Johanna Mm Hooymans

Multiple surface properties of worn RGP lenses and adhesion of Pseudomonas aeruginosa

The aim of this study is to determine rigid gas permeable (RGP) lens surface properties prior to and after wear that are influential on adhesion of Pseudomonas aeruginosa. After 10 and 50 days of wear and after end-stage use, lenses were collected for determination of physico-chemical surface properties and bacterial adhesion in a parallel plate flow chamber. Water contact angles on unused RGP lenses amounted 47+/-13 degrees and were affected by wear. In addition, %O at the lens surfaces, as determined by X-ray photoelectron spectroscopy increased after use for 10 and 50 days, but decreased after end-stage wear. The %N hardly increased after wear and, in line, SDS-PAGE did not indicate adsorbed proteins. The surface roughness of the lenses, as measured by atomic force microscopy amounted 9 nm after 10 and 50 days of use, but end-stage lenses were significantly rougher (48+/-23 nm). Moreover, initial deposition of P. aeruginosa #3 increased with increasing roughness for end-stage lenses. Multiple regression analysis, however, revealed that both physical and chemical surface properties were predictive for initial bacterial deposition to lens surfaces. After 10 days of wear, bacterial deposition was governed by the water contact angle, surface roughness, %O, %N, and %Si, while after 50 days of wear the surface roughness, %N, and %Si were found predictive for bacterial deposition. Initial bacterial deposition to end-stage lenses was solely dependent on the surface roughness. Summarizing, physico-chemical surface properties of RGP lenses change slightly during the first 10-50 days of wear, but end-stage lenses all had increased surface roughness, concurrent with increased bacterial adhesion.

The Incidence of Rhegmatogenous Retinal Detachment in The Netherlands

OBJECTIVE To estimate the incidence and characteristics of rhegmatogenous retinal detachment (RRD) in The Netherlands in 2009. DESIGN Retrospective, observational case series. PARTICIPANTS All patients with RRD in the Dutch population in 2009. METHODS By reviewing surgical logs, cases of primary RRD repair in 2009 were identified. Exclusion criteria included RRD before 2009 and exudative, tractional, or traumatic retinal detachments. Patient demographics, date of surgery, and lens status were documented. Incidence of RRD and 95% confidence intervals (CIs) were calculated based on the Poisson distribution. Age distribution, male-to-female ratio, and proportion of RRD patients with prior cataract extraction (CE) were determined. A Student t test was used to examine differences in the incidence of RRD between groups. MAIN OUTCOME MEASURES Annual RRD incidence in the population and per gender-adjusted age category and proportion of RRD patients with prior CE. RESULTS The annual RRD incidence was 18.2 per 100 000 people (95% CI, 11.4-18.8), with a peak incidence of 52.5 per 100 000 people (95% CI, 29.4-56.8) between 55 and 59 years of age. The Bilateral RRD rate was 1.67%. Macula-off presentation occurred in 54.5% of all RRD patients. Prior CE was noted in 33.5% of RRD eyes. The male-to-female ratio was 1.3:1, and RRD incidence was statistically significantly more frequent in males (P<0.0001). CONCLUSIONS Rhegmatogenous retinal detachment is predominantly a disease of the population older than 50 years, and males are more susceptible to RRD. The annual RRD incidence is highly dependent on demographic characteristics.

Prevention of posterior capsular opacification

Posterior capsular opacification (PCO) is a common complication of cataract surgery. The development of PCO is due to a combination of the processes of proliferation, migration, and transdifferentiation of residual lens epithelial cells (LECs) on the lens capsule. In the past decades, various forms of PCO prevention have been examined, including adjustments of techniques and intraocular lens materials, pharmacological treatments, and prevention by interfering with biological processes in LECs. The only method so far that seems effective is the implantation of an intraocular lens with sharp edged optics to mechanically prevent PCO formation. In this review, current knowledge of the prevention of PCO will be described. We illustrate the biological pathways underlying PCO formation and the various approaches to interfere with the biological processes to prevent PCO. In this type of prevention, the use of nanotechnological advances can play a role.

Pentosidine accumulates in the aging vitreous body: A gender effect

The human vitreous body undergoes structural changes with aging. This can be followed by a posterior vitreous detachment, which can result in ocular pathology. As in many collagenous tissues, age-related changes in the vitreous could be caused by the formation of advanced glycation end products (AGEs). The goal of this study was to find out whether the AGE pentosidine accumulates in the human vitreous with aging. With this data we were able to estimate the half-life of vitreous collagen. Furthermore, we analyzed whether there was a gender difference in pentosidine accumulation, as this was seen in other tissues as well. Using high performance liquid chromatography, pentosidine contents were determined in whole vitreous bodies and in separate parts of vitreous bodies, which were all obtained from human donor eyes. Our results show that pentosidine accumulates in the human vitreous. From the rate of accumulation we could roughly estimate that vitreous collagen has as a similar or shorter half-life compared to skin collagen. This supports the concept of collagen turnover in the vitreous. In general, the female vitreous experiences a faster pentosidine accumulation than the male vitreous, and most of the pentosidine accumulation in the former occurs after 50 years of age.

Presence of Collagen IV in the Ciliary Zonules of the Human Eye An Immunohistochemical Study by LM and TEM

The ciliary zonules of the eye are composed of fibrillar and non-fibrillar components. Fibrils provide tensile strength and elasticity, whereas non-fibrillar components serve as a coating surrounding the fibrils. This coating behaves as a barrier to macromolecules. The present light and transmission electron microscopic (LM and TEM) study identified collagen IV as a novel component of this coating. Collagen IV was demonstrated by pre-embedding and postembedding immunohistochemical (IHC) techniques using monoclonal and polyclonal antibodies. The specificity of the polyclonal anticollagen IV antibody was verified by ELISA. (J Histochem Cytochem 52:789–795, 2004)

Immunohistochemical Evaluation of Idiopathic Epiretinal Membranes and In Vitro Studies on the Effect of TGF-β on Müller Cells

PURPOSE The purpose of this study was to investigate the presence of type VI collagen and glial cells in idiopathic epiretinal membrane (iERM) and the role of TGF-β in the expression of collagens and α-smooth muscle actin (α-SMA) in retinal Müller cells. METHODS Idiopathic ERM samples from vitrectomy were analyzed for glial acidic fibrillary protein (GFAP), cellular retinaldehyde-binding protein (CRALBP), α-SMA, and type VI collagen using flat-mount immunohistochemistry. To study intracellular collagen expression in relation to cellular phenotype, spontaneously immortalized human Müller cells (MIO-M1) were treated with TGF-β1 for 48 hours, and the expression of α-SMA and intracellular type I, II, IV, and VI collagens was studied by using immunocytology. Findings in Müller cells were compared with those in fetal lung fibroblasts and newborn skin fibroblasts. RESULTS A colocalization of GFAP/CRALBP and GFAP/α-SMA was found in iERM, indicating a dynamic process of activation of retinal Müller cells in vivo. Transforming growth factor-β1 induced up-regulation of α-SMA stress fibers in retinal Müller cells and both types of fibroblasts in vitro. The intracellular staining intensity of type I, II, and VI collagens was decreased in retinal Müller cells containing α-SMA stress fibers, whereas the intracellular staining intensity of type I and VI collagens in both types of fibroblasts was not affected. CONCLUSIONS Type VI collagen and activated retinal Müller cells are present in iERM. Transforming growth factor-β1 induces an up-regulation of α-SMA stress fibers in retinal Müller cells and fibroblasts and appears to have a cell-specific effect on intracellular collagen expression.

Force Analysis of Bacterial Transmission from Contact Lens Cases to Corneas, with the Contact Lens as the Intermediary

PURPOSE To determine the probability of transmission of a Staphylococcus aureus strain from a contact lens case, to the contact lens (CL) surfaces, to the cornea, on the basis of bacterial adhesion forces measured by using atomic force microscopy (AFM). METHODS Adhesion forces between S. aureus strain 835 probes with rigid and soft CLs, storage cases, and porcine corneas were measured with AFM and used to calculate Weibull distributions, from which the transmission probability from one surface to another was derived. Bacterial transmission probabilities from force analyses were compared with experimentally obtained transmission data. RESULTS After bond-strengthening, S. aureus adhered to the surface of a lens case with a median force of 10.8 nN. Adhesion forces were different on the soft and rigid CLs (7.7 and 13.6 nN, respectively). Adhesion forces on porcine corneas amounted to 11.8 nN. Data variations were used to calculate the Weibull distribution, from which the probability of transmission from the lens case to a CL and from the CL to the cornea can be directly read. Final transmission probabilities from lens case to the cornea were slightly higher for the rigid (24%) than for the soft (19%) CL. Bacterial transmission determined experimentally increased with increasing contact times, but were within the range of the probabilities derived from Weibull analyses. CONCLUSIONS Probabilities of bacterial transmission from contaminated lens cases to corneas can be derived from Weibull analyses of measured forces of adhesion to the surfaces involved.

Substrate Elastic Modulus Regulates the Morphology, Focal Adhesions, and α-Smooth Muscle Actin Expression of Retinal Müller Cells.

PURPOSE The stiffness of the extracellular matrix has been shown to regulate cell adhesion, migration, and transdifferentiation in fibrotic processes. Retinal Müller cells have been shown to be mechanosensitive; they are involved in fibrotic vitreoretinal diseases. Since fibrosis increases the rigidity of the extracellular matrix, our aim was to develop an in vitro model for studying Müller cell morphology and differentiation state in relation to matrix stiffness. METHODS A spontaneously immortalized human Müller cell line (MIO-M1) was cultured on type I collagen-coated polyacrylamide gels with Youngs moduli ranging from 2 to 92 kPa. Cell surface area, focal adhesion, and the expression and morphology of α-smooth muscle actin induced by transforming growth factor β (TGF-β [10 ng/mL for 48 hours]) were analyzed by immunocytology. The images were documented by using fluorescence microscopy and confocal scanning laser microscopy. RESULTS MIO-M1 cells cultured on stiff substrates exhibited a significant increase in cell surface area, stress fiber, and mature focal adhesion formation. Furthermore, Müller cells treated with TGF-β1 and TGF-β2 and cultured on stiff substrates showed an increased incorporation of α-smooth muscle actin into stress fibers when compared to those grown on soft surfaces. CONCLUSIONS Compliance of the surrounding matrix seems to influence the morphology and contraction of retinal Müller cells in fibrotic conditions. Development of an in vitro model simulating both the normally compliant retinal tissue and the rigid retinal fibrotic tissue helps fill the gap between the results of petri-dish cell culture with rigid surfaces and in vivo findings.

Acute bacterial endophthalmitis after cataract extraction

In order to evaluate the results, we reviewed all 34 patients treated in our hospital for endophthalmitis after cataract surgery between January 1994 and January 1998. After cultures were taken, all patients received intraocular, subconjunctival and topical vancomycin and ceftazidime. Additionally, twelve patients received the same antibiotics systemically. Besides steroids were administered in all patients. In 79% of the patients the bacterial culture was positive. Coagulase negative Staphylococcus was the most frequently isolated microorganism (48%). After treatment a visual acuity of 0.1 or more was achieved in 62% of the patients. The best final results were achieved in the patients with an initial visual acuity of 1/300 or more, and in the patients from whom a coagulase negative Staphylococcus was isolated.