Interaction of intraocular lenses with various concentrations of silicone oil: an experimental study

The aim of this study was to evaluate the interaction between various widely used intraocular lenses (IOLs) and silicone oils of different viscosities. Four groups of IOLs, including monoblock foldable hydrophilic acrylic IOLs (Morcher, type 92s); monoblock hydrophobic acrylic IOLs (Acrysof-SA60AT, Alcon); single-piece rigid polymethylmethacrylate (PMMA) IOLs (Intraocular Optical International-IOI-65130) and a three-piece foldable silicone optic IOL (CeeOn Edge 911A, Pharmacia UpJohn) were analyzed in vitro to determine the percentage adherence 1,000-centistoke, 1,300-centistoke or 5,000-centistokes silicone oil on the IOL optic. For each IOL type, there was no statistically significant difference in the mean silicone oil coverage (MSC) of the IOL optics for the different viscosities of silicone oil. Silicone IOLs had the highest MSC percentage (79.9%) whereas hydrophilic acrylic IOLs were the least silicone-covered IOLs (7.8%) compared to the other IOL types tested in this study. It is not the concentration of silicone oil that affects silicone oil coverage. When performing small-incision cataract surgery in patients who may require silicone oil injection, foldable hydrophilic acrylic or hydrophobic acrylic lenses should be preferred over standard foldable silicone lenses.     

Physicochemical surface properties of various intraocular lenses.

PURPOSE: It is of major interest to understand how intraocular lens (IOL) surfaces interact with aqueous humor or tissues after implantation. Important parameters to describe the physicochemical surface properties are the contact angle and critical surface tension. Therefore, we performed measurements of the contact angle and critical surface tension of several commercially available IOLs. SETTING: Department of Ophthalmology, Johannes Gutenberg University, Mainz, University Eye Hospital, Tübingen, and Max Planck Institute for Polymer Research, Mainz, Germany. METHODS: A total of 17 commercially available standard quality IOL types (6 of each) of different materials from several manufacturers were studied. Scanning electron microscopy and contact angle measurements using the sessile drop method were made. RESULTS: The sessile drop method differentiated all materials based on their surface forces. The contact angle (mean +/- SD) ranged from 56.5 +/- 3.8b 3. CONCLUSION: Contact angles differed between the IOLs depending on the IOL material with the lowest contact angle in the heparin-surface-modified IOL. The contact angle measurement method generates useful information about the material surface and its potential biomaterial interactions.     

Solvent for removing silicone oil from intraocular lenses: experimental study comparing various biomaterials

PURPOSE: To evaluate the effectiveness of a perfluorocarbon-perfluorohexyloctane (PFHO)-in removing silicone oil from different intraocular lenses (IOLs) and determine whether any removal technique enhances the removal of silicone oil. METHODS: Six IOL materials were analyzed: standard poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, AcrySof, 2 polyHEMAs with different water contents, and a second-generation SLM-2 silicone. One or 2 microL of a highly viscous silicone oil (5700 cs) was applied to the center of each IOL optic. Perfluorohexyloctane (2 mL) was then used to remove the silicone oil by 1 of 3 techniques: immersion of the IOL in PFHO; irrigation of the silicone oil with a small, blunt cannula; mechanical wiping with a PFHO-saturated Merocel swab (used only when irrigation failed). Next, each IOL was examined by light and scanning electron microscopy. The expanse of silicone oil residue remaining on the IOLs was objectively quantified using an integrated computerized analysis system combined with energy-dispersive spectrometry. RESULTS: After application of 1 microL silicone oil, immersion in PFHO did not remove silicone oil from any IOL material. Irrigation with PFHO removed the silicone oil from the HSM PMMA and polyHEMA IOLs, but oil remained on the other lens materials. Mechanical wiping was necessary to remove the oil from the PMMA, AcrySof, and silicone IOLs. Attempts to remove 2 microL of silicone oil produced similar results. Although mechanical wiping of the AcrySof IOL removed all silicone oil, a slight residue remained on the PMMA and silicone IOLs. The PFHO irrigation removed significantly more silicone oil from the HSM PMMA than the unmodified PMMA IOL (P =.001). More silicone oil was removed from polyHEMA IOLs than from the AcrySof or silicone IOLs (P =.05). CONCLUSION: Although PFHO can remove silicone oil, it is of limited usefulness. The effectiveness of PFHO depends on the removal technique, IOL material, and amount of silicone oil present. Based on these results, we recommend PFHO irrigation followed by mechanical wiping with a PFHO-saturated swab.     

Physical characteristics of various intraocular lenses

Physical characteristics of 15 posterior chamber lenses from 15 companies were examined for residual ethylene oxide gas; the content varied from 13 ppm to 78 ppm. Seven lenses met the FDA regulation of less than 25 ppm. Scanning electron microscopic study revealed that molded-type lenses had the smoothest optic surface and cast-molded lenses had a less smooth surface than the plano side. The lathe-cut lens with barrel polishing also had a smooth optic surface. Neodymium: YAG laser shots were delivered to the optic and the spots were examined by phase contrast microscopy. The lenses made of high molecular weight polymethylmethacrylate were more resistant to YAG laser damage. It was concluded that lathe-cut posterior chamber lenses with barrel polishing made of high molecular weight polymethylmethacrylate would be preferable but further studies of polishing compounds are necessary.     

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。     

Retrospective study of binkhorst intraocular lenses

A retrospective study of all Binkhorst implanted lens patients, currently in my practice, was conducted. Sixty-four (64) two-loop Binkhorst lenses were implanted in 53 patients from 1975 to 1989. Sixty percent of the eyss had 20/40 or better vision. Two hundred and thirty-two (232) four-loop Binkhorst lenses were implanted in 178 patients from 1974 to 1988. Seventy-one percent of eyes had 20/40 or better vision. The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article.     

Staining of intraocular lenses with various dyes: a study of digital image analysis

PURPOSE: To evaluate the interaction of various intraocular lens (IOL) materials with commonly used dyes. MATERIALS AND METHODS: One IOL of each of the five groups (polymethylmethacrylate, silicone, three-piece hydrophobic acrylic, single-piece hydrophobic acrylic and single-piece hydrophilic acrylic) was bathed in trypan blue 0.1%, fluorescein sodium 2% and indocyanine green (ICG) 0.5% for 15 min. Digital photographs of the IOLs were obtained prior to bathing and after the 15-min bath in each dye. The same IOLs were immersed in the same dye for another 15 min and digital images were reobtained to depict the 30-min dye uptake. New IOLs from the group that exhibited visible colour change after the 15-min bath were then bathed in twofold dilution and if there was still visible dye uptake, fourfold dilution was performed, repeating the 15-min bath and digital photography. The images were then processed using Adobe Photoshop 5.1 to get mean luminosity and red-green-blue values. These values were compared between the groups and the undyed control. Also, dye washout was observed in serum-containing vials. RESULTS: None of the polymethylmethacrylate, silicone and hydrophobic acrylic IOLs were stained with the dyes used. The only IOL material that changed colour was hydrophilic acrylic and did so with all dyes. The most marked colour change was with fluorescein sodium 2%, the least was with trypan blue 0.05%. Twofold dilution of trypan blue and fourfold dilutions of fluorescein sodium and ICG still stained the hydrophilic acrylic IOL; however, fourfold dilution of trypan blue did not cause a significant colour change. Trypan blue washed out within 6 h, while the IOL stained with ICG remained stained for longer than 24 h. COMMENT: Hydrophilic acrylic IOLs should be used with caution together with dyes since this material demonstrates marked dye uptake and washout may also take some time.     

Clinical and experimental observation of glistening in acrylic intraocular lenses

PURPOSE: To study whether the glistening on implanted acrylic intracular lenses increases or not. METHOD: 1. Prospective study: We studied the glistening on 49 implanted acrylic intraocular lenses, particularly the time of appearance and increase after glistening appeared. 2. Experiment: We kept an intraocular lens immersed in saline solution at 50 degrees centigrade for two hours and then moved this lens into saline solution at 35 degrees centigrade, and observed this lens during immersion. RESULTS: 1. Prospective study: Glistening was present in 28 eyes (57%), and appeared from 2 to 16 months postoperatively. A few months after appearance it become stable and did not increase further. 2. Experiment: On the 10th day after observation, we could see glistening on the lenses. The points of glistening were 10 microns or less in size, and did not change during 60 days of observation. CONCLUSION: The glistening in acrylic intraocular lenses seemed to become stable a few months after appearance. This our experimental method is useful, because it gives us glistening similar to clinical cases in a short time.     

Experimental study of glistening in silicone intraocular lenses

PURPOSE: To assess the whether glistening(GP) occurs on silicon lenses. METHODS: ALLERGAN, SI-40NB and CANON STAAR, AQ110NV lenses(Alcon MA60BM control). The lenses were immersed in 50 degrees C physiological saline solution for 2 hours, and then immersed in 35 degrees C physiological saline solution. Changes in the lens were observed regularly with a slit lamp microscope until the 90th day. RESULTS: Numerous microvacuoles of 10 microns diameter occurred in the MA60BM and of several microns in the SI40NB. Some clouding was seen in the AQ110 NV. CONCLUSION: The presence of numerous microvacuoles in the SI40NB means there may be GP. The light clouding in the AQ110NV that was resolved with drying is thought to be due to particles in the material which cause discoloration.     

不同水分离方式的晶状体摘出术疗效的实验研究

目的比较传统水分离术和核内水分离术在晶状体搞出术中的疗效。方法100只新鲜猪眼随机分成2组,均用撕囊法,玻璃体腔内注入生理盐水娩出晶状体核,用2种不同的水分离方式,观察晶状体皮质残留情况。结果核内水分离法,晶状体皮质残留最少,玻璃体腔内注水量也最少。结论核内水分离法可能成为新的摘出透明晶状体的方法,有望在高度近视透明晶状体摘出术中应用。     

Personal A-constant in relation to axial length with various intraocular lenses

Purpose:

To study the relationship between the axial length and personal A-constant for the 1-piece Tecnis (Abbott ZCB00), AcrySof MA60AC (Alcon) and the Quatrix aspheric preloaded (CROMA) intraocular lenses (IOL).

Materials and Methods:

Patients matching the inclusion criteria were further subdivided according to the implanted IOL in this prospective comparative study. The obtained refractive outcomes were introduced into the formula installed in the biometry machine (Humphrey model 820 ultrasonic biometer) to obtain the personal A-constant for each eye. Polynomial regression analysis was done to study the individualized A-constant for each type of IOL in relation to preoperative axial length measurement.

Results:

Two hundred and forty five eyes of 186 patients were enrolled into this study, of whom 73 eyes with Tecnis 1-piece, 116 eyes with MA60AC, and 56 eyes with Quatrix. The median of personalized A-constant for Tecnis 1-piece, MA60AC, and Quatrix were 119.21 (SD 1.3, Std. Mean error 0.15), 119 (SD 1.2, Std. Mean error 0.11) and 120.4 (SD 1.2, Std. Mean error 0.16) respectively. Regression plots for the same range of axial length among all the groups showed that the Tecnis1 group followed the same pattern of the Quatrix group in which there was a linear relationship of a trend towards myopia when the axial length had increased and a hyperopic shift when decreased. This relationship changed into a plateau when the axial length became in the range of 23.5 mm to 27 mm in the MA60AC group.

Conclusions:

Personal A-constant follows different trends with different IOLs even for the same range of axial length.     

Intraocular silicone lenses in silicone oil: an experimental study

Background: To evaluate a potential effect of silicone oil on flexible silicone intraocular lenses, four lenses (STAAR AA-4203) were stored in silicone oil under sterile conditions for periods between 1 month and 3 years. Method: The edge and surface of the lenses were examined by scanning electron micrography and the findings compared with a lens of the same model which had been stored in Ringer's solution for 2 years. Results: After 1 year of silicone oil exposure, droplets of different sizes adherent to the surface of the lens were found. These changes proceeded to a wave-like appearance of the surface after 2 and 3 years of storage, so that a continuous layer of silicone oil polymers is probably covering the intraocular lens. Conclusion: Optical interference has to be considered a possibility if it turns out that the droplets cannot be removed during silicone oil evacuation. Consequently silicone intraocular lenses without hydrophilic preparation of the surface should not be implanted in eyes undergoing combined anterior and posterior segment surgery with silicone oil tamponade or in eyes with high risk for vitreoretinal complications.The authors state that they have no proprietary interest in the marketing of the products mentioned herein or competing products     

Clinical and experimental observation of glistening in acrylic intraocular lenses.

PURPOSE: To determine whether or not glistening particles in implanted acrylic intraocular lenses (IOL) increase with the passage of time. METHODS: Prospective clinical study: Glistenings were evaluated in 31 patients (49 eyes) with implanted acrylic IOL, the emphasis being on when glistening first became evident and subsequent changes in the number of glistening particles. Experiment: IOLs were monitored for any changes that occurred with the passage of time as they were immersed first in a 50 degrees C saline solution and then in another saline solution with a temperature of 35 degrees C. RESULTS: Prospective clinical study: Glistening phenomenon was observed in 28 IOLs (57%) 2 to 16 months after implantation (mean = 6.6 months). Glistenings reached their peak in number within a few months of formation in all cases, showing no further increase thereafter. Experiment: Glistening particles first appeared on the 10th day of the experiment in sizes ranging from 3 to 10 microm in diameter. They remained at the same level for the next 60 days without showing any increase. CONCLUSIONS: Glistening formation in acrylic IOLs was found to stabilize within a few months after appearance. The method of our experiment proved reliable in producing, in a relatively short period of time, glistening similar to that found in patients.     

Impact of fibronectin on surface properties of intraocular lenses

Purpose  Physical properties of intraocular lens (IOL) surfaces determine biocompatibility. IOL hydrophobicity of commercially available IOLs with and without fibronectin (FN) coating can be determined by surface contact angle (SCA) measurements. SCA data of IOLs may allow for a rational selection of an IOL type as a function of underlying eye disease. Setting  University Hospital of Saarland, Homburg (Saar), Germany Methods  Thirteen IOL types were tested. IOLs were made of poly(methyl methacrylate)(PMMA), acrylate, or silicone. Select IOLs were surface modified by the manufacturer with heparin or a polysaccharide coating. SCA values of IOLs, either uncoated or precoated with FN, were determined using the sessile water drop method. Results  SCA values ranged from 61.3 to 116.1° for unmodified IOLs, with PMMA IOLs being more hydrophilic (median SCA, 74.1°), silicone IOLs more hydrophobic (median SCA, 113.3°), and acrylate IOLs intermediate (median SCA, 86.6°). Upon FN coating, all genuine acrylate lenses became significantly more hydrophilic while this effect was either nonsignificant or opposite on some PMMA and silicon IOLs. Heparin or polysaccharide surface modification resulted in significantly reduced SCA values. On acrylate IOLs, SCA values did not correlate with the aqueous content of the material. Conclusions  This study associates IOL materials, surface modifications, and the role of FN preadsorption with SCA values reflecting surface hydrophobicity versus hydrophilicity. It provides a rationale for specific IOL selection as a function of the clinical setting, and a basis for IOL development using tailored surface physicochemistry to enhance biocompatibility and to reduce susceptibility to implant infection. Financial disclosure  None of the authors has a commercial or proprietary interest in any of the products discussed in this article.     

Angle-supported intraocular lenses: a goniophotographic study

Twenty-eight eyes were followed prospectively by goniophotography after cataract surgery. Ten had no intraocular lens (IOL), ten had the "Azar 91Z" lens implanted and eight had the Cilco "Optiflex" lens inserted. Iris-haptic synechia or burial occurred in 9 of 10 of the "91Z" group and three of eight of the "Optiflex" lenses. These changes developed predominantly in the inferior angle and were seen as soon as 4 weeks postoperatively. Based on this data, preoperative gonioscopy is recommended prior to removal of these IOLs. Cutting buried haptics and leaving them within iris stroma may be a safe surgical alternative which avoids undue trauma to the anterior segment.     

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