bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent advances in the analysis of non vascular features in retinal images
Authors: RUGGERI A , FIORIN D 
Published: October 2007

Abstract Purpose: To problem of detecting non vascular dark lesions (haemorrhages and microaneurysms) in retinal images for diagnostic purposes is addressed. Methods: The green channel of images is extracted and then normalized by compensating the luminosity and contrast drifts. The detection of clusters of dark pixels is based first on a local thresholding to identify pixels darker than the surrounding, followed by an evaluation of their spatial density, which tells how much the neighborhood of the pixel is dense of similar (dark) pixels. A further threshold is then applied to this density to identify candidate clusters of dark pixels. Results: In a pool of 60 50‐deg fundus images acquired on slide, and then digitized with a 1378 dpi resolution, true colour, 6 images presented microaneurysms or haemorrhages. These images were chosen to evaluate the performance of the proposed method. On average, the algorithm was able to detect at least part of a lesion for 94% of the lesions present in an image. When an image presented only one lesion, so that a hit‐or‐miss situation may compromise the clinical evaluation, the algorithm was able to correctly identify the true candidate. Conclusions: A novel, high sensitivity algorithm for identifying dark lesions in retinal images is presented. It exploits both the local gray‐level information for a first segmentation and the spatial density of segmented pixels to obtain a measure of a region homogeneity. The effectiveness of the algorithm has been successfully tested on six retinal images presenting dark lesions of various shapes and dimensions. This suggest that it can be well suited as first stage of a dark lesion detection system, which will be followed by a classification stage, able to reject possible false candidates.
Advances in the detection of the retinal vasculature
Authors: HUNTER A , AL DIRI B 
Published: October 2007

Abstract Purpose: The detection and measurement of retinal vessels is discussed. Methods: A model based on fitting “ribbon of twin” active contour models, that sandwich the vessel edges between contours pulled together by forces, is used. The use of these twins, with a constraining force maintaining approximate vessel width, serves to avoid errors instituted by a variety of noise sources. Results: The method detects vessel segments with high reliability, and is able to measure the vessel width to within sub‐pixel accuracy. We present results comparing the performance with reference standard measurements constructed by a number of human assessors. Conclusions: Retinal vascular measurements are potentially extremely useful in the diagnosis of a number of disease.
Retinal pigment epithelial cells under oxidative stress
Authors: WELGE‐LUSSEN U 
Published: October 2007

Abstract Purpose: Various studies have demonstrated that cellular senescence may be accelerated by stress factors such as oxidative stress and transforming growth factor‐beta (TGF‐ß). This phenomenon has been termed ‘stress‐induced premature senescence (SIPS). The goal of the present study was to determine whether oxidative stress and TGF‐ß might induce SIPS in cultured human retinal pigment epithelium (RPE) cells. Methods: Cultured human RPE cells were exposed to hydrogen peroxide (H2O2). Additionally, cells were treated with 1 ng/ml TGF‐ß1 and ‐ß2 for 48 hours. Senescence‐associated beta‐galactosidase (SA‐ß‐Gal) activity was detected by histochemical staining. Expression of SA genes apolipoprotein J (Apo J), Connective Tissue Growth Faktor (CTGF), fibronectin, SM22 were examined by real‐time PCR. Senescence‐associated signal transduction proteins (p16, p21, pRb) were analyzed by western‐blotting. Levels of TGF‐ß1 and ‐ß2 were analyzed by real‐time PCR analysis and ELISA. The effect of TGF‐ß blocking on the oxidative stress‐induced expression of senescence‐associated biomarkers was investigated by with neutralizing antibodies against pan‐TGF‐ß and TGF‐ßII receptors. Results: H2O2 increased SA‐ß‐Gal activity by up to 10 fold and the expression of SA genes by 3‐4 folds. Treatment with TGF‐ß1 and ‐ß2 showed similar fold changes. H2O2 and TGF‐ß 1 and TGF‐ß2 markedly enhanced the expression of p16 and p21. Parallel there was an downregulation of pRb expression. Neutralizing antibodies against prevented the oxidative stress‐mediated elevation of SA biomarkers. Conclusions: Oxidative stress and TGF‐ß are capable to induce SIPS in cultured human RPE cells. Therefore, reduction of oxidative stress and minimizing TGF‐ß may help to prevent SA changes in the RPE of early AMD
Proteolysis in RPE cells
Authors: KAARNIRANTA K 
Published: October 2007

Abstract Purpose: Most cellular proteins are continuously synthesized and degraded within the life‐span of a cell. Two major systems take care of protein degradation in eukaryotic cells: the proteasomes, which degrade the vast majority of long‐ and short‐lived normal and abnormal intracellular proteins and the lysosomes, which degrade membrane and endocytosed proteins. Macroautophagy, microautophagy or chaperone‐mediated autophagy are the principal forms of lysosomal degradation in mammalian cells. In macroautophagy, cytoplasmic structures are degradated within an autophagosomes. Connection of stress inducible Hsp70, lysosomes and proteasomes were evaluated in the protein aggregation in human RPE cells. Methods: Western blotting, immunofluorescence, transmission electron microscopy, confocal microscopy, hsp70 mRNA interference, GFP‐Hsp70 overexpression techniques were used to study proteolysis in ARPE‐19 cells. Results: MG–132 proteasome inhibitor caused robust accumulation of Hsp70 protein and Ub protein conjugates in ARPE–19 cells. At both the Hsp70 and Ub colocalized with the protein aggregates. The granulation of juxtanuclear aggregation was clearly increased in response to proteasome inhibition and simultaneous hsp70 mRNA interference. Interestingly, we found that juxtanuclear protein aggregation is an interim, because a cease of proteasome inhibition leads to autophagosome‐mediated cleaning of cytoplasmic protein aggregates. The Hsp70 colocalization was observed in both primary lysosomal fractions and in autophagosomes. Conclusions: The Hsp70 molecular chaperone, lysosomes and protesomes are connected each other in macroautophagy –mediated proteolysis in human RPE cells.
The role of electrophysiology
Authors: HOLDER GE 
Published: October 2007

Abstract Purpose: To demonstrate the role of electrophysiological assessment in the investigation and management of the patient with photophobia, or whose vision is worse under bright lighting conditions. Methods: The ISCEV standard techniques for ERG, PERGm, mfERG and EOG recording will be described. Results: Selected cases will be used to illustrate the value of the objective data provided by electrophysiology. Conclusions: The objective data provided by electrophysiological assessment is important to the assessment, diagnosis and management of this group of patients.
Application of structured illumination techniques to corneal microscopy
Authors: REQUEJO‐ISIDRO J , PEREZ‐ESCUDERO A , MARCOS J 
Published: October 2007

Abstract Purpose: The microscopic study of corneal structures has always been a challenge for ophthalmologists and researchers. The inherent transparency of the cornea and the strong out‐of‐focus background are the main obstacles for achieving high‐contrast images. In the past few years traditional approaches based on the confocal principle have benefited enormously from the advances in scanning and detection technologies, but at the expense of an increasing complexity. Methods: As an alternative approach to the confocal principle, the use of different patterns (structured) of illumination to retrieve the in‐focus features in an image may be advantageous for in‐vivo imaging. It has been shown that structured illumination (SI) microscopy allows optical sectioning with at least the same resolution as standard confocal microscopy. Image acquisition is potentially faster, as optical sections of the whole field of view are obtained after acquisition of two or three widefield images rather than scanning every point in the field of view. In spite of it, the overall performance of these techniques may be affected by noise features that are particular to SI imaging. Results: We report on the application structured‐illumination microscopy to the field of ocular microscopy. To the best of our knowledge, this is the first time that corneal microscopy using structured illumination has been demonstrated. Enucleated porcine eyes have been used to study SI‐specific noise behaviour. Its implications for ophthalmic SI microscopy will be discussed.
Motion of the scattering sites in the ocular fundus during transpupillary thermotherapy
Authors: ROVATI L , CATTINI S , VIOLA F , STAURENGHI G 
Published: October 2007

Abstract Purpose: Our aim was to detect motion of scattering sites during transpupillary thermotherapy (TTT) using diffusing‐wave‐spectroscopy technique Methods: The experiment was performed on a rabbit fundus. Motion of scattering sites in the fundus was monitored during TTT. A contact lens was used for easy fundus observation and guidance of the treatment and probe laser radiation. The treated area diameter was ± 4 mm. The optics of the diffusing‐wave‐spectroscopy system were integrated into a standard ophthalmic microscope to allow a real time recording of the intensity of the light scattered by the heated scattering centres.Immediately before, uring (at 5 sec intervals) and after TTT, autocorrelation functions were acquired To exclude possible visible alteration of the tissues at the end of the treatment, an ophthalmologist observed the eye fundus. Results: The experiment showed that in the retina and RPE, temperature‐induced scatterers motion increases monotonically during TT according to an exponential trend with time constant of ± 20 seconds. The choroidal diffusion coefficient showed a clear sharp step‐down in response to temperature rise. This trend does not reflect the trend of temperature but different boundary conditions or optical properties of the scatterers.Data showed also a slight increase in choroidal blood velocity upon heating of the fundus. Conclusions: These experiments showed the ability of the system to detect motion of scattering sites in the ocular fundus layers. We observed the temperature induced dynamics of retina and choroid scattering centers. Speculatively, the choroidal diffusion coefficient trend could be related to a resctriction of the choroidal vasculature in response to increasing fundus temperature
An overview of the pathogenesis of glaucomatous optic neuropathy
Authors: GUNGOR K 
Published: October 2007

AbstractGlaucoma, clinically, is characterized by degeneration of the optic nerve and progressive visual field loss, associated with elevated intraocular pressure (IOP). The exact cause of glaucomatous optic neuropathy is not well established, although many risk factors have been determined including elevated IOP, family history, race, age, systemic diseases and myopia. Elevated IOP is the most investigated factor among others because it is the main well‐known treatable one for glaucoma.The primary components of glaucomatous optic neuropathy are spesific changes in the optic nerve head and in the retina. In the optic nerve head, these can be classified as axonal and non‐axonal effects (alterations in extracellular matrix and astrocyte ). In the retina, retinal ganglion cells appear to undergo morphologic changes before cell death.These changes give a result as an decrease in number of retinal ganglion cells and a decrease in visual acuity.Nowadays, lowering IOP alone is not sufficient for the long‐term stabilization of visual functions in glaucoma patients. Some abnormalities in optic nerve head and retina may affect relative susceptibility to IOP and explain progressive optic nerve damage and visual field loss, although adequate IOP control. Moreover, optic disc excavation and nerve fiber layer losses of up to 40% have been shown to occur, prior to visual field loss has been determined.In addition to vascular and mechanical theory for glaucomatous optic neuropathy include excitotoxic damage, insufficiency in neuron growth factors, immune‐mediated neuron destruction, and oxidative stress. The exact role of these factors and their effects on glaucomatous damage and apoptosis is still controversial.
Optic nerve injury models in the rat
Authors: TUGLU I 
Published: October 2007

AbstractGlaucoma is a degenerative disorder of the optic nerve which can be secondary to many diseases and the pathology occurs at the optic nerve head (ONH). It is important to know the effects of cell types, cell interactions, the trophic factors, receptors, channels, and matrix molecules in glaucoma. Research on the optic nerve in rats, mice, and nonhuman primates are necessary not just neurons in retina and optic nerve but also in central nervous system.Experimentally‐induced animal models help in understanding how retinal ganglion cells (RGC) die and how ON take place in this process. Special care must be taken to select controls and to use adequate number of animals. Experiments should be performed to understand the mechanism of pressure‐induced optic nerve damage and protect the optic nerve in glaucoma. An effective model should allow for the obstruction of aqueous humor outflow in order to raise IOP and for monitoring of intraocular pressure. Raised intraocular pressure, altered ocular perfusion, loss of auto regulation, alteration of vascular structure and characteristics of the blood‐brain barrier at the optic disc are alsopossible candidates in the pathogenesis of glaucoma. Animal studies indicate a response inoxidative metabolism to varied IOP and mean arterial blood pressure, and that low blood pressure leads to loss of autoregulation and ischemia of the optic nerve head.A number of techniques for increasing the intraocular pressure in rat are available. One of them involves sclerosing the trabecular meshwork using hypertonic saline. By cannulating theveins and injecting the corrosive saline retrogradely into the canal of Schlemm, it is possible to scar and close up the trabecular meshwork. Intraocular pressure elevates in approximately a week and lesions begin to develop. The lesions seen in the rat optic nerve following this procedure includes a decrease in axon density and an increase in vesicular bodies and vacuoles that is most prominent in the superior region of the optic nerve.We also carried out different models of rat studies either by damaging the ON mechanically or by ischemia to show the histological alterations in the ONH and retina. We also investigated the effects of oxidative stress and apoptosis on these alterations. Understanding the mechanism of nerve damage in these different models may provide new insights into the pathogenesis of human glaucoma.
Electrophysiology as a diagnostic tool
Authors: HOLDER GE 
Published: October 2007

Abstract Purpose: To describe the use of electrophysiological investigation in the assessment of patients with inherited retinal disease. Methods: The techniques used to elicit ISCEV Standard ERGs, PERG, EOG and mfERG will be discussed. In addition, reference will also be made to additional techniques such as ON‐/OFF‐ response recording and S‐cone ERGs Results: Selected cases will be used to illustrate the value of electrophysiological investigation in the assessment and characterisation of inherited retinal disease. Particular emphasis will be placed on those disorders where the diagnosis is made by electrophysiology. Conclusions: The objective assessment of retinal, macular and RPE function using electrophysiological techniques is indispensable to the running of an inherited retinal disease clinic. Electrophysiology is likely to be the "gold‐standard" outcome measure in studies of potential therapeutic interventions
Preoperative assessement before surgery of the lacrimal pathway
Authors: ELOY P , LEVECQ L 
Published: October 2007

Abstract Methods: Dacryocystorhinostomy (DCR) consists of diverting the lacrimal flow into the nasal cavity through an opening made surgically in a standard fashion at the level of the frontal process of the maxilla. Indication for surgery is low obstruction of the lacrimal pathway resistant to the medical treatment.To make the differential diagnosis between hypersecretion and epiphora, a high or a low obstruction, an anatomical or a functional obstruction of the lacrimal pathway, a preoperative evaluation of all the lacrimal pathway is mandatory.The authors present their experience and comment the technique, the advantages and limits of different investigations such as the ophthalmological examination including Jones tests 1 and 2, and seringing, dacryography, dacryoscan, scintigraphy of the lacrimal pathway and also give some words about the endoscopy of the lacrimal pathway. They also present the results of a survey conducted among the Belgian ophthalomologists confirming that only a minority of them perform a series of investigations (imaging) before a DCR.
Combined surgery: endoscopic transcanalicular DCR and balloondilatation technique
Authors: JAVDANI Z , ADAM J , MEYER R , EMMERICH KH 
Published: October 2007

Abstract Purpose: Combined surgery technique for high rate percentage of success in trans‐canalicular dacryocystorhinostomy or a balloon dilatation technique alone. Methods: In this approach, transcanalicular endoscope with micro drill performing surgery like usual, dilatation of the opened channel with balloon dilatation and following injection of Healon‐5 in the lacrimal duct are employed to reduced the risk of failure. This method is investigated through the two cases. Percentage of success of balloon catheter overall is estimated between 25% to 90% depends on the partial or complete obstruction. In the most of these cases of failure, cannulation was not possible because of complete obstruction. This problem might be solved by using micro drill before balloon dilatation technique. Results: In 2 cases, no more epiphora after 6 months follow‐up were observed. (100 % of success rate was achived by 2 patients). However, more cases are needed to show the real succes rate. Conclusions: Performing transcanalicular DCR using micro drill and following balloon dilatation of the naso‐lacrimal duct following an injectable product like Healon‐5 or healon‐gv (by which will hold the nasolacrimal duct open and will stay in the duct for a short period) can diminish the failure of balloon dilatation technique. In this way, the forming of synechia in all the duct from the punctum to the end of the distal duct will be reduced.
Glare as parameter of quality of sight
Authors: TASSIGNON MJ , ROZEMA JJ 
Published: October 2007

AbstractThe concept of glare, as determined by the Oculus C‐Quant device, is discussed in detail. Its clinical use and limitations are highlighted and correlations with other ocular parameters are investigated. As illustration the use of the C‐Quant in the University Hospital Antwerp for cataract and refractive cases is given, as well as for more challenging cases (postoperative complications, perforations ...).
Experimental models of ocular inflammation: an overview
Authors: BODAGHI B 
Published: October 2007

AbstractSince the description of the role of different retinal antigens associated with intraocular inflammation in the early 70’s, a great number of experimental models have been developed in order to evaluate the pathophysiology of this auto‐inflammatory condition but also the efficacy of different therapeutic strategies. Experimental autoimmune uveitis is the most common murine model which has been used for these purposes. Disease development is mediated by Th1 CD4 cells specific for various retinal autoantigens. However, the role of these cells in the pathogenicity of uveitis remains poorly understood, because it is difficult to follow their activation and migration. Activatedmacrophages, attracted by cytokine secretion, also cause retinal damage due to the release of cytotoxic oxygen and nitrogen metabolites, cytokines, and proteolytic enzymes.Even though different issues have been raised and major advances have been achieved, we are still lacking well‐defined and appropriate relevance of these models for different human conditions. This is the main difficulty encountered by the research groups who try to use experimental models for the understanding and treatment of specific human entities. Only acute uveitis is obtained in the majority of classical models in rodents. Only a few models, in which a specific antigen may trigger the auto‐inflammatory reaction without other associated factors, are available.It is highly important to revisit the experimental models of ocular inflammation in order to define the most appropriate ones for each human entity.
Prognostic tools for visual acuity in primary rhegmatogenous retinal detachment
Authors: ROLDAN‐PALLARES M , MUSA AS , BRAVO‐LLATAS C , HERNANDEZ‐MONTERO J , FERNANDEZ‐DURANGO R 
Published: October 2007

Abstract Purpose: To study the influence of central retinal artery (CRA) blood velocities, intraocular pressure (IOP) and Endothelin‐1 (ET‐1) on visual acuity (VA) of primary rhegmatogenous retinal detachment (RD) Methods: This is a prospective interventional clinical study of 66 patients undergoing scleral buckling (SB) procedure, with reattachment of the retina 8 months after surgery.CRA Doppler sonography parameters and IOP were measured before SB. Immunoreactive (IR) ET‐1 was assayed (radioimmunoassay) in plasma and subretinal fluid (SRF). Snellen VA and fundus examination were checked before and 8 months after surgery. Stepwise multivariate linear regression analysis allowed us to find models for VA Results: IOP and CRA end diastolic velocity (EDV) explains preoperative VA (R2=0.509, p<0.0001). Preoperative VA, existence of PVR, CRA EDV and plasma IR‐ET‐1 (in PVR) explains postoperative VA (R2=0.908, p<0.0001). But, preoperative VA, SRF IR‐ET‐1 and plasma IR‐ET‐1 improves last model in PVR Conclusions: Preoperative VA, existence of PVR and CRA EDV explains 90% (88% in PVR) of the variability of postoperative VA, but a model with preoperative VA, SRF IR‐ET‐1 and plasma IR‐ET‐1 explains 90% of it in PVR(Supported by grants: FIS PI 040446 and DGES 97/0028)
Disruption of binocular vision following cataract surgery
Authors: WHITE JES 
Published: October 2007

Abstract Purpose: The aim of this study was to assess the incidence of disruption of binocular vision following cataract surgery and to re‐evaluate the role of Orthoptists in pre‐assessment clinics for cataract surgery. Methods: A retrospective study was carried out of all patients who attended the hospital for cataract surgery between January 2003 and December 2003. The incidence of ocular motility disorders and diplopia which had been recorded in the case notes was noted pre‐operatively, two weeks post operatively and if it was still persisting more than six weeks post operatively. All patients with persistent diplopia/symptoms related to disruption of binocular vision had been referred for Orthoptic assessment. Results: In the period from January‐December 2003 2147 patients had cataract surgery, 93% of whom had surgery under local anaesthesia. There was a total of 17 (0.8%) cases with persistent disruption of binocular vision post cataract surgery. The aetiology of the binocular problems was divided into three groups 1)refractive, 2)pre‐existing deviation and 3)induced deviation. Treatment was by means of prisms, refractive correction, occlusion, Botulinum toxin and surgery. Conclusions: The incidence of disruption of binocular vision in those patients undergoing cataract surgery is not high. However the symptoms that they have can be very difficult for the Orthoptist to eliminate despite a range of treatment modalities. The Orthoptist therefore has an important role in pre‐assessment cataract surgery clinics in highlighting those patients in which there are potential binocular complications.