Human retinal Müller cells synthesize collagens of the vitreous and vitreoretinal interface in vitro

Purpose: To investigate the capacity of cultured Muller cells to synthesize collagens, since previous studies indicated that Muller cells could be involved in collagen remodeling at the vitreoretinal border in adult human eyes. Methods: Spontaneously immortalized cultured human Muller cells were analyzed for the presence of mRNA of types I-VII, IX, XI, and XVII collagen by RT-PCR. Furthermore, Muller cells were immunocytochemically stained for light microscopic (LM) evaluation of these collagens and their main characteristics. Finally, cell extracts and culture medium were evaluated by western blot (WB) analysis using anticollagen antibodies. Results: Cultured Muller cells contained mRNA for types I-VII, IX, and XI collagen, but not for type XVII collagen. LM and WB confirmed the intracellular expression of all the above-mentioned collagens with the exception of type XVII. Collagen secretion into the medium was established for types I-VII, IX, and XI collagen. Conclusions: Cultured Muller cells can synthesize internal limiting lamina and vitreous collagens. Possible collagen production by Muller cells could explain and expand on previous in vivo morphological findings in the embryonic and postnatal period and in pathologic conditions

Influence of wear and overwear on surface properties of etafilcon A contact lenses and adhesion of Pseudomonas aeruginosa

PURPOSE. To determine changes in physicochemical surface properties of contact tenses (CLs) during daily wear and effects of lens wear on adhesion of a Pseudomonas aeruginosa strain from a patient with CL-related keratitis.METHODS. Ten new CL wearers used ionic, etafilcon A lenses with 58% water on both eyes for approximately 10 hours each day during 10 and 50 days. All lenses were treated daily with an appropriate lens care solution. After the CLs were worn for 10 days (first pair of lenses) and 50 days (second pair, representing overwear), hydrophobicity by water contact angles, surface roughness by atomic force microscope, elemental surface composition by x-ray photoelectron spectroscopy (XPS), and adsorbed proteins by SDS-PAGE were determined on one lens. The lens from the contralateral eye was placed in a parallel plate flow chamber for bacterial adhesion after each time interval.RESULTS. Water contact angles on lenses changed from 45degrees on unused lenses to 61degrees +/- 25degrees after 10 days of wear and changed significantly (P &lt;0.05) to 27degrees +/- 14degrees after 50 days of wear. Surface roughness increased significantly (P &lt;0.05) from 4 +/- 2 nm (unused) to 10 +/- 7 nm after 50 days of wear. These changes were accompanied by adsorption of proteinaceous material, as evidenced by XPS and SDS-PAGE, demonstrating adsorption of lysozyme, tear lipocalin, and a 30-kDa protein. Initial bacterial adhesion to worn CLs was lower than to unworn CLs. Furthermore, detachment of adhering bacteria from worn lenses was easier than from unworn lenses. The changes observed in the physicochemical surface properties of the lenses after the CLs were worn for 50 days were accompanied by reports of discomfort by 6 of the 10 new CL wearers. Multiple regression analysis revealed that the most predictive variables for an effect on initial deposition after 10 days of wear were hydrophobicity, roughness, the presence of nitrogen-rich material, including the presence of a 30-kDa protein, and the presence of oxygen-rich material-that is, the type of oxygen adsorbed (O==C or O-C). After 50 days of wear, roughness and the presence of tear lipocalin were most predictive.CONCLUSIONS. This study demonstrates that the physicochemical surface properties changed after wear and overwear, whereas overwear of the lenses decreased initial adhesion of P. aeruginosa #3 under the present experimental conditions.</p

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. (Invest Ophthalmol Vis Sci. 2011;52:2565-2570) DOI:10.1167/iovs.10-639

Postoperative Metamorphopsia in Macula-Off Rhegmatogenous Retinal Detachment:Associations with Visual Function, Vision Related Quality of Life, and Optical Coherence Tomography Findings

To evaluate postoperative metamorphopsia in macula-off rhegmatogenous retinal detachment (RRD) and its association with visual function, vision related quality of life, and optical coherence tomography (OCT) findings.45 patients with primary macula-off RRD were included. At 12 months postoperatively, data on metamorphopsia using sine amsler charts (SAC), best corrected visual acuity (BCVA), letter contrast sensitivity, color vision (saturated and desaturated color confusion indexes), critical print size, reading acuity, the 25-item National Eye Institute Visual Functioning Questionnaire (NEI-VFQ-25), and OCT, were obtained.Metamorphopsia was present in 39 patients (88.6%), with most of them (n = 35, 77.8%) showing only mild metamorphopsia (SAC score = 1). Patients with metamorphopsia had significantly worse postoperative BCVA (p = 0.02), critical print size (p<0.0005), and reading acuity (p = 0.001) compared to patients without metamorphopsia. Other visual function outcomes and NEI-VFQ-25 overall composite score were all also somewhat lower in patients with metamorphopsia, but this did not reach statistical significance. No association with OCT findings was present.The prevalence of postoperative metamorphopsia in macula-off RRD patients is high, however, the degree of metamorphopsia is relatively low. When metamorphopsia is present, visual functions seem to be compromised, while vision related quality of life is only mildly affected

Bacterial transmission from contact lenses to porcine corneas:An ex vivo study

PURPOSE. To quantify the transmission to ex vivo porcine eyes of Staphylococcus aureus 835 and Pseudomonas aeruginosa 3 from three types of contact lenses - one daily wear and two extended wear - differing in hydrophobicity and roughness. METHODS. One daily wear lens (etafilcon) and two extended-wear lenses (one lotrafilcon A and one balafilcon A) were inoculated in a bacterial suspension for 30 minutes and then placed on ex vivo porcine eyes. After 16 hours of contact between lens and eye, confocal laser scanning microscopy was used to determine the number of bacteria on the lens and cornea for the calculation of transmission percentages. RESULTS. Transmission percentages were significantly different for both bacterial strains from an etafilcon A lens and balafilcon A lens (P = 0.006 and 0.04, respectively). Percentages varied from 51% to 68% for the hydrophobic P. aeruginosa and from 54% to 82% for the hydrophilic S. aureus strain, depending on the contact lens involved. Both strains were transferred the least from the most hydrophilic and roughest lens made of lotrafilcon A, although the difference was only statistically significant for S. aureus. CONCLUSIONS. Bacterial transmission to the porcine cornea differed in the various types of contact lenses and was least in the hydrophilic and rough lens type

Collagen distribution in the human vitreoretinal interface

PURPOSE. To evaluate the presence of collagen types I to VII, IX, XI, and XVIII at the posterior pole, the equator and the preequatorial area in human donor eyes, since collagens are important macromolecules that contribute to vitreoretinal adhesion at the vitreoretinal interface. METHODS. Freshly isolated human retinectomy samples from the equator were used for reverse transcription-polymerase chain reaction to detect mRNA of the above-mentioned collagens. In addition, human donor eyes and equatorial retinectomy samples were embedded in paraffin, stained with antibodies against the collagens and evaluated by light microscopy (LM). RESULTS. Retinectomy samples expressed mRNA of all tested collagen types. By LM, vitreous cortex was positive for collagen types II, V, IX, and XI. In all three regions within the donor eyes and in the retinectomy samples, the internal limiting membrane (ILM) showed types IV, VI, and XVIII; the retinal vasculature was positive for types I to VI and XVIII in most specimens; and the retinal layers showed condensed spots of type VII. In addition, type VII increased in density and in distribution over the retinal layers toward the posterior pole. CONCLUSIONS. Staining patterns of collagen types I to V, IX, XI, and XVIII confirmed previous observations. Important new findings include the presence of type VI in the ILM and type VII in several layers of the retina. Both collagens can anchor matrix components, and type VI could be involved in vitreoretinal attachment. Furthermore, the presence of collagen mRNA in human retinectomy samples may be an indication of postnatal collagen production by retinal cells

Enzymatic Breakdown of Type II Collagen in the Human Vitreous

PURPOSE. To investigate whether enzymatic collagen breakdown is an active process in the human vitreous. METHODS. Human donor eyes were used for immunohistochemistry to detect the possible presence of the matrix metalloproteinase (MMP)-induced type II collagen breakdown product col2-3/4C-short in the vitreous. Western blot and slot blot analyses were used to further identify vitreal type II collagen breakdown products in three age groups with average ages of 25, 45, and 65 years. Purified type II collagen was cleaved by MMPs that are known to occur naturally in the vitreous to elucidate what possible type II collagen breakdown products could thus be formed in the human vitreous. RESULTS. By means of both immunohistochemistry and slot blot analysis, col2-3/4C-short was detected in the vitreous. Using Western blot analysis, a range of type II collagen breakdown products was found, mostly in younger eyes, but none of these products contained the neoepitope that characterizes the col23/4C-short molecule. Digestion of purified type II collagen by MMPs did not give the same breakdown products as found in the vitreous. CONCLUSIONS. The presence of collagen degradation products in the human vitreous supports the hypothesis that enzymatic breakdown is most likely an active process in this extracellular matrix. Based on the size of the degradation products found by Western blot analysis, it is likely that in addition to MMPs, other proteolytic enzymes able to digest type II collagen are also active. (Invest Ophthalmol Vis Sci. 2009; 50: 4552-4560) DOI:10.1167/iovs.08-312

Postoperative Vision-Related Quality of Life in Macula-Off Rhegmatogenous Retinal Detachment Patients and Its Relation to Visual Function

To determine the vision-related quality of life (VR-QOL) after surgery for macula-off rhegmatogenous retinal detachment (RRD) in relation to visual acuity, contrast acuity, and color vision.In a prospective observational study, we included 55 patients with a macula-off RRD. Best corrected visual acuity (BCVA), color vision (saturated and desaturated color confusion indices (CCI)) and contrast acuity were measured at 12 months postoperatively in both the RRD eye and the fellow control eye, and the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) was filled out.Operated and fellow control eyes differed significantly in mean LogMAR BCVA (P<0.0001), median Log contrast acuity (P<0.0001), saturated CCI (P = 0.009), and desaturated CCI (P = 0.016). Significant correlations were observed between the NEI VFQ-25 overall composite score and postoperative LogMAR BCVA (R = -0.551, P<0.0001), contrast acuity (R = 0.472, P<0.0001), saturated CCI (R = -0.315, P = 0.023), and desaturated CCI (R = -0.283, P = 0.044).A lower VR-QOL was highly correlated to a worse postoperative BCVA and contrast acuity and to a lesser extent to color vision disturbances

Physico-chemistry of bacterial transmission versus adhesion

Bacterial adhesion is a main problem in many biomedical, domestic, natural and industrial environments and forms the onset of the formation of a biofilm, in which adhering bacteria grow into a multi-layered film while embedding themselves in a matrix of extracellular polymeric substances. It is usually assumed that bacterial adhesion occurs from air or by convective-diffusion from a liquid suspension, but often bacteria adhere by transmission from a bacterially contaminated donor to a receiver surface. Therewith bacterial transmission is mechanistically different from adhesion, as it involves bacterial detachment from a donor surface followed by adhesion to a receiver one. Transmission is further complicated when the donor surface is not covered with a single layer of adhering bacteria but with a multi-layered biofilm, in which case bacteria can be transmitted either by interfacial failure at the biofilm-donor surface or through cohesive failure in the biofilm. Transmission through cohesive failure in a biofilm is more common than interfacial failure. The aim of this review is to oppose surface thermodynamics and adhesion force analyses, as can both be applied towards bacterial adhesion, with their appropriate extensions towards transmission. Opposition of surface thermodynamics and adhesion force analyses, will allow to distinguish between transmission of bacteria from a donor covered with a (sub)monolayer of adhering bacteria or a multi layered biofilm. Contact angle measurements required for surface thermodynamic analyses of transmission are of an entirely different nature than analyses of adhesion forces, usually measured through atomic force microscopy. Nevertheless, transmission probabilities based on Weibull analyses of adhesion forces between bacteria and donor and receiver surfaces, correspond with the surface thermodynamic preferences of bacteria for either the donor or receiver surface. Surfaces with low adhesion forces such as polymer-brush coated or nanostructured surfaces are thus preferable for use as non-adhesive receiver surfaces, but at the same time should be avoided for use as a donor surface. Since bacterial transmission occurs under a contact pressure between two surfaces, followed by their separation under tensile or shear pressure and ultimately detachment, this will affect biofilm structure. During the compression phase of transmission, biofilms are compacted into a more dense film. After transmission, and depending on the ability of the bacterial strain involved to produce extracellular polymeric substances, biofilm left-behind on a donor or transmitted to a receiver surface will relax to its original, pre-transmission structure owing to the viscoelasticity of the extracellular polymeric substances matrix, when present. Apart from mechanistic differences between bacterial adhesion and transmission, the low numbers of bacteria generally transmitted require careful selection of suitably sensitive enumeration methods, for which culturing and optical coherence tomography are suggested. Opposing adhesion and transmission as done in this review, not only yields a better understanding of bacterial transmission, but may stimulate researchers to more carefully consider whether an adhesion or transmission model is most appropriate in the specific area of application aimed for, rather than routinely relying on adhesion models