bluuebunny/crossref_metadata_2025_split huggingface dataset:
A numerical model of the eye for simulation of corneal surgery and corneal biomechanical properties
Authors: DEL BUEY MA , LANCHARES E , CRISTOBAL BESCOS JA , CALVO B , ASCASO FJ , PALOMINO C , LAVILLA L , DOBLARE M 
Published: November 2010

Abstract Purpose To obtain a numerical model of the ocular globe in order to simulate different corneal surgery techniques and to measure changes in geometry and mechanical properties of the cornea. Methods A biomechanical Finite Element model was created with the geometry of the anterior half of the ocular globe. Each part (cornea, limbus and sclera) has different material properties, and behaviours as hyperelastic anisotropic material. The reference configuration is achieved with initial stresses and then applied the mean physiological intraocular pressure (15 mmHg) during the whole simulation process. In order to validate the model, a serial of arcuate relaxing incisions (o.z. 6 mm) and limbal ones (10 mm) were simulated. One of the principal measurable biomechanical properties of the cornea, which is the Corneal Hysteresis, was also simulated with this model. Results Regarding the simulation of arcuates and limbal incisions with the model, the obtained results were similar to those stated in different nomograms and surgical in vivo outcomes. The measure of Corneal Hysteresis was reproduced with this model obtaining similar results to measures in vivo performed with the Ocular Response Analyzer (REICHERT). The model can also be useful to simulate other surgical techniques like intracorneal rings, LASIK or keratoplastia. This model is a first approach to a future one which can customize by reproducing a patient specific corneal geometry and material properties. Conclusion The model was useful to reproduce several surgical techniques and properties measures and offers a lot of possibilities for predicting effects of future surgery techniques.
Oxygen and treatment of ocular ischemic diseases
Authors: STEFANSSON E 
Published: November 2010

Abstract Purpose In ischemia, reduced blood flow results in hypoxia. Hypoxic cells make hypoxia inducible factor (HIF), which controls many of the adaptive responses of tissue to ischemia. This includes vasodilatation, production of vascular endothelial factor (VEGF) with neovascularization and leakage, and finally apoptosis and tissue atrophy. Methods If hypoxia is improved this will reduce the production of VEGF and thereby reduce new vessel formation on one hand and vascular leakage and edeam formation on the other. Several methods are available to improve retinal hypoxia, including laser treatment, vitrectomy, vasodilatory drugs such as carbonic anhydrase inhibitors in addition to breathing oxygen. These treatment methods have been studied by many research groups with invasive polarographic electrodes and optical probes as well as noninvasive oxymetry in human patients and animal subjects. Results We will review experimental and clinical studies, which confirm that oxygen tension of the retina is increased following 1. retinal laser treatment 2. Vitrectomy 3. carbonic anhydrase inhibitors Conclusion Oxygen is the natural control of VEGF. VEGF levels in the retina and other ocular tissues are affected by oxygen levels and ischeimc diseases are currently treated with methods that affect oxygen and consequently VEGF. The addition of anti VEGF drugs to oxygen directed treatment such as laser and vitrectomy further influences the oxygen‐HIF‐VEGF‐neovascularization/edema axis in ischemic retinopathies.
Regulation of retinal tissue oxygenation
Authors: POURNARAS CJ 
Published: November 2010

Abstract Purpose To evaluate the changes in the retinal oxygen partial pressure (PO2) following physiological stimuli. Methods Evaluation of either the preretinal and intraretina partial pressure of oxygen (PO2) distribution, using oxygen sensitive microelectrodes, in various animal models. Measurements were obtained during changes of the perfusion pressure, systemic hyperoxia, hypoxia, hypercapnia, carbogen breathing and following carbonic anydrase inhibitors use. Results The oxygen tension (PO2) in the inner half of the retina remains largely unaffected by moderate changes in perfusion pressure. The increase of the systemic PaO2 through breathing of 100% O2 (hyperoxia) induces endothelin (ET) mediated marked vasoconstriction of the inner retinal arterioles in both anesthetized animals and normal human subjects. The regulatory vasoconstriction maintains the PO2 in retinal tissue constant. A decrease in PaO2 (hypoxia) induces a vasodilation of the retinal arterioles through endothelium‐derived NO release. As a result, trans‐retinal PO2 profiles made during steps of systemic hypoxia have shown that the values measured in the inner retina up to half of its thickness, remain rather stable. By contrast, the PO2 values, measured close to the choroid and in the outer retina, decrease in a linear manner with the decrease of the PaO2. An increase in the PaCO2 (hypercapnia) of arteriolar blood, produces an increase in retinal blood flow and retinal tissue PO2. Intravenous injection of acetazolamide (carbonic anhydrase inhibitor) produces an increase in preretinal PO2 due to dilation of the retinal vessels Conclusion Thanks to the autoregulatory capability of the retinal circulation, the oxygen tension (PO2) in the inner half of the retina, remains largely unaffected during physiological stimuli.
Non‐invasive measurement of retinal oxygenation: principles and expectations
Authors: HAMMER M , SCHWEITZER D 
Published: November 2010

Abstract Purpose To determine oxygen saturation (SO2) of blood inside retinal vessels which is an essential measure for the estimation of oxygen supply to the tissue as well as its oxygen consumption. Methods Two‐, four‐, and multiple ‐ wavelength approaches to the non‐invasive measurement of SO2 will be discussed. The dual wavelength technique, imaging the fundus at 548 and 610 nm, showed to be most appropriate for clinical routine investigations. The SO2 of the hemoglobin in retinal arterioles and venules is calculated from the ratio of the optical densities of the vessels at both wavelengths. Results From a healthy control population, mean arterial and venous SO2 were measured to be 98±10.1% and 65±11.7% with reproducibility of 2.52% and 3.25% respectively. In a cohort of 41 patients (mean age: 65±12.3 years) with diabetic retinopathy (DR), we found an increase of the venous SO2 with the severity of DR: Mild non‐proliferative DR 69±7%, moderate non‐proliferative DR 70±5%, severe non‐proliferative DR, 75±5%, and proliferative DR 75±8%. Measurements of SO2 in accordance with vessel diameters revealed a correlation of the venous SO2 with arterial as well as venous diameters in 159 diabetic patients (mean age: 55.8±13.9 years) with no or non – proliferative DR. Increased venous SO2 is an indicator of insufficient oxygen supply to the retinal tissue. The correlation of the vessel diameters with venous SO2 may point to compensatory mechanisms of retinal blood flow regulation. Conclusion Accurate retinal vessel oximetry is possible by non – invasive optical methods. Combined with measurements characterising the retinal blood flow, it is a powerful tool for the estimation of retinal oxygen supply and consumption.
Commercial interest
Endothelial involvement indicates disease activity in Herpes simplex virus keratitis
Authors: HILLENAAR T , REMEIJER L 
Published: November 2010

Abstract Purpose Corneal endotheliitis is a potentially sight‐threatening clinical manifestation of herpes simplex virus (HSV) keratitis. Early detection and consequent treatment may prevent development of endothelial decompensation. The goal of this previously published study was to describe the morphological features, frequency, and clinical consequences of endothelial involvement in HSV keratitis as seen by in vivo confocal microscopy (IVCM). Methods We examined both eyes of 250 patients with HSV keratitis by slit‐lamp and IVCM. All examinations were assessed for endothelial deviations characteristic of endotheliitis. To determine the specificity, we reviewed our IVCM database for morphologically comparable alterations. This database included 200 healthy volunteers and 1400 patients with various corneal pathologies. The endothelial cell density (ECD) change between the first and last visits of patients with HSV keratitis was evaluated. Results Endotheliitis‐specific deviations were detected in 107 of 250 patients with HSV keratitis (43%). Pseudoguttata, enlarged intercellular gaps, infiltration of inflammatory cells into the endothelial layer, loss of defined cell boundaries, spot‐like holes, and endothelial denudation disappeared within 3 weeks with appropriate antiviral and anti‐inflammatory treatment. Alterations were non‐specific for HSV keratitis. Similar alterations were detected in adenoviral, fungal, bacterial, and acanthamoeba keratitis. The HSV affected eyes with endothelial involvement showed a mean ECD decrease of 10.3% per year. Conclusion Endothelial involvement indicates inflammatory activity in HSV keratitis and is associated with irreversible endothelial cell loss. IVCM allows early detection and follow up of endotheliitis‐specific alterations.
The presence and suggested role of mesothelial proteins in the human corneal endothelium
Authors: JIRSOVA K , MERJAVA S 
Published: November 2010

Abstract Purpose To determine whether proteins that are characteristic of the human mesothelial cell phenotype are expressed in human corneal endothelium. Methods Cadaverous human corneo‐scleral discs and pathological corneal specimens (melted and rejected corneas) were used. The detection of mesothelin, proteinase inhibitor‐9 (PI‐9), calretinin and HBME‐1 protein (a membrane protein of mesothelial cells) was performed on cryosections and corneal endothelial imprints using indirect immunofluorescent or enzymatic immuncytochemistry. The staining intensity was assessed using fluorescent or light microscopy, and the percentage of positive cells was calculated. Semi‐quantitative RT PCR of PI‐9, mesothelin and calretinin was performed using mRNA isolated from endothelial imprints. Results A strong signal for mesothelin was present in the corneal epithelium, while less intensive staining was visible in the endothelium. These results were confirmed using qRT‐PCR. Immunostaining for PI‐9 was observed in almost all corneal epithelial cells and in approximately 50% of the endothelial cells. An increased number of PI‐9‐positive cells was detected in stromal infiltrates of most melted corneal explants, while almost no positivity was observed in rejected explants. Calretinin was detected in the corneal epithelium and less intensively in the corneal endothelium, where both cytoplasmic and nuclear localisation were demonstrated. HBME‐1 antibody strongly stained the corneal endothelium and stromal keratocytes. Conclusion The proteins expressed constitutively in mesothelial cells (PI‐9, mesothelin, calretinin and HBME‐1 protein) are present in adult human corneal endothelium, confirming that this layer expresses markers typical of mesothelial cells.
Identification of potential human corneal endothelial stem‐like cell niches
Authors: THURET G , HE Z , PIPPARELLI A , PISELLI S , PEOC'H M , DUMOLLARD JM , ACQUART S , GAIN P 
Published: November 2010

Abstract Purpose to study the localization of potential stem‐(like) cells in human adult corneal endothelium Methods Fresh (6‐12h post mortem) and organ cultured (OC) corneas were studied after flat mount. The whole endothelium and posterior limbus (PL) was observed after triple staining with Trypan blue, Alizarin red and Hoechst 33342, in order to determine cells shape, localization and viability. The level of endothelial cell (EC) differenciation was determined after immunostaining (fluorescence) for ZO‐1, Na+/K+ ATPase and COX IV; the cell proliferation status was assessed using Ki67; four markers for stem cells were used: Oct‐4, BCRP, Nestin and Telomerase; ability for cell migration was evaluated from Myosin IIA expression Results In several corneas, the nuclei of peripheral EC were centripetally aligned suggesting continuous slow central migration. Numerous small cells with a reduced expression of differenciation markers were accumulated near peripheral Hassall Henle bodies. In these potential niches, cells were distributed in 3‐5 layers. A high expression of Myosin II was found in peripheral cells. Ki67+ cells were found in PL and peripheral EC only after OC. None of the 4 stem cell markers was found in EC, and their expression in PL was poorly reliable because of high background noise. Numerous trypan blue positive cells were located at the PL and in the extreme periphery of endothelium Conclusion several strong arguments suggest the location of corneal endothelial stem‐like cell niches in endothelial periphery or in the PL, and the capacity of EC to migrate from these niches toward the centre. Trypan blue staining pattern suggests that they could rapidly die in ex vivo corneas, and be therefore hard to indentify
Modulation of apoptotic signaling pathways to promote survival of endothelial cells by gene therapy
Authors: FUCHSLUGER T , JURKUNAS U , KAZLAUSKAS A , DANA R 
Published: November 2010

Abstract Purpose Corneal transplantation is the most common transplantation worldwide. Surgeons and eye banks face major problems: (1) shortage of tissue in aging populations, (2) loss of high‐quality tissue due to cell loss during storage, (3) graft failure. It has been demonstrated that EC loss is mediated by the cells’ intrinsic death machinery resulting in apoptosis. Identification of survival strategies could raise the availability of tissue, with a significant impact on transplantation by lowering graft rejection rate. The purpose of this study different apoptotic pathways and to determine the protective effect of the anti‐apoptotic proteins bcl‐xL and p35. Methods Intrinsic (mitochondria‐mediated) and extrinsic (ligand‐mediated) apoptotic pathways were selectively activated to provoke apoptosis of murine and human corneal endothelial cells suspensions and corneas. Gene transfer of bcl‐xL or p35 was accomplished, survival of EC was determined by flow cytometry and laser scanning microscopy. Results Interestingly, we were able to determine distinct differences in cell survival enhancement depending on the type of overexpressed protein. Whereas uninfected controls showed significant EC death, gene‐therapeutically treated EC demonstrated significantly increased cell survival. We will present data on the efficacy of certain anti‐apoptotic proteins in select pathways. Conclusion Exploring inhibitory strategies of EC death can lead to clinically relevant survival strategies with significant impact on corneal grafting.
Donor and recipient endothelial cell populations in transplanted corneas: new insights from endothelial imaging
Authors: LAGALI N , STENEVI U , CLAESSON M , FAGERHOLM P , HANSON C , WEIJDEGåRD B , STRöMBECK AS 
Published: November 2010

Abstract Purpose To elucidate the pattern of donor and recipient endothelial cell population in transplanted human corneas and investigate factors impacting this mosaic. Methods 36 corneal grafts were collected from recipients of opposite sex to the donor, at the time of re‐transplantation. An endothelial sheet was harvested from each graft, and labeled by fluorescent in situ hybridization of the sex chromosomes, to identify cells as donor or recipient‐derived. Images of the graft endothelium were assembled to depict the pattern of cell population of the graft, and the proportion of donor cells present was estimated. Results Endothelial cells of donor origin were found in 26 of 36 grafts, persisting up to 26 years after transplantation. The proportion of donor endothelial cells in the graft was not significantly correlated with postoperative time (P = 0.19). Endothelial images indicated a highly variable pattern of recipient cell repopulation of the graft. A tendency towards donor cell retention in transparent, successful grafts was noted; however, this feature alone was not a reliable indicator of long‐term graft transparency. Recent in‐vivo optical coherence tomography studies of transplanted corneas indicate a possible mechanism impacting the donor and recipient cell patterns observed on the endothelial surface. Conclusion Two‐dimensional imaging of the corneal graft endothelium revealed a variable pattern and extent of donor and recipient cell population, indicating the highly dynamic nature of the corneal endothelium after transplantation.
Oxidative stress in corneal limbal rings
Authors: JOHNSEN‐SORIANO S , ARNAL E , ROMERO FJ 
Published: November 2010

Abstract Purpose The aim of this work was to study oxidative stress markers in corneal limbal rings stored in Optisol at different preservation times. Methods Total Antioxidant capacity was measured with a commercial kit (Antioxidant Assay Kit, Cayman). Total nitrites were measured with a commercial kit where the amount of total nitrites was monitored spectofotometrically by reading the absorbance at 540 nm. Moreover, HNE (4‐hydroxy‐2‐nonenal) immunohistoquemistry was performed at 3 µm thick paraffin sections. Results The antioxidant capacity in corneal limbal rings preserved for 7 days were decreased significantly (0.5 ± 0.02 mM/mg prot) when compared to a fresh corneal limbal ring (1.1 ± 0.28 mM/mg prot) * p< 0.05. Moreover, the total nitrites were significantly elevated in corneal limbal rings preserved for 7 days (1.47 ± 0.18 umol/L/mg prot) when compared to fresh corneal limbal rings ( 0.89 ± 0.46 umol/L/mg prot) * p< 0.05. Immunohistoquemistry revealed that there exist an increase in HNE positive cells as conservation time increases. Conclusion Oxidative stress factors increases with time in corneal limbal rings preserved in Optisol.
Radiation‐induced lens opacities: towards a new strategy to address the low dose risk research with the European network DoReMi
Authors: GOURMELON P , JOURDAIN JR , JACOB S 
Published: November 2010

AbstractIn 2010, a Network of Excellence called DoReMi was launched by the EURATOM FP7 programme. DoReMi will act during the next six years as an operational tool for the development of a research platform devoted to low dose risk research in Europe. The research activities of DoReMi are implemented within three work packages: WP5, WP6, and WP7, which are respectively concerned with the shape of the dose effect relationship, individual radiation sensitivity and non‐cancer effects. The overarching objective of WP7 is to implement a long‐term, integrated approach involving several disciplines, namely, epidemiology, radiobiology and toxicology, for the purpose of risk evaluation for radiation‐induced non‐cancer effects. One of the operational objectives of the DoReMi WP7 consists of undertaking feasibility studies addressing the issues of vascular effects, lens opacities and cognitive effects. The presentation to be given will provide the assembly with (i) information about the European low dose risk research strategy; (ii) latest knowledge about the epidemiological evidence of radiation‐induced lens opacities; (iii) information about the feasibility study of lens opacities to be launched in a group of interventional cardiologists (iv) most promising mechanistic hypotheses for the development of radiation‐induced lens opacities recognizing that while posterior subcapsular cataracts are characteristic of an exposure to ionizing radiation, several sets of data suggest that the broader category of posterior cortical cataracts may also be regarded as radiation‐associated. Eventually the presentation will discuss the issue of a threshold for the development of radiation‐induced lens opacities and list the scientific questions raised by the radiation protection community to the vision and eye research community.
Management of iris melanomas with 125 iodine plaque radiotherapy
Authors: FERNANDES BF , KREMA H , FULDA E , PAVLIN CJ , PAYNE DG , MCGOWAN HD , BURNIER MN , SIMPSON ER 
Published: November 2010

Abstract Purpose The experience with 125Iodine (I125) plaque brachytherapy in the treatment of IM at the Princess Margaret Hospital/University Health Network is the subject of the report to follow. Methods All cases of IM submitted to I125 plaque radiotherapy were included. Patients' demographic, clinical, management, and follow‐up data were reviewed. Outcome measures included rates of tumor control, eye preservation, systemic metastases, and brachytherapy‐related complications. Results Fourteen IMs were included in the study. All patients had blue/green irises. Mean largest basal dimension and thickness were 7.1 +/‐ 2.1 mm (range, 4.0 to 11.5 mm) and 2.2 +/‐ 0.8 mm (range, 1.0 to 3.5 mm), respectively. Ten patients (71%) had seeding and 2 (14%) had glaucoma at presentation. Median follow‐up was 26.6 +/‐ 19.5 months (range, 6 to 72 months). Tumor control was achieved in 100% of the cases and no eye was enucleated because of radiation‐induced complications. At last visit, all patients were alive and free of metastasis. Final visual acuity was the same as or better than before treatment in 9 patients (75%). Cataract was the most common complication (8; 75%), followed by persistent glaucoma (2; 17%) and anterior uveitis (1; 8%). No other significant complication was seen during the follow‐up period. Conclusion Plaque radiotherapy is a safe and effective conservative treatment option for IM, although cataract is a common, yet treatable, complication. This treatment scheme circumvents an intraocular procedure and may avoid the dissemination of malignant cells, and provides a margin of safety in the treatment of clinically undetectable disease.
Lipid profile of Tenon’s capsule in glaucoma patients
Authors: BRON AM , BRETILLON L , GREGOIRE S , ACAR N , CREUZOT C 
Published: November 2010

Abstract Purpose To provide data on the lipid profile of the Tenon’s capsule in Human glaucomatous eyes and to establish possible relationships with the short term outcome of filtration surgery. Methods Fragments of Tenon’s capsule were collected during glaucoma surgery in patients suffering from open angle glaucoma (10 trabeculectomies and 17 non penetrating deep sclerectomies). The lipid profile of the human samples was determined by gas chromatography. A successful outcome after glaucoma surgery was defined by an intraocular pressure (IOP) ≤ 15 mmHg at 6 months without any IOP‐lowering agent. Results We included 27 patients (12 males, 15 females) with a mean age of 65.5 ± 12.1 years. Twenty three surgeries were successful according to our criteria. The percentages of the main fatty acids were as follows: Mean STD Range Arachidonic acid 5.33 3.66 1.00‐14.80 DHA 0.88 0.62 0.28‐2.56 Omega 3 1.86 1.05 0.55‐4.19 Omega 6 18.97 5.94 11.64‐32.89 Omega6/omega3 11.86 3.95 6.99‐23.73 The IOP before and 6 months after the surgery was 20.8 ± 7.1 mm Hg, range [13‐37] and 11.7 ± 3.2 mmHg, range [6‐18] respectively. We did not find any statistically significant correlation between PUFAs content of Tenon’s capsule, IOP at 6 months, delta IOP and surgical outcome. Conclusion Fatty acid composition of Tenon’s capsule was highly variable among patients. In this small series we failed to identify a specific PUFA profile of Tenon’s capsule as a risk factor for failure of glaucoma surgery.