IOL Surface Research Articles

Anterior chamber intraocular lens implantation in patients with a history of chronic uveitis: Five-year follow-up

To compare the incidence of long-term complications after cataract surgery with primary anterior chamber intraocular lens (AC IOL) implantation in uveitic patients and patients without a history of intraocular inflammation (control group). Single-center private practice. Retrospective clinical study. The study comprised patients who between November 2005 and August 2010 had cataract extraction followed by AC IOL implantation because conventional placement was not possible. Outcome measures were the incidence of intraoperative and postoperative complications, preoperative corrected distance visual acuity (CDVA), and CDVA after 1 year. Of the 39 patients identified through electronic medical records, 17 (17 eyes) had a history of chronic uveitis and 22 (23 eyes) had no intraocular inflammatory disease. There were no significant differences in the incidence of intraoperative and postoperative complications between the 2 groups during follow-up (range 12 to 68 months) (P=.702). Although uveitic eyes had a greater risk for epiretinal membrane formation, the incidence of uveitis flareups attributed to the IOL and deposits on IOL surfaces was comparable to that in the control group (P<.001). The CDVA improved significantly in both groups 1 year after surgery (P<.01 and P<.001, respectively). In uveitic eyes with inadequate capsule support, AC IOL implantation restored visual function without a significant increase in long-term postoperative complications compared with eyes that had no history of uveitis.

Experimental study on surface modification of intraocular lens by cyclosporine A-loaded chitosan nanoparticle

Background Posterior capsular opacification (PCO) following cataract extracapsular extraction is a major cause of the reduction of visual acuity.Topical administration of eye drops is a research hotspot for the prevention of PCO.Objective This study was to evaluate the release of cyclosporine A-loaded chitosan nanoparticles (CyA-CS-NP) by ionic gelation in vitro and its feasibility of modification of the surface of polymethylmethacrylate intraocular lens (PMMA IOL) with CyA-CS-NP.Methods The CS-NP and CyA-CS-NP were prepared by ionic gelation of CS with sodium tripolyphosphate.The characteristics of CS-NP,such as the appearance and mean size,and drug entrapment efficient (EE),loading capacity (LC),and the drug release were studied ; the CyA content on the IOL surface was detected by high performance liquid chromatography (HPLC).The IOL surface modified with CyA-CS-NP was observed by scanning electron microscope and X-ray photoelectron spectroscopy technique (XPS),the changes of elements and chemical bond types between simple plasma processed IOL and CyA-CS-NP modified IOL were analyzed.The transmittance at the wavelength of 360-490 nm and refraction of IOL were detected using back focal length method and spectrophotometer,and the effective resolution of IOL was evaluated according to the instruction of ISO/CD 11979-2.Loops anti fatigue test of IOL referred to the criteria of ISO/CD 11979-3.Results The CS-NP and CyA-CS-NP showed monodisperse,uniform appearance similar to spherical shape with a mean size of (158±18) nm and (219±29) nm,respectively.The CyA-CS-NP had high CyA association efficiency and loading capacity (64.2％ and 7.6％).In vitro release study revealed a fast release on the first day followed by a increased drug release during an 11-day following up.The sustained release was approximately 46.6％ at day 1 and 77.7％ at day 12,respectively.The surface of IOLs with cling film was smooth without CS-NP;while the edge of IOLs appeared a layer of CyA-CS-NP after modification.XPS analysis displayed some elements such as phosphonium,CNH2 and O =CN that appeared on the modified surface,indicating that CyA-CS-NP existed on the surface of IOLs edge.The mean quality of CyA on three IOLs surface after modification was 171.88 μg.The diopter,distinguishing ability and transmittance of modified IOL were (16.64±0.23) D,(90.28 ± 0.25) ％ and (73.57 ±0.62) ％,and those of unmodified IOL were (16.62±0.29) D,(90.28±0.21) ％,(73.61±0.60)％,without significant differences between them (t =0.381,0.078,2.291,all at P ＞ 0.05).The antifatigue ability of loops complied with the criteria of ISO/CD 11979-3.Conclusions The optical property and antifatigue ability of loops of the edge-modified IOLs by CyA-CS-NP reach the normal standard and meet the requirement of clinic application.The edge-modified IOLs by CyA-CS-NP can be a delivery system for intraocular drug release. Key words: Chitosan nanoparticle; Cyclosporin A; Intraocular lens; Ionic gelation; Surface modification

Sulfadiazine modified PDMS as a model material with the potential for the mitigation of posterior capsule opacification (PCO)

Cataract surgery, while the most common surgical procedure performed, leads to posterior capsule opacification in approximately 30% of cases. Transforming growth factor beta 2 (TGF-β2) and matrix metalloproteinases (MMPs) have been shown to play important roles in the cellular processes leading to posterior capsule opacification. Delivery of inhibitors to MMPs may have the potential to inhibit the initial cascade of events that lead to PCO. However, delivery of these molecules via tethering has proven difficult. In this work, sulfadiazine was tethered to polydimethylsiloxane (PDMS) via a polyethylene glycol (PEG) spacer as a potential MMPI mimic. Surface characterization using a variety of methods demonstrated successful modification with the antibiotic. The surfaces were examined with lens epithelial cells to determine their effect on these cellular processes, including cell transdifferentiation and production of extracellular matrix components. The presence of TGF-β2 in the cell culture media was found to stimulate the production of ECM components such as collagen, fibronectin, and laminin, as well as alpha smooth muscle actin (α-SMA), and the migration marker Rho by HLE-B3 and FHL124 cells. In all cases, these effects were decreased but not completely eradicated by the presence of sulfadiazine on the PDMS surfaces. While the level of inhibition necessary for inhibition of PCO in vivo is unknown, these results suggest that IOL surface modification with sulfadiazine has the potential to reduce cellular changes associated with PCO. Furthermore, the results demonstrate for the first time that changes consistent with inhibition of fibrosis may be elicited by surfaces modified with sulfadiazine.

Single IOL surface measurements with UV‐Shack‐Hartmann‐Sensors

AbstractPurpose Measuring single IOL surface topographies remains a difficult task due to reflexes from the second surface. Currently no commercially system is available for this task. The purpose of this study is to discuss the feasibility of a new and customized UV‐SHS (Shack‐Hartmann‐Sensor) method in the field of measuring individual IOL surfaces.Methods The WaveMaster system (Trioptics, Wedel) represents the SHS technique. It is customized to work in the UV range of light spectrum and eliminates the possibility of back surface reflections. Repeatability and reproducibility measurements are performed before measuring spherical and freeform IOLs of different radii of curvature (ROC) between 6 mm and 20 mm. For validation of the measurement system 2 criteria are applied: The correct measurement of a sample’s ROC and the RMS of the residual (the topography after subtracting the best‐fitted‐sphere).Results The repeatability and reproducibility measurements provide acceptable figures; a measurement of a sample’s ROC takes about 5 seconds and delivers accurate results. The maximum deviation from the theoretical design ROC is about 100 µm while many results show a deviation of some µm. The results for spherical IOLs prove that the device can be applied over the whole range of ROCs. The residuals show an RMS deviation of some µm for spherical surfaces and correspondingly higher values for freeform surfaces.Conclusion The UV‐WaveMaster system is an appropriate device for measuring individual IOL surfaces for a wide range of ROCs making it applicable for quality control for freeform IOL surfaces. The acquisition of the sample’s topography and ROC with its residual is fast and. Future application of the device will show its advantages and limitations in detail.

Evaluation of free-form IOL topographies by clinically available topographers

PurposeNo commercially available device for measuring individual IOL surface topographies exists on the market. The purpose of this paper is to show the applicability of clinically available corneal topographers for measuring individual IOLs consisting of a spherical surface on one side and a freeform surface on the other side. MethodsThree measurement principles (Placido rings: Tomey TMS-2N, Scheimpflug: Oculus Pentacam, optical coherence tomography: Tomey CASIA) are applied in determining the IOLs’ surface and compared against the design data used for producing the surfaces. Spherical and freeform IOLs are measured and analysed in both radius of curvature (ROC) and higher-order residual parameters by analysing the residuals. ResultsRepeatability and reproducibility measurements show a sub-μm precision for the TMS-2N system, while the Pentacam's values are located around 10μm and the CASIA system's values gather around 20μm. The TMS-2N system works best at detecting a sample's ROC and residual properties within the range of 8mm to 13.5mm mean ROC. In this range, the deviations from the theoretical ROC are about 45μm. The Pentacam doesn’t have this limitation, but faces problems with exporting measurements of freeform surfaces. In some circumstances the program crashes and prevents the export. If being able to export the Pentacam measurements show an average deviation of 100μm from the theoretical ROC value. The CASIA system shows high amounts of noise which makes it not applicable in this field, having deviations of several 100μm from the theoretical ROC value. Residual comparison for the higher-order samples shows sub-μm precision for the TMS-2N, about 1μm precision for the Pentacam and several μm for the CASIA system. The values for the customized samples are slightly increased, several μm for the TMS-2N, up to 30μm for the Pentacam system and around 75μm for the CASIA system. ConclusionThe TMS-2N system is an appropriate device for measuring individual IOL surface topographies for ROCs between 8mm to 13.5mm. The Pentacam and CASIA induced relatively high level of variation and noise. Future application of the TMS-2N in this field will reveal its long-term statistics.

Surface Modification of Hydrophobic PMMA Intraocular Lens by the Immobilization of Hydroxyethyl Methacrylate for Improving Application in Ophthalmology

To improve application of hydrophobic polymethyl methacrylate intraocular lens (PMMA IOL) in a convenient and continuous way, 2-hydroxyethyl methacrylate (HEMA) was immobilized by dielectric barrier discharge plasma at relatively high pressure. The hydrophilicity and topography of the modified IOL surface were comprehensively evaluated by contact angle and atomic force microscopy, while the surface biocompatibility of the modified IOL was investigated by platelets adhesion and cells proliferation experiments. The results revealed that the hydrophilicity of the HEMA-g-PMMA IOL samples were significantly and permanently improved. Less platelets attachment was observed on the modified IOL, especially in the HEMA2-g-PMMA IOL group (with 1.65 × 10−1 mol/L HEMA concentration), which also suppressed the proliferation of cells.

Cell adhesion on explanted intraocular lenses: Part 2: Experimental study of a surface-modified IOL in rabbits

To develop a hydrophobic acrylic IOL with a hydrophilic, anti-cell adhesive surface characteristic. Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. Experimental study. Hydrophobic acrylic IOLs were coated with hydrophilic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer and implanted in rabbit eyes following lens extraction. Cell adhesion on the IOL surface was histologically compared with that on an uncoated IOL under light microscopy. Specimens were also observed under scanning electron microscopy to examine the effects of MPC coating on cell morphology. Hydrophilic MPC coating reduced cell adhesion on acrylic IOLs at 1 month postoperatively. Coating an acrylic IOL with a hydrophilic polymer inhibited cell adhesion on the IOL surface.

Präzision eines neuen Biometriegeräts zur Messung pseudophaker Augen

Biometric measurements and the knowledge of interrelationships of structures within the eye are especially mandatory for cataract and refractive surgery. As the number of pseudophakic patients steadily increases because cataract surgery becomes more easily available all over the world, exact biometry of eyes with crystalline lenses as well as pseudophakic eyes is gaining interest. In the present study we compared biometric measurements in pseudophakic eyes using a new optical low-coherence reflectometry (OLCR) device with results measured by the IOLMaster. In this prospective study 140 pseudophakic eyes from 123 adult volunteers following uneventful cataract surgery and IOL implantation were examined at the International Vision Correction Research Centre (IVCRC) at the University of Heidelberg, Germany. The aim of this study was to evaluate a functional prototype of the new LENSTAR LS 900 (Haag-Streit)/ALLEGRO BioGraph (Wavelight) biometer and the IOLMaster V.5 (Carl Zeiss Meditec) and to compare axial length (AL) and keratometry measurements with those obtained by the IOLMaster. Additionally we investigated whether the LENSTAR/BioGraph can detect anterior chamber depth (ACD) and the effective lens position (ELP) of IOLs by OLCR in pseudophakic eyes. Patients with corneal or intraocular pathology and patients who had undergone other surgery in the investigated eye or whose cataract surgery dated back less than 4 weeks were not included in the study. Measurements were repeated with both devices as recommended by the manufacturers. Results were compared using Bland-Altman plots, Passing Bablok regression analysis and Pearson correlation calculations (MedCalc version 7.3.0.1). Valid axial length measurements were available in 137 eyes. The mean values were 23.75mm for both devices (SD±2.08 with the IOLMaster, ±1.7 with the LENSTAR/BioGraph). The mean corneal radius (R) was 7.7±0.27mm (IOLMaster) vs. 7.74±0.29mm (LENSTAR/BioGraph). Valid ACD measurements with the LENSTAR/BioGraph were achieved in 30% of all cases. In 98.6% of the eyes in which ACD was analyzed manually a mean ACD of 4.73±0.53mm was found. Both devices tested in this study showed a high correlation for AL and keratometry measurements. ACD measurements performed with the LENSTAR/BioGraph showed a measurable signal but the prototype calculated a value only in the minority (30%) of cases. This study showed that on the one hand the LENSTAR/BioGraph has the potential to be a reliable and useful machine for clinical everyday routine: This space and time-saving device includes several features which make it a patient and user friendly tool for diagnostics as well as screening. On the other hand we found that the software used in the prototype could be improved especially in order to identify IOLs and to measure reliable ACD values in pseudophakic patients. IOL surfaces did not generate sufficient interference signals in the LENSTAR/BioGraph and although the light reflected by the IOL surfaces was recognized by the device the software version used in this study did not generate numerical results for ACD.

Enhancement of Refractive Results after Intraocular Lens Implantation

Summary:An overview on polypseudophakia (‘piggyback’ intraocular lens [IOLs]) is given. Requirements on a sulcus-supported supplementary IOL are defined. Two-year results of a new IOL (Sulcoflex®) are presented and indications for this IOL are defined.Methods:The IOL is especially designed for implantation into the ciliary sulcus in pseudophakic eyes (piggyback). It is a single-piece implant made of hydrophilic acrylic. Optic- and haptic-edges are round. The optic has a diameter of 6.5mm and a concave/convex shape for perfect fit on the anterior convex surface of the primary IOL. The haptic is angulated, and has an undulated design to preclude IOL rotation. A monofocal, a multifocal or a toric version of the sulcoflex IOL were implanted into the ciliary sulcus of pseudophakic eyes. All IOLs were implanted by injector through a 3mm clear cornea incision. After surgery near and far uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) and eye pressure were assessed. Inflammation was measured by laser flare/cell meter. Position and rotational stability of the IOL were documented regularly at all control visits. Furthermore, Scheimpflug photography and ultrasound biomicroscopy were performed.Results:Surgery was performed without any complication in all cases. Two years after surgery there were no severe intra- or post-operative complications detected. Emmetropia was achieved in all cases (±0.25dpt) and the refraction was stable. Flare values were lower than the values measured after standard cataract procedures. Rotational stability and centration were excellent. Intraocular pressure was within the normal range at all visits. After one year of follow-up no iris-chafing was documented. In all cases, a good distance was found between iris and the Sulcoflex-IOL and primary implant and the Sulcoflex-IOL. In those cases with the multifocal IOL-version all patient achieved independency from glasses.Conclusion:Surgery with implantation of a sulcus-IOL is safe and less traumatic than IOL-exchange. The material and design of the Sulcoflex IOL ensure that the implants are well tolerated within the eye. The implant can be used at the same time with the primary implant or as secondary implant. Indications for implantation of this IOL are the correction of ‘post-surgical’ ametropia, of astigmatism (toric IOL) of higher order aberrations (aspherical IOL) and of ‘pseudophakic presbyopia’ (multifocal IOL). In the future, other potential indications will be established.

Computerized calculation scheme for retinal image size after implantation of toric intraocular lenses

To describe a paraxial computing scheme for tracing an axial pencil of rays through the 'optical system eye' containing astigmatic surfaces with their axes at random. Two rays (-10 prism diopters from vertical and horizontal) are traced through the uncorrected and corrected eye. In the uncorrected eye one specific ray is selected from the pencil of rays, which passes through the pupil center. In the corrected eye any ray can be traced through the eye. From the slope angle, the intersection of the ray with the refractive surface and the refraction the slope angle of the exiting ray is determined and the ray is traced to the subsequent surface. From both rays traced through the eye an ellipse is fitted to the image to characterize the image distortion of an circular object. Assumptions: target refraction -0.5-1.0D/A = 90 degrees at 14 mm, corneal refraction 42.5 + 3.5D/A = 15 degrees, axial length 23.6 mm, IOL position 4.6 mm, central lens thickness 0.8 mm, refractive index 1.42, front/back surface of the toric IOL 10.0 D/7.14 + 6.47D/A = 101.8 degrees. The vertical incident ray was imaged to (x, y) = (0.0055 mm, -1.6470 mm)/(0.0067 mm, -1.6531 mm) in the uncorrected/corrected eye. The horizontal incident ray was imaged to (x, y) = (1.6266 mm, -0.0055 mm)/(1.6001 mm, -0.0067 mm) in the uncorrected/corrected eye. The ellipse (semi-major/semi-minor meridian) fitted to the conjugate image of a circle sized 1.648 mm/1.625 mm in an orientation 14.2 degrees in the uncorrected and 1.654 mm/1.599 mm in an orientation 7.1 degrees in the corrected eye. This concept may be relevant for the assessment of aniseikonia after implantation of toric intraocular lenses for correction of high corneal astigmatism.

Factors that influence the development of posterior capsule opacification with a polyacrylic intraocular lens

To identify factors that contribute to posterior capsule opacification (PCO) after implantation of a 5.5 mm polyacrylic (IOL). A retrospective analysis of a cohort of sequential images taken from the PCO database at St. Thomas' Hospital, London, to include all patients with an AcrySof MA30 lens and a 1-year retroillumination image. Records of age, gender, axial length, and PCO measurements using the POCO software system were available. Images were divided into those with greater or less than 10% PCO. The degree of rhexis-IOL contact was recorded in clock hours. Images of 60 eyes were analyzed. Twenty-one eyes had more than 10% PCO. No correlation was found between PCO and age, gender, or axial length. Forty-eight eyes (80%) had some loss of rhexis-IOL contact. These eyes had increased PCO (P < .001) compared with eyes with complete IOL-rhexis contact. More PCO developed when the rhexis was partly on and partly off the IOL. PCO is reduced when the rhexis is in complete contact with the anterior IOL surface. The failure to achieve this accounts for the majority of increased PCO seen in patients implanted with this IOL model. PCO formation is related to surgical technique as well as IOL design, and comparisons cannot be made between IOLs without taking this into consideration. These results support the trend to the use of larger optic IOLs to prevent PCO and also support the "capsule compression" theory of PCO prevention.

Quantitative measurement of the PCCC area in the postoperative period

BACKGROUND/AIMSThe major complication of extracapsular cataract extraction (ECCE) is posterior capsule opacification (PCO). Posterior continuous circular capsulorhexis (PCCC) seems to be very promising in preventing PCO. This study was aimed...

Interaction between inflammatory cells and heparin-surface-modified intraocular lens

Purpose To investigate the interaction and adherence of inflammatory cells to a heparin-surface-modified intraocular lens (HSM IOL). Setting Department of Ophthalmology, Tokyo Medical University Hospital, Tokyo, Japan. Methods Splenic mononuclear leukocytes from rats with experimental autoimmune uveitis were cultured with the optic of an HSM IOL for 96 hours. The number of adherent cells on the HSM IOL surface was measured with and without the addition of interphotoreceptor retinoid-binding protein and concanavalin A (ConA) to the culture medium. The adherent cells were observed under a light microscope or a scanning electron microscope. Results Interphotoreceptor retinoid-binding protein and ConA increased the number of adherent cells on the HSM IOL relative to the control. Adherent cells on the HSM IOL were small and round, considered to be mainly lymphocytes. Conclusion Activated lymphocytes tended to adhere to the surface of the HSM IOL.

Phacoemulsification in eyes with a small pupil

Purpose To evaluate the intraoperative difficulties and long-term outcome of phacoemulsification through a small pupil using minimal iris manipulation. Settings Iladevi Cataract & IOL Research Centre, Ahmedabad, India. Methods This prospective study included 30 consecutive eyes with a maximally dilated pupil size of 4.0 mm or smaller. Except synechiolysis and occasional pupil retraction with a chopper, no iris manipulation was performed. The phacoemulsification technique included creation of deep central space, use of a low aspiration flow rate with appropriate vacuum, and step-by-step chop in situ and lateral separation of the nucleus. Patients were examined 1 day, 1 week, 1 and 3 months, and 1 year postoperatively. Specular microscopy was performed at 1 month and 1 year. Results Fourteen eyes had chronic iritis, 12 had glaucoma surgery, 2 had pseudoexfoliation, and 2 had a rigid pupil. Mean follow-up was 13.6 months. Eighteen eyes (60%) had hard cataract. Mean preoperative pupil size was 2.80 mm ± 0.75 (SD). Mean pupil size before the capsulorhexis was initiated was 4.42 ± 0.58 mm. The iris was bruised in 10 eyes during cortex removal. Trace amounts of cortex were left in 4 cases. Two eyes had increased intraocular pressure in the early postoperative period. Six patients had a minimal amount of retained viscoelastic material (pseudofibrin), and 2 patients developed a sterile hypopyon. Sixteen eyes had cell deposits on the IOL surface and 12 eyes, fine uveal pigments. In 2 eyes with previous glaucoma surgery and in all eyes with iritis except 2, posterior synechias reformed. Conclusion Successful phacoemulsification was done with minimal or no pupil-widening maneuvers, restoring the preoperative pupil configuration.

Intraocular lens explantation in uveitis.

Visual rehabilitation after cataract surgery has been improved with the development of IOLs. These lenses are well tolerated in many uveitis patients when complete control of preoperative inflammation is achieved. However, in some patients, IOL placement after cataract extraction results in chronic inflammation, deposition of inflammatory cells and debris on the IOL surface, and inflammatory membrane formation despite antiinflammatory coverage. Patients with systemic diseases characterized by chronic inflammation, such as sarcoidosis and JRA, and those with chronic ocular inflammatory conditions or inflammation involving the intermediate segment of the eye may be at high risk for these complications. In patients in whom antiinflammatory therapy fails, adequate control of inflammation may be achieved after lens explantation.

Immunohistochemical evaluation of cellular deposits on posterior chamber intraocular lenses.

We used immunohistochemistry to characterize cellular and proteinaceous deposits on the surfaces of explanted posterior chamber intraocular lenses (PC-IOLs). A total of 30 PC-IOLs were immunostained for the alpha- or beta-subunits of prolyl 4-hydroxylase, which is involved in collagen biosynthesis; cellular fibronectin; alpha B crystalline; and CD68, a macrophage marker, to characterize the cellular deposits that adhere to the IOL surfaces and to evaluate the distribution of cells involved in the deposition of extracellular matrix on IOLs. Cellular or proteinaceous deposits were observed on all 30 PC-IOLs. Cells that showed positive staining for alpha B crystallin were classified as lens epithelial cells; CD68-positive cells were considered to be of macrophagic origin. Positivity for cellular fibronectin, including the macrophages and related cells, appeared to be responsible for the accumulation of fibronectin on the surfaces of PC-IOLs. Prolyl 4-hydroxylase-positive cells were involved in the deposition of collagen on PC-IOLs. Immunohistochemical study revealed that macrophages, foreign-body giant cells, and lens epithelial cells adhered to explanted PC-IOLs. Such adherent cells are responsible for the deposition of extracellular matrix on the surfaces of PC-IOLs and may regulate the assembly of the extracellular matrix, influencing the biocompatibility of PC-IOLs.

Use of a fluorescence method for probing protein adsorption to the surface of intraocular lenses

1. The method of FTIR was used for monitoring protein adsorption to IOL. 2. Energy characteristics of adsorption of the other main proteins of the intraocular fluid (α-, β-, and γ-immunoglobulins) to the IOL surface should also be studied to elucidate the mechanisms of biocompatibility of IOL at the stage of protein adsorption.

Correlations between aqueous flare and cells and lens surface cytology in eyes with poly(methyl methacrylate) and heparin-surface-modified intraocular lenses

A prospective, single-surgeon study was performed on 59 patients randomized to receive a poly(methyl methacrylate) intraocular lens or a heparinsurface-modified lens after standardized endocapsular cataract surgery with a routine postoperative regimen. The anterior chamber laser flare and cell measurements and the cellular reaction on the anterior lens surface were monitored for a year following surgery. This report examines the correlations between the anterior chamber flare and cell reaction and the anterior IOL surface cellular reaction. The findings suggest that the early postoperative blood-aqueous barrier breakdown is primarily caused by surgical trauma; by one month the blood-aqueous barrier function is determined by inflammatory mediators released by small monocyte-derived cells on the IOL surface. Giant cells on the IOL surface did not correlate with aqueous flare, which suggests an insignificant capacity to release inflammatory mediators.

In vitro organotypic culture method to evaluate the biocompatibility of heparin-surface-modified intraocular lenses

Using an organotypic culture method, we evaluated the biocompatibility of two kinds of intraocular lenses: conventional poly(methyl methacrylate) (PMMA) and heparin-surface-modified (HSM) PMMA. Chicken corneal endothelium from embryos incubated for 14 days was placed on an agar medium and covered with one of three types of materials: PMMA, HSM PMMA, and a control, Thermanoxa. Experiments at five different times measured cell migration, cell multiplication, and cell adhesion. Scanning electron microscopy showed a low level of corneal endothelial adhesion on the HSM IOL surface. There was a significant difference between the HSM and untreated lenses in migration surface and cell density, with the HSM lenses having better biocompatibility.

Long-term results of implantation of a plate haptic silicone lens in the capsular sac

An important step in developing cataract surgery was the introduction of soft foldable silicone intraocular lenses in the middle 80's. Functional and morphological long-term data are a vital base for definite conclusions on the new material's safety and biocompatibility. Our study presents the long-term results after the implantation of a silicone posterior chamber lens with solid plate haptic design (STAAR AA-4203). All lenses were folded and implanted through a 4-mm small corneoscleral incision. Our study includes 54 eyes in 52 patients with a mean follow-up period of 56.5 +/- 8.9 months. A visual acuity of 20/40 or better was found in 90.7% of all eyes. All except one of the 33 eyes without any further preexisting ocular pathology at the time of the operation achieved a visual acuity of 20/40 or better. Two thirds of all eyes had a horizontal astigmatism of +1.0 D or less. By slitlamp examination more or less dispersed pigment was seen on the IOL's surface in 46.3%. 83% of the silicone lenses were centrated within 0.5 mm. A YAG-laser capsulotomy was performed in 7 cases (13%). IOL-related intraocular inflammations, cystoid macular edema or an elevated intraocular pressure did not occur in this group. Our satisfactory long-term results suggest an excellent biocompatibility of the IOL's design and material.