Heparin Surface-modified Lens Research Articles

Exfoliation syndrome and heparin surface modified intraocular lenses

Either heparin surface modified (HSM) or regular polymethyl methacrylate (PMMA) intraocular lenses (IOLs) were implanted after extracapsular cataract extraction in 40 human eyes with exfoliation syndrome in a double-masked, randomized study. The patients were investigated preoperatively, and then 1 day, 1 week, 3, 6 and 12 months postoperatively. In eyes implanted with the HSM IOL, 26% had a fibrinoid reaction anterior to the IOL, while this complication was found in 50% of eyes implanted with the regular IOL. Pigment and cell deposits were more frequent on the regular IOLs than on the HSM lenses postoperatively. Posterior synechia formation between the iris and the implant or lens capsule was more common in the eyes with regular IOL compared to HSM IOL. No difference in visual acuity between the two groups was found either before or after surgery. The results suggest that in eyes with exfoliation syndrome, a heparin surface modified IOL reduces clinical complications associated with cataract surgery.

Effect of heparin-surface-modified intraocular lenses on postoperative inflammation after phacoemulsification: A randomized trial in a United States patient population

Objective To compare postoperative inflammation occurring with heparin-surface-modified (HSM) versus non-HSM polymethyl methacrylate intraocular lenses (IOLs) after phacoemulsification. Design Randomized, double-masked, multicenter, parallel trial. Participants A total of 367 patients, consisting of routine (n = 220), glaucoma (n = 58), and diabetes (n = 89) patients, from eight US medical centers. Methods Patients were observed for 1 year after phacoemulsification and lens implantation (week 1, months 1, 3, 6, 12). Main outcome measures Primary measures of postoperative inflammation defined as the presence of giant cells on the lens surface via specular micrography and cellular deposits via slit-lamp examination. Results The cross-sectional analyses showed that consistently fewer routine patients with HSM lens implants had giant cells on the IOL than those with non-HSM lens implants across all follow-up visits. The statistical significance ( P < 0.05) was observed at all visits except month 12 for routine patients. The diabetes patients also demonstrated the same giant cell difference, and the statistical significance was observed at all visits including month 12. A similar trend was also observed in the glaucoma patients, with statistical significance only at the 3-month visit. For cell deposits, significant differences in favor of the HSM lens ( P < 0.05) were observed at 3 months among routine and diabetes patients, and at 3 and 6 months among glaucoma patients. A longitudinal data analysis using the generalized estimating equation approach indicated statistically significant treatment effect of HSM lenses in reducing inflammation in all patients except for cellular deposits in diabetes patients. In all patient groups, sight-threatening complications were not reported either more frequently or with more severity than normally expected for patients who have undergone cataract extraction and IOL implantation. Conclusions The present study, the only one to have used phacoemulsification in virtually all patients (211/220 [96%] routine, 57/58 [98%] glaucoma, and 84/89 [94%] diabetes) is the largest to evaluate and compare concurrently routine, glaucoma, and diabetes patients. It is also the first US patient population study to document that heparin surface modification reduces postoperative inflammatory responses, as measured by specular micrography and slit-lamp examination, especially in the early postoperative period.

Heparin surface-modified intraocular lenses in patients with inactive uveitis or diabetes

Objective This study aimed to determine whether heparin surface-modified (HSM) intraocular lenses (IOLs) with a hydrophilic surface would reduce cell adherence and other postoperative changes compared with the conventional polymethylmethacrylate (PMMA) IOLs in patients with either diabetes mellitus or inactive uveitis. Design The study design was a randomized, double-masked, clinical trial. Participants Twenty-five patients with bilateral cataracts, 14 with inactive anterior uveitis and 11 with diabetes, with an age range of 11 to 81 years (mean, 52.8 years) participated. Intervention Bilateral cataract extraction with posterior chamber IOL implantation was measured, each patient receiving an HSM lens in one eye and a PMMA lens in the other. Pharmacia one-piece HSM and PMMA IOLs were used. Postoperative ocular changes were evaluated at regular intervals for 24 months in patients with inactive uveitis and for 6 months in patients with diabetes. Patients and physicians alike were unaware of which eye contained which lens until postoperative results were compiled. Records were kept by a study coordinator. Main outcome measures Comparisons of posterior synechiae, IOL cellular deposits, and posterior capsular fibrosis between PMMA and HSM IOLs were measured. Results Using the chi-square test, no statistically significant difference was found between the HSM and PMMA IOLs in the number of cellular deposits found on the anterior IOL surface, the number of adhesions between the iris and IOL, or the incidence of capsular opacification. Conclusion The HSM and PMMA IOLs showed similar postoperative results in patients with inactive uveitis or diabetes mellitus.

Silicone oil adhesion to intraocular lenses: An experimental study comparing various biomaterials

Purpose: To perform an in vitro experimental study comparing the degree of adherence of silicone oil to various rigid and foldable intraocular lens (IOL) designs and to the human lens capsule.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: Seven IOL styles comprising various biomaterials were studied: fluorinetreated (FIuoriens™), heparin-surface-modified (HSM™), hydrogel, Memory-Lens™, poly(methyl methacrylate) (PMMA), soft acrylic, and silicone lenses; the human crystalline lens was also studied. Each lens was immersed in silicone oil for 12 hours, then photographed, studied by scanning electron microscopy (except the crystalline lens), and subjected to computer-generated image analysis to determine the silicone oil coverage.Results: Silicone oil coverage of dry silicone lenses was 100% and of lenses immersed in normal saline, 82.5%. The least coverage was on the heparin-surfacemodified lens (mean score 9.4%). Coverage of the other four lenses ranged from approximately 15.1% to 33.7%. Mean coverage of the human lens capsule was 10.9%.Conclusion: Although a silicone IOL shows maximal adherence to silicone oil, other lens biomaterials are not immune to this complication. Silicone oil coverage was related to the dispersive energy component of the surface charge of the IOL biomaterial. Low dispersive energy materials had less silicone oil coverage, while those with higher dispersive energy had more oil coverage.

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.

Cellular Reactions on Heparin Surface-modified versus Regular PMMA Lenses during the First Postoperative Month: A Double-masked and Randomized Study Using Specular Microphotography

Specular microscopy was used for investigation of cellular reactions on the intraocular lens (10L) anterior surface of Heparin surface-modified (HSM) versus regular polymethyl methacrylate (PMMA) lenses (Pharmacia types 7000 versus 700B, respectively). The double-masked randomized study included 53 patients investigated at 1 and 4 weeks postoperatively. Giant cells were only found on control lenses and more frequently at 4 weeks. Small cells were found on both lens types, but in a higher frequency on the control lenses. The number of small cells decreased during the first 4 weeks on both the control and HSM lenses. However, those control lenses that had giant cells on their surface showed an increase in the number of small cells during the same time. The results of the current study show that HSM lenses give rise to less postoperative inflammatory cellular reactions than regular PMMA lenses.

Intraocular PMMA lenses modified with surface-immobilized heparin: evaluation of biocompatibility in vitro and in vivo

Intraocular lenses (IOL) were surface modified with covalently linked heparin. The surface-bound heparin could not be removed by incubation in solutions known to be effective in breaking non-covalent bonds, nor by incubation in a solution of proteinase K and only to a limited extent by incubation with heparinase. In vitro studies demonstrated improved biocompatibility by the heparin surface-modified lens with respect to outgrowth of fibroblasts and macrophages, activation of granulocytes and adhesion of platelets. These results were subsequently verified in vivo in terms of less inflammatory cells on the lens surface and fewer incidences of synechiae after 3 and 6 wk IOL implantation in the rabbit eye.