Henny Beckers - Academia.edu (original) (raw)

Papers by Henny Beckers

Macromolecular Bioscience, Jun 13, 2023

Fibrosis of the filtering bleb is one of the main causes of failure after bleb‐forming glaucoma s... more Fibrosis of the filtering bleb is one of the main causes of failure after bleb‐forming glaucoma surgery. Intraoperative application of mitomycin C (MMC) is the current gold standard to reduce the fibrotic response. However, MMC is cytotoxic and one‐time application is often insufficient. A sustained‐release drug delivery system (DDS), loaded with MMC, may be less cytotoxic and equally or more effective. Two degradable (polycaprolactone (PCL) and polylactic‐co‐glycolic acid (PLGA)) MMC‐loaded DDSs are developed. Release kinetics are first assessed in vitro followed by rabbit implants in conjunction with the PRESERFLO MicroShunt. As a control, the MicroShunt is implanted with adjunctive use of a MMC solution. Rabbits are euthanized at postoperative day (POD) 28 and 90. The PLGA and PCL DDSs release (on average) 99% and 75% of MMC, respectively. All groups show functioning blebs until POD 90. Rabbits implanted with a DDS show more inflammation with avascular thin‐walled blebs when compared to the control. However, collagen is more loosely arranged. The PLGA DDS shows less inflammation, less foreign body response (FBR), and more complete degradation at POD 90 when compared to the PCL DDS. Further optimization with regard to dosage is required to reduce side effects to the conjunctiva.

PLOS ONE, Sep 2, 2022

Glaucoma is a group of eye conditions that damage the optic nerve, the health of which is vital f... more Glaucoma is a group of eye conditions that damage the optic nerve, the health of which is vital for vision. The key risk factor for the development and progression of this disease is increased intraocular pressure (IOP). Implantable glaucoma drainage devices have been developed to divert aqueous humor from the glaucomatous eye as a means of reducing IOP. The artificial drainage pathway created by these devices drives the fluid into a filtering bleb. The long-term success of filtration surgery is dictated by the proper functioning of the bleb and overlying Tenon's and conjunctival tissue. To better understand the influence of the health condition of these tissues on IOP, we have developed a mathematical model of fluid production in the eye, its removal from the anterior chamber by a particular glaucoma implant-the PRESERFLO ® MicroShunt-, drainage into the bleb and absorption by the subconjunctival vasculature. The mathematical model was numerically solved by commercial FEM package COMSOL. Our numerical results of IOP for different postoperative conditions are consistent with the available evidence on IOP outcomes after the implantation of this device. To obtain insight into the adjustments in the implant's hydrodynamic resistance that are required for IOP control when hypotony or bleb scarring due to tissue fibrosis take place, we have simulated the flow through a microshunt with an adjustable lumen diameter. Our findings show that increasing the hydrodynamic resistance of the microshunt by reducing the lumen diameter, can effectively help to prevent hypotony. However, decreasing the hydrodynamic resistance of the implant will not sufficiently decrease the IOP to acceptable levels when the bleb is encapsulated due to tissue fibrosis. Therefore, to effectively reduce IOP, the adjustable glaucoma implant should be combined with a means of reducing fibrosis. The results reported herein may provide guidelines to support the design of future glaucoma implants with adjustable hydrodynamic resistances.

Microsystems & Nanoengineering, Jul 20, 2023

The key risk factor for glaucoma is increased intraocular pressure (IOP). Glaucoma drainage devic... more The key risk factor for glaucoma is increased intraocular pressure (IOP). Glaucoma drainage devices implanted in the eye can reduce IOP and thus stop disease progression. However, most devices currently used in clinical practice are passive and do not allow for postsurgical IOP control, which may result in serious complications such as hypotony (i.e., excessively low IOP). To enable noninvasive IOP control, we demonstrate a novel, miniature glaucoma implant that will enable the repeated adjustment of the hydrodynamic resistance after implantation. This is achieved by integrating a magnetic microvalve containing a micropencil-shaped plug that is moved using an external magnet, thereby opening or closing fluidic channels. The microplug is made from biocompatible poly(styrene-block-isobutylene-block-styrene) (SIBS) containing iron microparticles. The complete implant consists of an SIBS drainage tube and a housing element containing the microvalve and fabricated with hot embossing using femtosecond laser-machined glass molds. Using in vitro and ex vivo microfluidic experiments, we demonstrate that when the microvalve is closed, it can provide sufficient hydrodynamic resistance to overcome hypotony. Valve function is repeatable and stable over time. Due to its small size, our implant is a promising, safe, easy-to-implant, minimally invasive glaucoma surgery device.

Scientific Reports, Sep 28, 2021

The aim of this study was to evaluate repeatability, reproducibility, and agreement of three comm... more The aim of this study was to evaluate repeatability, reproducibility, and agreement of three commonly used tonometers in animal research (TonoLab, TonoVet, and TonoPEN AVIA) in a cohort of 24 rabbits. Additionally, the impact of sedation on IOP was investigated in 21 New Zealand White rabbits with the TonoVet tonometer. Repeatability was determined using the coefficient of variation (CoV) for two observers. For the TonoLab (6.55%) and TonoVet (6.38%) the CoV was lower than for the TonoPEN AVIA (10.88%). The reproducibility was highest for the TonoVet (0.2 ± 3.3 mmHg), followed by the TonoLab (0 ± 12.89 mmHg) and lowest for the TonoPEN AVIA (− 1.48 ± 10.3 mmHg). The TonoLab and TonoVet showed the highest agreement (r = 0.85, R 2 = 0.73). After sedation, a significant IOP reduction (often > 25%) was observed. Our results show that among the three tonometers tested, the TonoVet tonometer is best for use in rabbits while the TonoLab should be avoided. The impact of sedation on IOP was substantial and should be taken into account during experimentation.

Medical Problems of Performing Artists, Sep 1, 2016

Eye, Jul 16, 2021

People interested in the research are advised to contact the author for the final version of the ... more People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Medical Education, 1989

Performance tests are logistically complex and time consuming. To reach adequate reliability long... more Performance tests are logistically complex and time consuming. To reach adequate reliability long tests are imperative. Additionally, they are very difficult to adapt to the individual learning paths of students, which is necessary in problem-based learning. This study investigates a written alternative to performance-based tests. A Knowledge Test of Skills (KTS) was developed and administered to 380 subjects of various educational levels, including both first-year students and recently graduated doctors. By comparing KTS scores with scores on performance tests strong convergent validity was demonstrated. The KTS failed discriminant validity when compared with a general medical knowledge test. Also the identification of sub-tests discriminating between behavioural and cognitive aspects was not successful. This was due to the interdependence of the constructs measured. The KTS was able to demonstrate differences in ability level and showed subtle changes in response patterns over items, indicating construct validity. It was concluded that the KTS is a valid instrument for predicting performance scores and could very well be applied as supplementary information to performance testing. The relative ease of construction and efficiency makes the KTS a suitable substitute instrument for research purposes. The study also showed that in higher ability levels the concepts which were meant to be measured were highly related, giving evidence to the general factor theory of competence. However, it appeared that this general factor was originally non-existent in first-year students and that these competencies integrate as the educational process develops.

Nederlands Tijdschrift voor Geneeskunde, 2002

European Ophthalmic Review, 2019

Minimally Invasive Glaucoma Surgery with a New Ab-externo Subconjunctival Bypass-Current Status a... more Minimally Invasive Glaucoma Surgery with a New Ab-externo Subconjunctival Bypass-Current Status and Review of Literature T he PRESERFLO™MicroShunt (Santen, Osaka, Japan) is a new ab-externo, subconjunctival, minimally invasive glaucoma drainage device for surgical treatment of patients with early to advanced primary open angle glaucoma. It is made of a new polymer, 'SIBS' (poly[styrene-block-isobutylene-block-styrene]), and consists of an 8.5-mm long tube with an outer diameter of 350 μm and a lumen diameter of 70 μm. Placement of the device is combined with intraoperative application of mitomycin C (MMC). The MicroShunt received the CE Mark in 2012 but was only released for sale in the European market in 2019. Outside Europe, the device is currently being tested in Canada, Singapore, the USA and the Dominican Republic. Published evidence is still limited; however, study results to date show that a mean intraocular pressure (IOP) reduction of 30-55% from baseline can be achieved, with a substantial reduction in glaucoma medications. Current studies also suggest that an MMC concentration of 0.4 mg/mL is more effective than 0.2 mg/mL. Success rates (i.e., no failures [IOP ≥21 mmHg or <20% IOP reduction] with or without glaucoma medication) were found to vary between 80-100% at 1-2 years of followup. Adverse events (e.g. hyphema, hypotony, shallow anterior chamber or choroidal effusion in 10-25% of cases) were mild. They usually occurred within the first postoperative week and spontaneously resolved within 1-3 months. No long-term sight-threatening complications have been reported so far. Patients are usually satisfied with the procedure. Although more robust data are needed, these first studies suggest that the PRESERFLO MicroShunt is a promising new, minimally invasive procedure for glaucoma.

Bohn Stafleu van Loghum eBooks, Oct 27, 2017

Alle rechten voorbehouden. Niets uit deze uitgave mag worden verveelvoudigd, opgeslagen in een ge... more Alle rechten voorbehouden. Niets uit deze uitgave mag worden verveelvoudigd, opgeslagen in een geautomatiseerd gegevensbestand, of openbaar gemaakt, in enige vorm of op enige wijze, hetzij elektronisch, mechanisch, door fotokopieën of opnamen, hetzij op enige andere manier, zonder voorafgaande schriftelijke toestemming van de uitgever. Voor zover het maken van kopieën uit deze uitgave is toegestaan op grond van artikel 16b Auteurswet j° het Besluit van 20 juni 1974, Stb. 351, zoals gewijzigd bij het Besluit van 23 augustus 1985, Stb. 471 en artikel 17 Auteurswet, dient men de daarvoor wettelijk verschuldigde vergoedingen te voldoen aan de Stichting Reprorecht (Postbus 3060, 2130 KB Hoofddorp). Voor het overnemen van (een) gedeelte(n) uit deze uitgave in bloemlezingen, readers en andere compilatiewerken (artikel 16 Auteurswet) dient men zich tot de uitgever te wenden. Samensteller(s) en uitgever zijn zich volledig bewust van hun taak een betrouwbare uitgave te verzorgen. Niettemin kunnen zij geen aansprakelijkheid aanvaarden voor drukfouten en andere onjuistheden die eventueel in deze uitgave voorkomen.

Translational Vision Science & Technology, Aug 26, 2022

Eye, Mar 21, 2023

BACKGROUND: In most cases, glaucoma patients require long-term medical and/or surgical treatment.... more BACKGROUND: In most cases, glaucoma patients require long-term medical and/or surgical treatment. Preference studies investigate how different aspects of glaucoma management, such as health or process outcomes, are valued and herewith help stakeholders make care more responsive to patients' needs. As, to our knowledge, no overview of these studies is currently available, this study aims to systematically review and critically appraise these studies. METHODS: A systematic literature review was conducted using keywords for stated-preference studies and glaucoma up to October 2021. Studies were included if they were original research and used a stated-preference methodology to investigate preferences in patients or healthcare professionals for different aspects of glaucoma management. Data were extracted and summarized. Furthermore, a quality appraisal of the included studies was performed using two validated checklists. RESULTS: The search yielded 1214 articles after removal of duplicates. Of those, 11 studies fulfilled the inclusion criteria. Studies aimed to elicit preferences for glaucoma treatment (27%), glaucoma related health state valuation (36%), and services (36%) from the patient (91%) or ophthalmologists' perspective (9%). Altogether studies included 69 attributes. The majority of attributes were outcome related (62%), followed by process (32%) and cost attributes (6%). Outcome attributes (e.g., effectiveness) were most often of highest importance to the population. CONCLUSIONS: This systematic review provides an up-to-date and critical review of stated-preference studies in the field of glaucoma, suggesting that patients have preferences and are willing to trade-off between characteristics, and revealed that outcome attributes are the most influential characteristics of glaucoma management.

Eye, Jun 14, 2021

Glaucoma is a progressive optic neuropathy that is the second leading cause of preventable blindn... more Glaucoma is a progressive optic neuropathy that is the second leading cause of preventable blindness worldwide, after cataract formation. A rise in the intraocular pressure (IOP) is considered to be a major risk factor for glaucoma and is associated with an abnormal increase of resistance to aqueous humour outflow from the anterior chamber. Glaucoma drainage devices have been developed to provide an alternative pathway through which aqueous humour can effectively exit the anterior chamber, thereby reducing IOP. These devices include the traditional aqueous shunts with tube-plate design, as well as more recent implants, such as the trabeculectomy-modifying EXPRESS ® implant and the new minimally invasive glaucoma surgery (MIGS) devices. In this review, we will describe each implant in detail, focusing on their efficacy in reducing IOP and safety profile. Additionally, a critical and evidence-based comparison between these implants will be provided. Finally, we will propose potential developments that may help to improve the performance of current devices.

Graefes Archive for Clinical and Experimental Ophthalmology, 1994

The sympathetic innervation of the rat anterior eye segment and related peripheral ganglia was st... more The sympathetic innervation of the rat anterior eye segment and related peripheral ganglia was studied using light and electron microscopic autoradiography after anterograde tracing with 3H-leucine from the superior cervical ganglion. In the trigeminal and pterygopalatine ganglia, unmyelinated nerve fibers were labeled. Some fibers contained accumulations of small vesicles. Close apposition of these labeled sympathetic fibers with other unmyelinated fibers was common, and was also observed at sites where accumulations of vesicles were found. In the iris, ciliary body and trabeculum, numerous fibers and vesicle-containing varicosities were labeled, which all had a similar morphology. No labeling was found in the cornea. Sympathetic fibers traversing the trigeminal and pterygopalatine ganglion closely appose other unmyelinated fibers and contain clusters of vesicles without forming classical synaptic contacts. However, non-synaptic information transfer needs further investigation. The anterior eye segment, except for the cornea, is densely innervated by sympathetic nerve terminals.

PubMed, May 1, 1992

Trigeminal nerve terminals in the rat cornea and iris were ultrastructurally identified using ant... more Trigeminal nerve terminals in the rat cornea and iris were ultrastructurally identified using anterograde tracing with Phaseolus vulgaris-leukoagglutinin (PHA-L). Electron microscopic immunohistochemistry was used to demonstrate the presence and localization of calcitonin gene-related peptide (CGRP) in cornea and iris. In the cornea and iris, nerve fibers were labelled with PHA-L throughout the stroma. Labelling was most obvious within varicosities, densely packed with mainly clear and a few granular vesicles and containing dark mitochondria. Numerous fibers in the stroma of cornea and iris were CGRP-positive. CGRP-positive staining was most intense within varicosities, containing mainly clear and incidentally granular vesicles and dark mitochondria, similar to the structures labelled with PHA-L. CGRP-positive varicosities packed with mainly clear and few granular vesicles also were demonstrated in fibers adjacent to the sphincter and dilator muscles of the iris. In the corneal epithelium, small terminals containing vesicles were CGRP-positive. Trigeminal nerve fibers innervating the rat cornea and iris contained numerous varicosities packed with vesicles. These areas are CGRP-positive, so it can be implied that CGRP is released from these varicosities as a response to triggering impulses. This agrees with the hypothesis that in addition to their afferent function, sensory fibers also exert an efferent modulating function.

Ophthalmic Research, 1993

The distribution of substance P (SP) within the nerve fibers of the rat cornea and iris was studi... more The distribution of substance P (SP) within the nerve fibers of the rat cornea and iris was studied using electron microscopic immunohistochemistry. Numerous SP-immunoreactive fibers were found throughout the corneal and iridal stroma. The most intense staining was found within varicosities containing numerous vesicles. Similar SP-immunoreactive varicosities were found in fibers in close proximity to the iris sphincter and dilator muscles. On account of previous ultrastructural work the SP-containing fibers and varicosities must be assumed to be of trigeminal origin. Additionally, the distribution of SP and calcitonin gene-related peptide (CGRP) in corneal and iridal fibers of rats is similar, suggesting that CGRP and SP are colocalized and may be coreleased from the same varicosities.

Documenta Ophthalmologica, Dec 1, 1994

The peripheral nervous system is classically separated into a somatic division containing both af... more The peripheral nervous system is classically separated into a somatic division containing both afferent and efferent pathways and an autonomic division composed of efferents only. The somatic afferent division is divided in A- and B-neurons. The B-neurons are supposed to be autonomic afferents as part of a reflex system involved in homeostasis. Recent data obtained by neuronal tracing and immunohistochemical

BMC Ophthalmology, Jan 31, 2023

Background Trabeculectomy is the "gold standard" initial surgical procedure for open-angle glauco... more Background Trabeculectomy is the "gold standard" initial surgical procedure for open-angle glaucoma worldwide. During the last decade, the introduction of less invasive procedures, including new bleb-forming surgery such as the MicroShunt, has altered the approach of glaucoma management. At present, there is insufficient evidence comparing the effectiveness between these procedures nor versus trabeculectomy. Furthermore, there is no data available on patient impact and cost-effectiveness. This study aims to address this gap in evidence and establish whether MicroShunt implantation is non-inferior compared to trabeculectomy with regard to effectiveness and whether it is cost-effective. Methods A multicentre, non-inferiority, randomised controlled trial (RCT) studying open-angle glaucoma with an indication for surgery will be conducted. Patients with previous ocular surgery except for phacoemulsification are excluded, as are patients with ocular comorbidity compromising the visual field or requiring a combined procedure. After informed consent is obtained, patients will be randomly allocated to the intervention, a PRESERFLO ™ MicroShunt implantation, or the control group, trabeculectomy, using block randomisation (blocks of 2, 4 or 6 patients). In total, 124 patients will be randomised in a 1:1 ratio, stratified by centre. The primary endpoint will be intraocular pressure (IOP) one year after surgery. Secondary outcomes include IOP-lowering medication use, treatment failure, visual acuity, visual field progression, additional interventions, adverse events, patient-reported outcome measures (PROMs), and cost-effectiveness. Study outcomes will be measured up to 12 months postoperatively. Discussion This study protocol describes the design of a multicentre non-inferiority randomised controlled trial. To this date, cost-effectiveness studies evaluating the MicroShunt have not been undertaken. This multicentre RCT will provide more insight into whether MicroShunt implantation is non-inferior compared to standard trabeculectomy regarding postoperative IOP and whether MicroShunt implantation is cost-effective.