human lens epithelial cell behavior, including adhesion, migration, proliferation, apoptosis, and epithelial-mesenchymal transdifferentiation (EMT) in vitro. Methods Human lens epithelial cells (SRA 01/04) were grown on hydrophobic acrylic (Acrysof), polymethylmethacrylate (PMMA), and silicone IOLs. Cellular adhesion, migration, proliferation, and apoptotic assays were performed to assess cell behavior. The expression of EMT markers (fibronectin and type I collagen) produced by cells on IOLs was determined by immunoblotting and immunocytochemistry. Results Human lens epithelial cells exhibited preferred adhesion and reduced apoptosis when cultured on acrylic IOLs, in comparison to PMMA and silicone IOLs. Cells grown on acrylic lenses formed a confluent epithelial monolayer. Migration of lens epithelial cells under the acrylic lens was substantially blocked in an in vitro assay. In contrast, cells grown on PMMA and silicone lenses displayed a spindle-shaped, myofibroblast-like morphology, increased apoptosis, reduced adhesion, and enhanced production of EMT proteins such as fibronectin and type I collagen. The migration of lens epithelial cells under PMMA and silicone IOLs was substantial in the in vitro assay. Conclusion This report demonstrates that hydrophobic acrylic lenses are more capsular biocompatible than PMMA and silicone lenses. The in vitro assays are reliable measurements for evaluating the responses of human lens epithelial cells to different IOL materials, and could advance our understanding of the preferential capsular opacification conferred by different IOL materials.     

Adhesion of lens capsule to intraocular lenses of polymethylmethacrylate, silicone, and acrylic foldable materials: an experimental study

AIMS—To investigate the adhesion characteristics of several intraocular lenses (IOLs) to the simulated and rabbit lens capsule.
METHODS—Adhesive force to bovine collagen sheets was measured in water with polymethylmethacrylate (PMMA), three piece silicone, and acrylic foldable IOLs. In rabbit eyes, phacoemulsification and IOL implantation were performed. Three weeks later, adhesion between the anterior/posterior capsules and IOL optic was tested, and the capsule was examined histologically.
RESULTS—The mean adhesive force to the collagen sheet was 1697 (SD 286) mg for acrylic foldable, 583 (49) mg for PMMA, and 0 mg for silicone IOLs (p=0.0003, Kruskal-Wallis test). Scores (0-5) of adhesion between rabbit anterior capsule and IOL optic were 4.50 (0.55) for acrylic foldable, 3.20 (0.84) for PMMA, and 0.40 (0.55) for silicone IOLs (p=0.004). Scores between rabbit posterior capsule and IOL optic displayed a similar tendency; 4.50 (0.84) for acrylic foldable, 3.00 (1.00) for PMMA, and 0.40 (0.55) for silicone IOLs (p=0.021). Histological observation indicated that the edge of IOL optic suppressed the migration of lens epithelial cells towards the centre of the posterior capsule. This inhibitory effect was most pronounced with acrylic foldable IOL and least with silicone IOL.
CONCLUSIONS—The acrylic foldable IOL adhered to the lens capsule more than the PMMA IOL, and the silicone IOL showed no adhesiveness. These differences seem to play a role in preventing lens epithelial cells from migrating and forming posterior capsule opacification.

Keywords: intraocular lens; lens capsule; posterior capsule opacification; adhesion     

Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 2: explanted intraocular lenses

PURPOSE: To evaluate fibronectin, vitronectin, laminin, and collagen type IV adhesion to poly(methyl methacrylate) (PMMA), silicone, hydrophobic soft acrylate, and hydrogel intraocular lenses (IOLs) in human pseudophakic autopsy eyes. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Thirty-two autopsy eyes containing PMMA, silicone, soft acrylate, or hydrogel IOLs were assessed. The IOLs were explanted from the capsular bag, and both sides of the IOLs were immunohistochemically stained for fibronectin, vitronectin, laminin, or collagen type IV. The number of cells on the IOL surfaces was counted. The capsular bag from 1 eye containing a soft acrylate IOL was examined for fibronectin and vitronectin. RESULTS: Hydrophobic soft acrylate IOLs had significantly more fibronectin adhering to their surfaces than PMMA (P <.01) or silicone (P <.01) IOLs, as well as more vitronectin. Silicone IOLs had more collagen type IV adhesion than the other IOLs (P <.05-.06). Collective protein adhesion differed significantly between soft acrylate IOLs and PMMA and silicone IOLs, but not between PMMA and silicone IOLs. CONCLUSIONS: The greater amount of protein on the hydrophobic soft acrylate (AcrySof(R)) IOLs seems to support an adhesive mechanism for their attachment to the capsular bag. Fibronectin and vitronectin have functional domains to bind them to lens epithelial cells and the collagenous capsule. This kind of attachment could be a true bioactive bond and may be 1 reason the PCO and neodymium:YAG capsulotomy rates are lower in eyes with a soft acrylate IOL.     

Drug interaction with intraocular lenses of different materials.

The uptake and washout kinetics of four drugs representing different classes of ophthalmic medications were measured in intraocular lenses of different materials. The materials ranged from hydrogel lenses to poly(methyl methacrylate) (PMMA), Acrysof (acrylic/methacrylic), and two types of silicone lenses (Chiroflex and AMO SI-18NB). Uptake was determined after seven days of immersion in a large volume of Ringer's solution containing drug concentrations that equaled those found in aqueous humor 30 minutes to one hour after topical administration. Washout was determined after placing lenses in 1 ml of 0.9% saline for 24 hours. Only hydrogel lenses could be digested in acid to measure lens uptake directly. The PMMA, Acrysof, and silicone lenses behaved similarly toward gentamicin and dexamethasone--low uptake (less than 3.5 ng/mg lens) and low washout (less than 4.0%). Their uptake of norepinephrine was lower (less than 0.7 ng/mg lens) but the washout varied from 29% (AMO silicone) to 100% (PMMA and Acrysof). The pilocarpine uptake was the lowest of drugs tested (less than 0.03 ng/mg lens) and the washout varied from 1.5% (acrylic) to 100% (PMMA and Chiroflex silicone). Hydrogel lenses took up the most drug in the following order: dexamethasone greater than pilocarpine greater than gentamicin greater than norepinephrine. Washout was high, ranging from 83% to 98%. Despite the greater uptake and washout, the maximum drug uptake would only provide one-tenth of the greatest aqueous humor concentration that occurs after topical drug administration. Intraocular lenses of the materials tested did not interfere with the intraocular drug pharmacokinetics, nor did the data indicate that presoaking intraocular lenses of these materials in drugs would enhance post-surgical intraocular drug concentrations.     

Ultrasound biomicroscopy characterization of acrylic, silicone, and polymethyl methacrylate lenses in vitro

Background: This study aims to characterize the reflective properties of some commonly used intraocular lenses (IOLs) in vitro, with a particular focus on lens haptics.Methods: Six different types of IOLs, representative of silicone, acrylic, and polymethyl methacrylate (PMMA), single, multipiece, and multifocal were imaged using high-resolution ultrasound biomicroscopy (UBM).Results: Reflectivity patterns were distinct to the material that was being imaged irrespective of whether the part being imaged was the haptic or optic. Acrylic haptics demonstrated a single “tram-track” reduplication echo, whereas PMMA haptics showed multiple reverberation echoes off the posterior surface. The optics of various PMMA and acrylic lenses demonstrated a reflectivity pattern similar to the respective haptics made of the same material. Silicone optics displayed clear delineation with no reverberation. Both acrylic and silicone material was relatively less reflective when compared with PMMA.Interpretation: With UBM imaging, the haptics of acrylic and PMMA IOLs demonstrate unique reflective patterns, depending on the material being studied. Prior knowledge of what the lens haptics and optics look like in vitro provides information that may assist in identifying and localizing misplaced intraocular lenses in vivo.     

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。     

Adhesion of fibronectin, vitronectin, laminin, and collagen type IV to intraocular lens materials in pseudophakic human autopsy eyes. Part 1: histological sections

PURPOSE: To evaluate fibronectin, vitronectin, laminin, and collagen type IV adhesion to poly(methyl methacrylate) (PMMA), silicone, hydrophobic soft acrylate, and hydrogel intraocular lenses (IOLs) in pseudophakic human autopsy eyes. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Thirty-eight autopsy eyes containing PMMA, silicone, hydrophobic acrylate, or hydrogel IOLs were assessed. Histological sections were prepared from each eye, and immunohistochemical analyses were performed for fibronectin, vitronectin, laminin, and collagen type IV. One hundred fifty-two specimens were analyzed. RESULTS: A sandwich-like structure (anterior or posterior capsule/fibronectin/1 cell layer/fibronectin/IOL surface) was seen in 12 of 14 autopsy eyes with soft acrylate IOLs, 3 of 10 with a PMMA IOL (P =.0094), 1 of 10 with a silicone IOL (P =.0022), and 0 of 4 with a hydrogel IOL (P =. 0041). The thicker fibrocellular tissue on the inner surface of the anterior or posterior capsule that was in contact with silicone IOLs was lined with collagen type IV. Vitronectin and laminin were not found at the fibrocellular tissue-IOL interface in any specimen. CONCLUSIONS: This study seems to confirm the sandwich theory of posterior capsule opacification in eyes with an IOL and suggests that fibronectin may be the major extracellular protein responsible for the attachment of hydrophobic soft acrylate (AcrySof(R)) IOLs to the capsular bag. This may represent a true bioactive bond between the IOL and lens epithelial cells or between the IOL and the capsular bag and may be one reason the PCO and neodymium:YAG capsulotomy rates are lower in eyes with a soft acrylate IOL.     

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.     

Anterior capsule opacification: correlation of pathologic findings with clinical sequelae

OBJECTIVE: To evaluate the degree of anterior capsule opacification (ACO) in human eyes obtained postmortem containing various rigid and foldable posterior chamber intraocular lens (PC-IOL) designs and compare the findings with clinical sequelae of capsular shrinkage. DESIGN: Comparative autopsy tissue study with clinicopathologic correlations. MATERIALS: Three hundred formalin-fixed human eyes containing the following PC-IOL styles were analyzed: (1) one-piece polymethyl methacrylate (PMMA) optic-PMMA haptic (n = 50), one-piece silicone-plate IOL, with large (2) or small (3) fixation holes (n = 35), (4) three-piece PMMA optic-Prolene haptic (n = 50), (5) three-piece acrylic optic-PMMA haptic (n = 55), three-piece silicone optic with PMMA (6) or polyimide (7) haptics (n = 30), and (8) three-piece silicone optic-Prolene haptic (n = 80) lenses. TESTING: The eyes were sectioned in the equatorial plane for gross examination of the capsular bag from a posterior view. The cornea and iris were then excised for evaluation from an anterior view. MAIN OUTCOME MEASURES: ACO was scored in each eye from 0 to IV, according to the degree/area of capsule opacification. Capsulorrhexis size and IOL decentration were measured with calipers. RESULTS: The overall differences among the IOL groups regarding the three parameters were significant (ACO score: P < 0.001; capsulorrhexis diameter: P = 0.036; IOL decentration: P = 0.012). Mean ACO scores were highest with the large- and small-hole one-piece silicone-plate lenses (2.543 +/- 0.950) and lowest with the three-piece acrylic optic-PMMA haptic lenses (0.600 +/- 0.710). Of 10 cases of capsulorrhexis phimosis observed in the study, 7 cases were associated with three-piece silicone optic-Prolene haptic lenses, which also presented the highest mean decentration (0.375 +/- 0.601 mm). CONCLUSIONS: Our results confirm previous histopathologic observations that the rate of ACO is the lowest with acrylic lenses and higher with plate-haptic silicone IOLs. Nevertheless, clinical sequelae of capsular shrinkage are also very important with three-piece silicone optic-Prolene haptic designs. Thus, IOL material and design are significant factors in the development of ACO, but they ultimately also influence the clinical presentation of capsular shrinkage.     

三种不同材料人工晶状体的囊膜生物相容性比较

背景 研究表明,后囊膜混浊(PCO)的发生与人工晶状体(IOLs)的材料有关,然而不同材料的IOLs对PCO发生率的影响存在争议. 目的 研究不同材料IOLs表面人晶状体上皮细胞(LECs)的黏附、增生、上皮-间充质转化(EMT)和相关细胞因子分泌情况,探讨不同材料IOLs的囊膜生物相容性.方法 将人LECs系HLE-B3细胞分别接种于疏水性丙烯酸酯(Acrysof SA60AT) IOLs、硅凝胶(Crystalens) IOLs、聚甲基丙烯酸甲酯(PMMA) IOLs的表面培养6h和24 h,观察不同IOLs表面黏附的细胞数目及其形态;采用细胞计数试剂盒-8(CCK-8)检测IOLs表面细胞的增生反应;采用免疫荧光技术检测不同IOLs表面人LECs间质细胞标志物d-平滑肌肌动蛋白(o-SMA)的表达,计算IOLs表面人LECs的EMT转化率;采用ELISA法检测不同材料IOLs表面细胞培养液中转化生长因子-β2(TGF-β2)、白细胞介素-6(IL-6)、基质金属蛋白酶-2(MMP-2)及MMP-9的质量浓度. 结果 细胞接种于不同材料IOLs并培养6h,Acrysof IOLs和Crystalens IOLs表面黏附的细胞以多边形和椭圆形为主,而PMMA IOLs表面黏附的细胞形态以纺锤形为主;培养后24 h,IOLs表面细胞全部伸展,Acrysof IOLs和Crystalens IOLs表面黏附的细胞为多边形,长梭形细胞增多,PMMA IOLs表面细胞呈典型的纤维纺锤样细胞,部分细胞聚集成团.培养后24 h Acrysof IOLs、Crystalens IOLs和PMMA IOLs表面的增生相对细胞数A值分别为0.238 4±0.007 1、0.178 1±0.0066和0.158 9±0.0069,总体比较差异均有统计学意义(F=475.947,P=0.000),其中Acrysof IOLs表面的细胞数明显多于Crystalens IOLs和PMMAIOLs,差异均有统计学意义(均P＜0.001).Acrysof IOLs、Crystalens IOLs和PMMA IOLs表面人LECs的EMT转化率分别为(9.99±3.80)％、(17.33±5.71)％和(84.16±10.48)％,组间总体比较差异有统计学意义(F=127.411,P=0.000),其中PMMA IOLs表面人LECs的转化率明显高于Crystalens IOLs和Acrysof IOLs,差异均有统计学意义(均P＜0.001).ELISA检测结果显示,Acrysof IOLs、Crystalens IOLs和PMMA IOLs细胞培养液中TGF-β2、IL-6、MMP-2和MMP-9质量浓度的比较差异均无统计学意义(F=0.846、0.947、0.255、0.922,均P＞0.05). 结论 在临床上常用的3种材料的IOLs中,疏水性丙烯酸酯的囊膜生物相容性最佳.     

Effect of heparin surface modification in reducing silicone oil adherence to various intraocular lenses.

PURPOSE: To evaluate surface properties of various intraocular lenses (IOLs), including a newly fabricated heparin-surface-modified (HSM) silicone IOL, with special reference to their efficiency in reducing potential silicone oil adherence to the IOL optics. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Five groups of rigid and foldable IOLs were analyzed in an in vitro test for the percentage of silicone oil adherence: a single-piece foldable hydrophilic-acrylic IOL (n = 9); a single-piece rigid poly(methyl methacrylate) (PMMA) IOL with HSM coating of the lens optic (n = 9); a 3-piece foldable silicone optic IOL with HSM coating of the optic (n = 10); a single-piece standard rigid PMMA IOL (n = 7); and a standard 3-piece foldable silicone optic IOL (n = 9). After the IOLs were immersed in water and then in silicone oil, gross photographs taken. Image analysis was performed to evaluate the percentage of silicone oil coverage of the anterior and posterior surfaces of each IOL optic. RESULTS: The mean silicone oil coverage of the hydrophilic-acrylic IOLs was 5.6% +/- 2.5% (SD); of the HSM PMMA IOLs, 6.2% +/- 4.3%; of the HSM silicone optic IOLs, 6.7% +/- 3.2%; and of the standard PMMA IOLs, 20.3% +/- 13.3%. The mean silicone oil coverage was greatest on the standard silicone optic IOLs, 98.2% +/- 3.1%. CONCLUSIONS: Intraocular lenses with a hydrophilic optic have less tendency toward adherence to silicone oil than more hydrophobic designs. A foldable silicone IOL with heparin surface modification can significantly reduce potential silicone oil adherence, comparable to the level achievable with the rigid HSM PMMA designs. Two new foldable IOL styles, the HSM silicone IOL and IOLs in the general class of hydrophilic-acrylic, were highly efficacious in reducing silicone oil adherence. There is now a real choice of foldable lenses for patients with actual or potential vitreoretinal diseases.     

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。     

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.     

Bacterial adhesion to rigid and foldable posterior chamber intraocular lenses: in vitro study

PURPOSE: To determine the in vitro bacterial adherence to intraocular lenses (IOLs) routinely used at 1 center. SETTING: University Hospital of Vienna, Vienna, Austria. METHODS: Four types of rigid IOLs (hydrophobic poly[methyl methacrylate] [PMMA] and hydrophilic heparin-surface-modified PMMA) and 5 types of foldable intraocular lenses (hydrophobic silicone, hydrophobic acrylic, and hydrophilic acrylic) were used in the experiment. Under standardized conditions, the IOLs were contaminated with 2 strains of Staphylococcus epidermidis. A sonication method and impression method were used for quantification. The mean bacterial density per lens type (colony forming units/mm(2)) was compared. RESULTS: With both germs and both quantification methods, more bacteria was found on hydrophobic lenses than on IOLs with hydrophilic surfaces (P =.001). The Alcon AcrySof and Askin UV80F IOLs had the greatest and the Corneal Acrygel and Bausch & Lomb Hydroview IOLs the least affinity to these microorganisms. CONCLUSION: The data suggest that hydrophilic IOLs can help reduce the rate of postoperative endophthalmitis as a result of their surface properties.     

Optical resolution of silicone and polymethylmethacrylate intraocular lenses

The optical resolution and contrast of 18 silicone and 18 polymethylmethacrylate (PMMA) intraocular lenses were determined before implantation in and after removal from rabbit eyes. A specially designed microphotographic system that allows documentation and comparison of the image quality of different lens types was used. Silicone intraocular lenses showed a mean axial resolution of 1.25, PMMA lenses showed 1.60, of an optotype analogous resolution target (1.0 = 20/20) at a 3 mm pupil opening preoperatively. At one to 16 weeks postoperatively, both types of IOLs demonstrated nearly unchanged resolution. Contrast, however, decreased to between 60% and 85% of the preoperative 100% standard. This decrease was due to precipitates deposited on the lens surface, to posterior capsule opacification, and to lens decentration.     

Intraocular lens materials and styles: A review

Biomaterial science has lead to the development of a variety of foldable intraocular lens (IOL) biomaterials. This literature review examines these lenses from both a basic science and a clinical perspective. By most parameters, hydrogel, soft acrylic and silicone IOL are better than polymethylmethacrylate (PMMA) lenses.
Plate haptic silicone IOL have the lowest incidence of cystoid macula oedema and posterior capsule opacification, but these lenses require an intact anterior capsularhexis and posterior capsule. Yttrium aluminium garnet (YAG) laser capsulotomy must be delayed at least 3 months to avoid posterior lens dislocation. Silicone has the lowest threshold for YAG laser damage of all IOL materials and also adheres irreversibly to silicone oil with subsequent optical impairment. Three piece silicone IOL with polypropylene haptics have a higher incidence of decentration, pigment adherence and capsule opacification compared with PMMA haptics. Hydrogel lenses are very biocompatible and resistant to YAG laser damage, but pigment adheres to the surface more readily than PMMA. Soft acrylic IOL unfold slowly, resulting in controlled insertion, but it is possible to crack the lens and some lenses develop glistenings due to water accumulation.
There are significant socioeconomic implications to the large differences in posterior capsule opacification rates between the various biomaterials and the lens styles.     

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.     

Adherence of triamcinolone acetonide to various intraocular lens materials

PURPOSE: To determine the adherence of triamcinolone acetonide to various intraocular lens (IOL) materials. SETTING: Department of Ophthalmology, Dokuz Eylül University, Izmir, Turkey. METHODS: Four IOLs of 4 materials (single-piece poly(methyl methacrylate) [PMMA], 3-piece foldable silicone, 3-piece hydrophobic acrylic, and single-piece hydrophilic acrylic) were first immersed in triamcinolone acetonide (40 mg/mL) for 15 minutes and then bathed in a balanced salt solution for another 15 minutes. Afterward, each lens optic was examined under light microscopy and digital images were obtained with a digital color video camera. The percentage of optic area covered with triamcinolone acetonide was determined by image analysis. RESULTS: Mean triamcinolone coverage was 7.62% +/- 4.06% (SD) for PMMA IOLs (range 1.97% to 11.43%), 9.09% +/- 4.60% for silicone IOLs (range 4.70% to 15.32%), 8.75 +/- 7.20% for hydrophobic acrylic IOLs (range 1.31% to 16.86%), and 23.16 +/- 8.53% for hydrophilic acrylic IOLs (range 15.02% to 35.12%). Adherence of triamcinolone acetonide to hydrophilic acrylic lenses was statistically significant when compared with other IOL materials. CONCLUSION: Intraoperative triamcinolone injection may obscure visualization intraoperatively and postoperatively, especially in eyes with hydrophilic acrylic lenses, because triamcinolone acetonide seems to have a tendency to adhere to hydrophilic acrylic lenses in vitro.     

Effects of cataract extraction with intraocular lens placement on scanning laser polarimetry of the peripapillary nerve fiber layer

PURPOSE: To determine the effects of cataract extraction with intraocular lens placement on scanning laser polarimetry of the peripapillary nerve fiber layer. DESIGN: Cohort study. METHODS: Thirty-four eyes of 33 patients undergoing phacoemulsification cataract surgery with intraocular lens were imaged using the GDx Nerve Fiber Analyzer within 4 weeks before and at least 4 weeks after cataract surgery. Preoperative and postoperative mean images were compared. The effects of cataract severity and type, and intraocular lens material, were also examined. RESULTS: Comparison of preoperative and postoperative mean scanning laser polarimetry measurements revealed that eyes in which acrylic intraocular lenses (n = 11) were placed had a significant increase in scanning laser polarimetry for the total band circumference, and superior, inferior, and nasal quadrants (P < or =.041). Placement of silicone (n = 15) and polymethylmethacrylate (n = 8) intraocular lenses did not result in statistically significant changes in scanning laser polarimetry measurements. However, eight of 34 eyes (23.5%) had changes of 15% or more postoperatively in the total circumference measurement, including eyes with acrylic, silicone, and polymethylmethacrylate intraocular lenses. CONCLUSIONS: Cataract extraction with intraocular lens was associated with a statistically significant change in mean scanning laser polarimetry values in eyes that received an acrylic intraocular lens. In individual patients, clinically important changes (15% or greater) in scanning laser polarimetry measurements were not uncommon irrespective of intraocular lens type. New baseline scanning laser polarimetry measurements may be warranted in eyes that undergo cataract extraction with intraocular lens.     

Anterior capsule opacification: a histopathological study comparing different IOL styles

OBJECTIVE: To compare the degree of anterior capsule opacification (ACO) in human eyes obtained post-mortem containing various rigid and foldable posterior chamber intraocular lens (PC-IOL) designs. DESIGN: Comparative autopsy tissue study with clinicopathologic correlations. MATERIALS: Four hundred sixty human globes containing the following PC-IOL styles were analyzed: (1) one-piece polymethylmethacrylate (PMMA) optic-PMMA haptic (n = 50), (2) one-piece silicone-plate IOL, large hole (n = 40), (3) one-piece silicone-plate IOL, small hole (n = 67), (4) three-piece PMMA optic-PMMA/Prolene haptic (n = 51), (5) three-piece acrylic optic-PMMA haptic (n = 96), (6) three-piece silicone optic-PMMA haptic (n = 24), (7) three-piece silicone optic-polyimide haptic (n = 40), and (8) three-piece silicone optic-prolene haptic (n = 92). TESTING: The globes were sectioned in the equatorial plane for gross examination and then processed through paraffin; sectioned, and stained with hematoxylin-eosin, periodic acid-Schiff, and Masson's trichrome stains; and examined by light microscopy. MAIN OUTCOME MEASURES: Anterior capsule opacification was scored in each eye by grading the histologic sections from 0 to III, according to the amount (thickness) of proliferative tissue and cells measured in sagittal sections on the inner surface of the anterior capsule at the capsulorhexis margin. RESULTS: The difference among the eight groups was significant (P < 0.0001). Mean ACO scores were highest with the large and small hole one-piece silicone-plate lenses (1.77 +/- 0.86 and 1.28 +/- 0.77, respectively). The lowest mean score was observed in the group of three-piece acrylic optic-PMMA haptics lenses (0.51 +/- 0.52). CONCLUSIONS: Our results confirm previous clinical observations that the rate of ACO is relatively high with plate-haptic silicone IOLs. The lowest rate was noted with the three-piece acrylic optic-PMMA haptic IOL. The IOL design and IOL material are significant factors in the development of ACO.