bluuebunny/crossref_metadata_2025 huggingface dataset:
Microplasmin as an antiscarring agent for glaucoma surgery: translation into clinical application
Authors: VANDEWALLE E
Published: November 2010

Purpose Previously Microplasmin was investigated in a rabbit model for trabeculectomy. The combination of intracameral injections and topical drops of Microplasmin improved surgical outcome. The aqueous solution of Microplasmin used, was not optimized for use as drops or injections. Microplasmin is an autocatalytic enzyme which has a short half life when it is brought in conditions of 37°C and physiological pH. Therefore there is need for a more stable and longer acting formulation.

Methods Firstly we will do pharmacological experiments to determine the rheological characterization of drug carriers with Carrier‐med rheometer. Then we will define the purity of Microplasmin bulk drug substance by RP‐HPLC. Finally, we will check the Microplasmin activity in the new obtained solutions by spectrophotometer. Secondly we will perform trabeculectomy in a rabbit model and administer the most qualified and optimized formulations. Postoperative clinical evaluation of IOP, bleb area, conjunctival vascularity and anterior chamber assessment will be performed. The eyes will be immunohistological investigated for collagen and inflammation.

Conclusion Our previous data learned that the combination therapy of Microplasmin improved surgical outcome in a rabbit model, despite the fact that the formulation of Microplasmin was not optimized for use as drops or injections. Our proposed research project will optimize the formulation of Microplasmin for extended drug delivery and determine the optimal administration route and regimen. We believe that this project will allow us to further improve the positive animal data, translate this novel antifibrotic adjunctive therapy into clinical application, and thus improve the outcome after trabeculectomy in patients.
Clinical applications of corneal Scheimpflug densitometry in DSAEK and cornea guttata patients
Authors: WEYNS M , ROZEMA J , KOPPEN C , TASSIGNON MJ
Published: November 2010

Purpose The aim of this project is to study clinical applications of corneal Scheimpflug densitometry. In the first part of the study a correlation between corneal Scheimpflug densitometry and endothelial cell count in cornea guttata will be studied. The second part will investigate a possible correlation between the smoothness of the corneal graft and postoperative visual acuity in DSAEK patients.

Methods Cross‐sections of corneal Scheimpflug images will be analyzed by means of custom written software. Parameters such as average densitometry profile, position and intensity of the Bowman membrane and corneal endothelium peaks, as well as the position and intensity of the interface between an acceptor cornea and the DSAEK graft (if present) will be calculated.

Results The method to analyze the corneal densitometry has already been developed and tested on corneas of contact lens wearers and post refractive surgery patients. A small number of DSAEK en cornea guttata eyes have been analyzed as well, demonstrating the potential of this technique in these patients.

Conclusion Corneal Scheimpflug densitometry may be complementary to endothelial cell count in monitoring the disease progression in cornea guttata patients. Corneal Scheimpflug images may also be considered a predictor for visual outcome after DSAEK if the postoperative visual acuity variations in DSAEK patients can be linked to wrinkles in the posterior surface of the graft.
Herpetic keratitis: Herpes simplex virus versus host
Authors: VERJANS G
Published: November 2010

Herpes simplex virus type 1 (HSV‐1) is an endemic virus worldwide that causes ocular disease in a limited but significant number of infected persons. Corneal HSV‐1 infection is clinically classified into herpetic epithelial keratitis (HEK) and herpetic stromal keratitis (HSK). HEK is an acute inflammation and results from viral toxicity of infected corneal epithelial cells. In contrast, HSK is characterized as a chronic immunopathogenic disease in which tissue injury and eventually blindness is due to the complex interplay between cells of the innate and adoptive immune response to viral antigens expressed in the corneal tissue. Studies performed on the experimental HSK mouse model greatly improved our understanding of the pathogenesis of HSK. This talk will recapitulate current insights on the virus‐host interactions involved in the initiation and perpetuation of herpetic keratitis in mice and men.
Animal models of herpetic retinitis
Authors: LABETOULLE M
Published: November 2010

The Herpes simplex virus (HSV) is characterized its ability to replicate in the nervous system, before inducing a latent infection with potential reactivation. Most frequent ocular complications of recurrent HSV infection are keratitis and conjunctivitis. Less frequently, the iris and the ciliary body may also be involved (anterior uveitis). The most severe HSV ocular infection is retinitis, a rare but potentially blinding disease, due to frequent bilateral involvement. Studies on human post‐mortem tissues showed that HSV is widely distributed in the population, with a preferential location within the trigeminal ganglions (innervating the cornea), but also in the superior cervical ganglions (innervating the iris) or in brain/medullar tissues (innervating the retina). Animal models have been developed to understand the pathogenic processes that lead to this rare but devastating retinal disease. Since human is the only natural host of HSV, it is difficult to obtain a perfect animal model that perfectly mimics the disease. Several animal models, based on different inoculation procedures, are thus necessary to circumscribe the anatomical, cellular and molecular aspects that lead to retinal infection. Finally, HSV retinitis appears as a clinical condition that is highly constrained by the relationships between the strain of the virus and the immune response of the host.
Endoplasmic reticulum stress and inflammation signaling in RPE cells
Authors: SALMINEN A
Published: November 2010

Pathogenesis of AMD is linked to augmentation of cellular stress, e.g. oxidative and proteotoxic stress, hypoxia and inflammation. All these conditions trigger stress in endoplasmic reticulum (ER) and in that way can disturb the protein quality control in retinal pigment epithelial (RPE) cells. ER stress stimulates the unfolded protein response (UPR) via the activation of IRE1, PERK and ATF6 transducers. The UPR signaling can restore cellular homeostasis but chronic and overwhelming stress can induce inflammatory response via different UPR signaling pathways and lead to apoptotic cell death. Moreover, ER stress is a well‐known inducer of vascular endothelial growth factor (VEGF) expression and in AMD, ER stress could provoke neovascularization and the conversion of dry form to wet counterpart. ER stress has a fundamental role in the pathogenesis of several diseases, e.g. in diabetes and neurodegenerative diseases. This lecture will review the recent advance in understanding the inducers of ER stress, present in RPE cells during AMD, and the possible role of ER stress in evoking inflammation and neovascularization during the pathogenesis of AMD.
Update on genetics in inherited retinal disease
Authors: LEROY BP
Published: November 2010

Purpose To provide an overview of the recent developments in genetics of inherited retinal dystrophies and dysfunctions.

Methods A systematic approach, supported by case presentations, will be used to illustrate an overview of new insights into genotypes and phenotypes of generalised dystrophies and dysfunctions of the retina.

Results Much progress has been made in recent years in unravelling the molecular mechanisms underlying generalised retinal dystrophies and dysfunctions, with a wide variety of functions attributed to proteins encoded by causative genes. Identification of new genes such as PDE6C in achromatopsia and TRPM1 in autosomal recessive cCSNB provide further insight in retinal function. In addition, proven and confirmed success of gene therapy for Leber congenital amaurosis in man is leading the way for further treatment trials in humans suffering from different inherited retinal diseases.

Conclusion Rapid progress is being made in the field of genetic retinal disease, with novel developments both in genotyping and improved detailed phenotyping. In addition, gene therapy is becoming a potentially feasible treatment option for several inherited retinal conditions.
Behçet’s uveitis
Authors: TUGAL‐TUTKUN I
Published: November 2010

Abstract not provided
Study of the role of P2Y receptors in the development of experimental autoimmune uveitis
Authors: JUDICE DE MENEZES RELVAS L
Published: November 2010

Purpose During autoimmune uveitis (AU), retinal specific auto‐reactive T lymphocytes (TL) are activated, alter blood retinal barrier(BRB) and penetrate the eye where they start an inflammatory reaction. Nucleotides, normally present at low concentration in extracellular media, can act as a danger signal, through P2 receptors activation and might be implicated in AU. In this work we would like to investigate if the expression of the nucleotide receptor P2Y2 has any role in experimental autoimmune uveitis (EAU).

Methods EAU will be induced in WT and P2Y2 KO mice by IRBP peptide 1‐20 injection. 12 days later, TL from spleen and lymph nodes will be purified and restimulated by IRBP. TL proliferation will be measured by thymidine incorporation and cytokines secretion by ELISA. TL from the 2 groups of mice will also be adoptively transfered in WT mice. Similarly, TL from WT mice will be adoptively transfered in WT and P2Y2 KO mice. EAU development will be graded by clinical and histological scores.

Results TL generated in KO mice proliferate and produce less IFNγ and IL‐17, after IRBP restimulation than TL generated in WT mice. Accordingly, adoptive transfer of TL generated in KO mice induce significantly a lower grade of disease than those generated in WT mice. Finally, adoptive transfer of TL generated in WT mice induce disease of significantly lower grade in KO mice recipient than in WT mice recipient.

Conclusion Our preliminary data shows that P2Y2 KO mice have a defective immune response after immunisation and develop lower intraocular inflammation following adoptive transfer with TL. Altogether this suggests that P2Y2, as danger receptor signals, play an important role in the development of uveitis.
Safety evaluation of intravitreal use of a beta2‐agonist in rabbit eyes
Authors: VAN CALSTER J , VERSTRAETEN S , VAN GINDERDEUREN R , STALMANS I , STALMANS P
Published: November 2010

Purpose There is no known information on the use and safety of a long‐acting beta‐agonist, such as Clenbuterol when administered by intravitreal injection. Therefore, it is appropriate to perform this intravitreal injection in an animal model prior to start with a human experiment. The aim is to investigate the safety of an intravitreal injection of the beta2‐agonist Clenbuterol in rabbit eyes. This study is in preparation of using of this molecule in human eyes. That trial will be a monocentric, academic (investigator driven) trial to investigate the safety and efficacy of an intravitreal beta2‐agonist in patients with persistent subfoveal fluid after retinal detachment surgery. Approval of the ethics committee for the human trial has already been obtained, pending a re‐evaluation after the results of the animal study will be known.

Methods An intravitreal injection of 0,1 ml solution containing 0.08µg Clenbuterol or 0.1ml NaCl 0.9% was given in 10 eyes of 10 rabbits. The distribution occurred at random and was masked. A masked investigator examined both eyes after 1, 3 and 7 days (biomicroscopy, intraocular pression and ophthalmoscopy). After one week, the rabbits were sacrificed, the eyes enucleated and fixated for histopathological examination and electron microscopy by a masked investigator. Cell death was monitored by a DNase type I/II activity assay.

Results There was no clinical or histopathological difference between the clenbuterol and the control group.

Conclusion Clenbuterol is not toxic for the retina of rabbit eyes after intravitreal injection. It can be considered for the use in human eyes. Final approval of the ethics committee for the human trial is awaited.
Role of VEGF‐isoforms in pathological choroidal angiogenesis
Authors: VAN DE VEIRE S , VAN BERGEN T
Published: November 2010

Purpose The aim of this project is to study the specific role of the VEGF‐isoforms in pathological angiogenesis, and to investigate the effect of blocking a single isoform on the formation of choroidal neovascularization (CNV).

Methods Endothelial and fibroblast cell cultures were made; VEGF 12, 164 or 189 was added to study their effects. VEGF‐isoform specific mice (VEGF 120/+, VEGF 164/164 and VEGF188/188 mice) , as well as double transgenic mice (VEGF 120/164, VEGF 164/188 and VEGF120/188 mice) are used to study the role of VEGF‐isoforms in pathological angiogenesis. At first, these VEGF‐isoform specific mice were backcrossed to a C75Bl/6 background. CNV was induced by placing 3 laser spots at the 9, 12 and 3 o’clock position (100µm spot size, 0.05 s spot duration and 400mW power). Quantification of the area of newly formed blood vessels was determined by retrobulbar dextran linked FITC perfusion.

Results Preliminary data in endothelial cell and fibroblast cultures in vitro show that the VEGF121 and VEGF165 isoforms significantly the amount of angiogenesis, whereas the VEGF121 and VEGF189 isoforms play a role in fibrosis. In vivo, the same effects were checked on a fluorescent CD31 and Vimentin immunostaining of the choroids. An inhibition in neovascularization was present in all 3 isoform specific mice, but the effects were comparable. For the moment, mice colonies are being enlarged to repeat experiments and subsequently, these mice are intercrossed to obtain double transgenic mice.

Conclusion This study will shed new light on the different role and the inhibition of the VEGF‐isoforms in CNV formation during AMD. Thus, our project may open new perspectives for the treatment of various retinopathies that are known to be associated with VEGF upregulation.
Safety of the anterior vitreous detachment induced by microplasmin, pharmacologic vitreolysis to separate the posterior capsule from the anterior hyaloid
Authors: VAN LOOVEREN J
Published: November 2010

Purpose The aim of this project is to establish the safety of the use of microplasmin in the vitreolenticular interface to promote the separation of the anterior hyaloid from the posterior capsule.

Methods The safety of the use of microplasmin solution will be examined in 24 eyes of 12 rabbits after having performed a cataract surgery and a primary posterior continuous curvilinear capsulorhexis and having exposed the anterior hyaloid interface with a solution of different doses of microplasmin (125µg or 250µg in 0.1ml balanced salt solution)and having left this solution in place during different time intervals starting from 5 minutes to one hour. The rabbit eyes will be examined at well‐defined time intervals: day 1 and 7, month 1,2,3,6 and 12. Slitlamp examination and OCT‐SLO imaging will be performed to monitor ocular inflammation, visual axis reproliferation and anterior vitreous anatomy.

Conclusion Congenital cataracts, whether or not combined with persistent fetal vasculature may present different degrees of congenital dysgenesis of the vitreolenticular interface. Pharmacological separation of the interface between posterior lens capsule and anterior hyaloid would be benificial to improve the surgical outcome. Therefore the feasibility, safety and clinical application of intravitreal injection of microplasmin for this indication need to be examined first.
Are the goals of the medical director and the programme director compatible?
Authors: TASSIGNON MJ
Published: November 2010

Abstract not provided
Retinal vessel diameter affects oxygen saturation measurements
Authors: HARDARSON SH , BERGVINSSON HR , STEFANSSON E
Published: November 2010

Purpose To test whether retinal vessel oxygen saturation measurements are affected by vessel diameter and to compare saturation between the temporal and nasal retina.

Methods The Oxymap retinal oximeter is based on a fundus camera. It measures light absorbance at two wavelengths of light and calculates oxygen saturation in retinal vessels as well as vessel diameter. Measurements were performed on 12 healthy individuals. The effect of vessel diameter on saturation measurements was tested by measuring before and after the first bifurcation in the retina (1st degree parent vessels and 2nd degree daughter vessels). Arteriolar saturation can be assumed to be equal before and after bifurcation.

Results The ratio between oxygen saturation in 1st degree parent arteriole and 2nd degree daughter arteriole was 0.97±0.02 (mean±SD). The ratio was significantly lower than the theoretical value of 1.00 (p<0.001, n=12) The corresponding ratio for venules was 0.90±0.04 (p<0.001). Oxygen saturation was 94±6% in 1st degree superotemporal arterioles and 99±6% in superonasal arterioles (p=0.057). Oxygen saturation in inferotemporal arterioles was 89±6% and 95±4% in inferonasal arterioles (p=0.009). There was no significant difference in venous saturation between temporal and nasal quadrants.

Conclusion Measured oxygen saturation is lower in 1st degree parent vessels than in their 2nd degree daughter branches. This indicates that retinal vessel diameter affects oxygen saturation measurements. The higher measured saturation in the nasal arterioles, compared to temporal arterioles, may also be due to the fact that the nasal vessels are narrower. A correction for the effect of vessel diameter should be incorporated into oxygen saturation measurements.

Commercial interest
Reproducibility of retinal vessel hemoglobin oxygenation saturation in healthy subjects
Authors: LASTA M , BOLTZ A , SCHMIDL D , PALKOVITS S , PEMP B , GARHOFER G , SCHMETTERER L
Published: November 2010

Purpose Only recently systems for the measurement of hemoglobin oxygenation saturation in retinal vessels became commercially available. In the present study a fundus camera equipped with a dual wavelength transmission filter and a CCD camera was used (Imedos, Jena, Germany). Two monochromatic fundus images at 548 and 610 nm were recorded simultaneously and the oxygen saturation (SaO2) was calculated based on the optical density ratio.

Methods A study on test/retest, short‐term and day‐to‐day reproducibility of the technique was done in 14 healthy subjects. To assess test/retest variability fundus images were taken at each measurement cycle. To assess short‐term reproducibility 2 such cycles of 3 fundus images were done within 15 minutes. Finally, this cycle of measurements was done on the next day to assess day‐to‐day reproducibility. Data were evaluated separately for retinal branch arteries and branch veins. The reproducibility was calculated using the standard deviation (SD) of the measurements.

Results In retinal branch veins the SaO2 was 49±9% (range 32‐69%, 38 vessels) and in retinal branch arteries 91±8% (range 77‐112%, 40 vessels). The test/retest SD was 5.4±3.7% in retinal veins and 3.0±2.3% in retinal arteries. The short term SD was 4.7±3.7% in retinal veins and 2.9±2.1% in retinal arteries. The day‐to‐day SD was 6.2±4.1% in retinal veins and 4.0±2.8% in retinal arteries.

Conclusion Our data indicate that the test/retest, short‐term and day‐to‐day reproducibility of the technique is acceptable. Hence, the system may be adequate to follow oxygen saturation during disease processes. The data obtained in retinal branch arteries indicates, however, that the validity of measurements requires further studies.
Role of nitric oxide in optic nerve head blood flow regulation during isometric exercise in healthy humans
Authors: SCHMIDL D , BOLTZ A , LASTA M , KAYA S , PEMP B , GARHOFER G , FUCHSJAEGER‐MAYRL G , SCHMETTERER L
Published: November 2010

Purpose Nitric oxide (NO) is an important regulator of optic nerve head (ONH) blood flow in humans. We have previously shown that NO is also involved in choroidal blood flow regulation during isometric exercise. Inhibition of NO synthase (NOS) has been reported to shift choroidal pressure–flow curves during squatting to the right. The hypothesis for the present study was that inhibition of NOS may also influence ONH blood flow during isometric exercise.

Methods To test this hypothesis, a randomized, double‐masked, placebo‐controlled, three‐way crossover study was performed in 18 healthy volunteers. Subjects received on different study days intravenous infusions of NG‐monomethyl‐ L‐arginine (L‐NMMA), phenylephrine, or placebo. During these infusion periods, subjects were asked to squat for 6 minutes. ONH blood flow was assessed with laser Doppler flowmetry, and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure.

Results L‐NMMA and phenylephrine increased resting OPP (p < 0.001 versus baseline), but only L‐NMMA reduced resting ONH blood flow (p = 0.02 versus baseline). The relative increase in OPP during isometric exercise was comparable with all drugs administered (p = 0.69). In addition, the change of ONH blood flow was comparable with all administered drugs (p = 0.43).

Conclusion These data indicate that NO plays an important role in the regulation of ONH blood flow at baseline, but does not change the response of ONH blood flow during isometric exercise.
Comparison of algorithms for oximetry in vivo and ex vivo
Authors: DE BROUWERE D , DAINTY C
Published: November 2010

Purpose Several authors have proposed a number of algorithms to extract the oxygen saturation in retinal blood vessels based on multispectral image analysis. We evaluated the outcomes of seven known algorithms based on hyperspectral retinal images.

Methods Hyperspectral images are acquired using a fundus camera where a slit spectrograph is registered onto a retinal image. This combination compromises both accurate spatial and spectral information over the selected slit. Hyperspectral image analysis was used as input for the oximetry calculations described in the literature. We used a model eye to evaluate the different techniques in a controlled setup. Defibrinated horse blood was perfused through microtubules placed in front of a white (spectralon) background. Oxygen saturation was controlled by mixing different concentrations of sodium dithianate in the blood.

Results Oxygen saturation was varied in five equidistant steps between 0 and 1. We correlated the outcomes to the metric of Harvey et al. [Biomed Optics 6631, 2007] Linear correlation with other algorithms resulted in r2 values between 0.881 and 0.985, however we observed a large discrepancy of the slope of each correlation line. The algorithms were also evaluated in images recorded in five healthy volunteers. In all techniques, veins could be separated from arteries by their reduces oxygen saturation, although values varied strongly between the different techniques.

Conclusion Our findings confirm the working of a number of noninvasive retinal oximetry algorithms. Different readings can be can be attributed to an offset caused by an uncertainty of pigmentation and scattering parameters in the calibration procedure.
Dynamic retinal vessel analysis – how different parameters create the whole picture
Authors: LANZL I , KOTLIAR K
Published: November 2010

Purpose Dynamic vessel analysis is usually associated with the observation of the reaction of retinal vessels to a defined stimulus. The data which is generated this way may be further analysed with respect to the dynamic unstimulated and stimulated vessel behaviour. Assessment of different parameters may highlight different aspects of the underlying disease.

Methods Vessel diameters of retinal vessel segments were assessed by Dynamic Vessel Analyzer (DVA) in healthy volunteers of different age groups and patients with diabetes, glaucoma and systemic hypertension. Mathematical analysis of unstimulated vessels was used to describe vessel wall characteristics. Methods of signal analysis including Fourier Transformation, spectral filtration, auto‐ and cross correlation were applied to evaluate characteristic oscillations and pulse wave propagation along the vessel.

Results Characteristic different vessel behaviour and vessel wall conformation are obtained by dynamic quantitative evaluations from the unstimulated vessels in physiologic aging and disease.

Conclusion Dynamic vessel analysis includes information which may lead to further understanding of the vascular status and underlying disease pathology. It is also feasible to assess pulse wave velocities in retinal arterioles und thus clinically characterize the elasticity of the upstream vasculature in health and disease.
Are the Meibomian glands “hair follicles without a hair shaft” ?
Authors: KNOP E , KNOP N
Published: November 2010

Purpose The Meibomian glands (MG) are atypically large sebaceous glands in the eyelids with numerous generations of secretory acini along an extensive central duct. They share similarities with the ciliary hairs in development, and hyper‐keratinisation leading to obstructive MG dysfunction (MGD) represents the typical pathology. It was hence investigated which structural similarities they share with cilia.

Methods Conjunctival whole‐mounts including the lid margin from ten normal human body donors were embedded in paraffin. Serial sections were stained by H&E, Masson‐Goldners stain and by immunohistochemistry (IHC) against cytokeratins and associated proteins.

Results The terminal part (excretory duct) of the MG central duct is an ingrowth of epidermis similar to the hair follicles of the cilia. Characterization of individual cytokeratinis by IHC showed that CK14, a marker for undifferentiated cells, was expressed in the basal cell layer of the skin, MG ducts and the secretory acini. The excretory duct epithelium expressed the skin keratin CK10 and the keratinisation marker involucrin but in proximal direction along the central duct full cornification as well as both markers were gradually lost. Filaggrin, however, a marker for incipient stages of keratinisation located in keratohyalin granules continued in the superficial epithelial layer all along the MG ductal system.

Conclusion All parts of the normal human MG ductal system have signs of incipient keratinisation and preserve a commitment to full cornification. This supports the assumption that the MG are basically “hair follicles without a hair shaft” in which the progression to full epithelial cornification is apparently blocked during embryological development but may reoccur under pathological influences. Support DFG KN317/11
The challenge of interpreting the histomorphology of human fetal lenses
Authors: LOEFFLER KU , HERWIG MC , HOLZ FG , MüLLER AM
Published: November 2010

Purpose On histology, the crystalline lens is – especially in fetal and infant eyes ‐ an organ susceptible to numerous artifacts. Nevertheless, evaluation of the lens is often of paramount importance in the classification of fetal syndromes or forensic questions. Thus, the aim of our study is to evaluate various factors that might have an impact on lens histomorphology.

Methods Our collection of eyes by now comprises more than 500 specimens from fetuses with a gestational age between 8 and 38 weeks, including a variety of syndroms. Apart from induced fetocid, death occured due to spontaneous abortion or post‐natally. Specimens were fixed in formalin, and in selected cases one eye was put into Karnovsky's solution for comparison. All systemic findings as well as data related to the termination procedure were recorded. ‐ Some individual cases shall be presented to demonstrate the variability of histopathologic findings.

Results Most of the eyes revealed lens features different from the descriptions available in textbooks. At all ages, there were various morphologic changes particularly of the subcapsular cortex, compatible with cataractous lenses in the adult, while the well‐known phenomenon of an indentation at the posterior pole was seen especially in older fetuses. The difference in fixatives had only a moderate impact on structural alterations.

Conclusion Alterations in fetal lens morphology are extremely frequent and variable. These can be due to delayed fixation, cutting artifacts and other variables and have to be carefully taken into account particularly when interpreting post‐mortem findings. The diagnosis of a fetal cataract should therefore only be made with great caution and not without a careful macroscopic evaluation.
Identification of a new locus in autosomal dominant retinitis pigmentosa and strategy for molecular diagnosis
Authors: MANES G , COUSTES‐CHAZALETTE D , BOCQUET B , DELAERE V , DEVOS A , DHAENENS CM , HéBRARD M , MEUNIER I , HAMEL C
Published: November 2010

Purpose Autosomal dominant retinitis pigmentosa (adRP) affects approximately 1 in 12,000 individuals. To date, 21 adRP genes have been identified accounting theoretically for 44.7% of adRP families; therefore, genetic defects in many patients are yet to be identified. This study was intended to provide information on prevalence of known adRP genes in France and to localize new genes and loci.

Methods Microsatellite markers for the 21 adRP genes were used to genotype large families. Non excluded genes were then sequenced. For some families, we performed a whole‐genome SNP analysis using Affymetrix 250K or 6.0 chips. For small families, the 8 most frequently mutated adRP genes were sequenced (in full for RHO, in hot spots only for PRPF31, RDS, RP1, PRPF8, IMPDH1, NRL and PRPF3).

Results Hitherto 18 adRP families were studied by indirect genotype analysis. Of these, 15 have shown mutations in known genes and 2 are still in progress. For the last family, one new locus was identified by whole‐genome SNP analysis and confirmed by microsatellite genotyping defining a 43‐Mb locus on chromosome 2. The direct sequencing approach was performed on 143 proband DNAs (completely for the first 50 patients and only RHO for the 93 other patients). A causative mutation was found for 20 families (14%), among which 9 out of 11 were novel.

Conclusion The preliminary results, on this limited cohort, showed that the prevalence of known genes is probably underestimated in the literature because the causative mutation was found for 15 families out of 18 (83%). However one new locus has been identified and is under active investigation.
Multifactorial traits in keratoconus: how and why traits show family resemblance
Authors: GAJECKA M , KULINSKA K , KAROLAK J , CZUGALA M , RYDZANICZ M , WAMPOLE J , MOLINARI A , PITARQUE J , BEJJANI B , NOWAK D
Published: November 2010

Purpose Mapping and genome sharing among affected individuals continue to be important for establishing a link between a genomic variant and its phenotypic consequences. Several loci responsible for a familial form of keratoconus (KTCN) have been mapped, however; no mutations in any genes have been identified for any of these loci. Here we present further sequencing results of candidate keratoconus genes localized to 13q32 and 13q34 and accompanying linkage analyses performed in Ecuadorian families.

Methods Genes were screened by standard techniques using 48 genomic DNA samples from individuals from family KTCN‐014 and selected affected and unaffected individuals from other Ecuadorian families. Coding exons and intron‐exon boundaries of the genes were evaluated. Additional bioinformatics analyses were carried out based on the genomewide scan data obtained from 79 patients with keratoconus and 66 healthy family members.

Results Sequencing of COL4A1 and COL4A2 genes at 13q34 have been completed. Several single nucleotide polymorphisms were identified in coding and non‐coding regions. Haplotype analysis in family KTCN‐014 at 13q32 revealed three sequence variants segregating with keratoconus phenotype. Bioinformatics analyses revealed distinct keratoconus loci in particular Ecuadorian families indicating complexity of genetics in familial keratoconus.

Conclusion Our results show high complexity of genetics in familial keratoconus
Mutation in the Bmpr1b gene affects optic nerve development
Authors: GRAW J , WEBER S , PUK O , WAGNER S , KLAFTEN M , THIELE F , FUCHS H , HRABé DE ANGELIS M
Published: November 2010

Purpose Systematic analysis of the ocular defects in a new mouse mutant carrying a Bmpr1b mutation.

Methods The Bmpr1b mutants were analyzed by slit lamp, funduscopy, laser interference biometry, electroretinography, virtual drum, histology and in‐situ hybridization.

Results The new Bmpr1b mutant is characterized by a T‐>G transversion in the splice donor site of exon 10. The mutants show irregular forelimb and hindlimb morphology, brachydactyly, irregular cartilage development and alterations in the reproductive system. The lens is clear, but in homozygous mutants, an enlarged optic disc was observed by funduscopy. The eyes are slightly larger, which is mainly due to an increased aqueous humor. Electroretinography demonstrated a more rapid decline of the b‐wave indicating a less efficient transmission of electric stimuli within the retina. Moreover, homozygous mutant mice show also almost no response to moving stripes as compared to the wild type mice. Histological analysis indicated dramatic changes in the optic nerve head. Analysis of the embryonic development of the eye showed that the expression area of Pax6 expands posterior, and concomitantly, Pax2 expression (which is regular at embryonic day 11.5) is repressed at embryonic days 15.5 and 17.5 at the optic nerve head.

Conclusion The T‐G mutation in the splice donor site of exon 10 of the Bmpr1b gene leads to a recessive hypoplasia of the optic nerve head, which is mainly caused by repression of Pax2 expression in the late phase of embryogenesis.
Novel mutation in the TGFBI gene in a patient with a late‐onset lattice corneal dystrophy
Authors: OLDAK M , SZAFLIK JP , MAKSYM RB , UDZIELA M , FRANASZCZYK M , PIOSKI R , SZAFLIK J
Published: November 2010

Purpose To report the clinical and molecular findings in a patient with late‐onset lattice corneal dystrophy and a novel Leu565Pro mutation in the TGFBI gene.

Methods The diagnosis of lattice corneal dystrophy (LCD) was performed by visualization of characteristic lesions with slit‐lamp examination and by in vivo confocal microscopy. Mutation screening of coding regions of the TGFBI gene was done by PCR amplification and direct sequencing.

Results We found a novel c.1694T>C heterozygous missense mutation in exon 13 of the TGFBI gene, which predicts the substitution of a leucine for a proline at codon 565 (Leu565Pro). Sequencing of all remaining exons of the TGFBI gene did not show any alterations.

Conclusion The mutant codon 565 is located at the C‐terminus in the region corresponding to the fourth fascilin domain of the TGFBI protein. The novel variant adds to a number of previously reported mutations causing lattice corneal dystrophy and located in this region.
Biomechanical analysis of the pressure‐volume relationship in a statically loaded human eye
Authors: STEIN AA , MOISEEVA IN
Published: November 2010

Purpose To develop an approach for estimating the mechanical characteristics of the individual eye in the ophthalmologic procedures based on static load application (tonometry, et al.).

Methods The fibrous coat is mathematically modeled as a soft elastic shell (cornea) connected with an elastic system that mainly consists of the sclera and is characterized by a single elastic constant describing its response to the intraocular pressure. A function representing the intraocular volume as a function of two variables, the intraocular pressure and the load applied, called the volume function is introduced. This function is then specified on the basis of a simple model characterized by two elastic constants in the case of an applanating load.

Results A general method of estimating the integral elastic behavior of the individual eye is developed and specific relationships between elastic constants important in different loading processes are obtained.

Conclusion The method developed makes it possible to reliably estimate the integral elastic behavior of the fibrous coat and, as a result, to obtain more correct data on the intraocular pressure and other mechanical characteristics. Although in different loading processes (for example, in tonometry and inflating the eye by a liquid volume) different integral elastic contacts are involved, the model proposed provides a means for obtaining efficient approximate relationships between these constants.
Neuromyelitis optica and AQP4 antibodies in consecutive optic neuritis patients
Authors: SIUKO M , TIENARI PJ , KIVELÄ T , SAASTAMOINEN KP , MIETTINEN A , SETÄLÄ K
Published: November 2010

Purpose To analyse the frequency of neuromyelitis optica (NMO) among consecutive optic neuritis (ON) patients in Southern Finland and to analyse correlation of Aquaporin‐4 (AQP4) antibody titre with the severity of ON and with the diagnosis of NMO.

Methods All patients with symptoms suggestive of acute ON and treated in the Helsinki Eye Hospital have been screened for AQP4 antibodies from May 2008 onwards. Diagnosis of NMO among the ON patients was evaluated prospectively and retrospectively. AQP4 antibodies were measured using Radioimmunoprecipitation assay (Seelig‐lab). Antibody titres >15 were considered pathological, 10‐15 borderline, and <10 were considered normal. Brain magnetic resonance imaging (MRI) was performed in all patients.

Results We screened 131 patients who had symptoms suggesting ON. Of the 131 patients 24 (18%) were eventually diagnosed with a condition other than ON. Of the remaining 107 patients classified as ON (77% females), 35 (33%) had multiple sclerosis (MS), 25 (23%) had demyelination by MRI, but did not fulfill the criteria for MS, and 47 (44%) had no MRI evidence of demyelination. The median AQP4 anti‐body titer was 7.3 (range 4.8‐53.5). Pathological AQP4 antibody titres were found in three cases, one with NMO, one with MS and one with a clinically isolated syndrome suggestive of MS fulfilling Barkhof’s MRI criteria. Borderline AQP4 antibody titres were found in 8 cases. Only one patient with NMO was found and he had pathological AQP4 antibody titer.

Conclusion In the southern Finnish population, NMO is rare among ON patients. In this cohort the AQP4 antibody test was not specific for NMO.
The effects of stress on nystagmus (INS): acuity vs. time to see
Authors: ERICHSEN JT , WOODHOUSE JM , MARGRAIN TH , ENNIS F , HARRIS CM , JONES PH
Published: November 2010

Purpose People with congenital nystagmus (INS) report that stress has a deleterious impact their vision, yet recent research suggests that stress does not affect visual acuity (VA). This study investigated what underlies the perception that stress causes poorer vision in INS.

Methods VA was measured using a two alternate forced choice (2AFC) staircase method. Subjects were asked to identify whether the gap in a Landolt C of decreasing size was either left or right. Eye movements and skin conductance (a measure of arousal level) were simultaneously recorded. Stress was induced with the threat of a brief shock from a Transcutaneous Electric Nerve Stimulation (TENS) machine at double the subject’s previously determined threshold, although this was never actually done. Subjects carried out the visual task four time: twice under relaxed conditions, and twice under stressed conditions (i.e. shock linked to performance and shock at random intervals).

Results The intensity of eye movements was significantly increased during periods of stress (paired t test, p<0.05), as was skin conductance (p<0.05). Consistent with other studies, VA was not affected (p=0.73), but the time taken for subjects to respond to the stimulus was significantly longer during periods of stress (p<0.05).

Conclusion The results suggest that aspects of “vision” other than VA can better reflect the problems experienced by people with INS when under stress. We confirm that VA is unaffected; subjects do take longer to identify the target. We conclude that clinical or experimental measures of VA alone are insufficient to determine the visual problems faced by people with nystagmus. Additional tests such as measurement of the time taken to identify a target are recommended.
Laser and oxygen
Authors: POURNARAS CJ
Published: November 2010

Purpose To evaluate the changes in the retinal oxygen partial pressure (PO2) following photocoagulation as well as the resulting effect of the laser induced improved oxygenation, on the retinal vessels hemodynamics.

Methods Measurements of the partial pressure of oxygen (PO2) distribution within the retina in various animal species using oxygen sensitive microelectrodes and evaluation of changes on the retinal vessels reactivity, following laser treatment, gave additional insights concerning photocoagulation mechanisms.

Results Preretinal intervascular PO2 , far away from vessels, remain constant in all retinal areas. Intervascular intraretinal PO2 gradually decreases from both the vitreo‐retinal interface and the choroid towards the mid‐retina. Close to the pigment epithelium, it is significantly higher than at the vitreoretinal interface due to the much higher O2 supply provided by choroidal compaires to retinal circulation. Laser photocoagulation reduces the outer retina O2 consumption and allows O2 diffusion into the inner retina from the choroid raising the PO2 in the inner healthy retinal layers and in the preretinal intervascular normal areas. In this way, laser treatment relieves retinal hypoxia in experimental branch vein occlusion (BRVO). In patients with diabetic retinopathy (DR), the retinal PO2 is also higher in areas previously treated with laser. Following photocoagulation, the resulting reversal of hypoxia, the down‐regulation of the VEGF expression, the retinal vasculature constriction and the improvement of the auto‐regulatory response to physiological stimuli, all affect favorably both the retinal neovascularisation and macular edema.

Conclusion Photocoagulation induces an increase of the inner retinal oxygenation resulting to an improvement of the autoregulatory retinal vessels response.
Mesopic visual function as a prognostic indicator of early age‐related maculopathy
Authors: PEREZ CARRASCO MJ , PUELL MC , BARRIO AR , PALOMO‐ALVAREZ C , GOMEZ‐SANZ FJ , CLEMENT‐CORRAL A
Published: November 2010

Purpose Rod photoreceptors, which mediate night vision, are vulnerable early in age‐related maculopathy (ARM) pathogenesis. This study was performed to analyze mesopic visual function of early ARM subjects.

Methods The samples were 40 early ARM eyes of adults (65 ± 7 years), and 34 age‐matched healthy control eyes (67 ± 6 years). The selected criteria in both samples were: Best‐corrected VA of at least 0.9 decimal. Under photopic (80 cd/m2) and mesopic (0.1 to 0.2 cd/m2) luminance conditions and with the best‐optical correction, the logMAR VA was measured using high‐contrast (HC‐96%) and low‐contrast (LC‐10%) logMAR Bailey‐Lovie letter charts, and the mesopic contrast sensitivity (CS) was assessed with Pelli‐Robson Test

Results Photopic high and low‐contrast VA showed no statistically differences between the two groups. Under mesopic conditions, the HC logMAR VA was 0.54 ± 0.13 in ARM group and 0.46 ± 0.10 in Control group. The ARM LC logMAR VA was 0.72 ± 0.11 and the Control LC logMAR VA was 0.99 ± 0.13. Differences in mesopic high and low contrast logMAR VA between the Control and ARM group were statistically significant; the Control group showing best logMAR VA at high and low contrast (p< 0.00). The mesopic ARM logCS was 0.99 ± 0.21 and the mesopic Control logCS was 1.19 ± 0.14. In ARM group, the mean mesopic log CS was 0.2 ± 0.08 log units lower (p< 0.00) than in the Control group.

Conclusion The results indicated that assessment of the mesopic high and low contrast logMAR VA and log CS might potentially predict the mesopic visual function and the first night‐vision problems of the early ARM disease process
Compartment syndrome in glaucoma damage, a new hypothesis?
Authors: ORGUL S
Published: November 2010

Purpose To evaluate the potential similarities in pathophysiology between non‐arteritic anterior ischemic optic neuropathy (AION) and primary open‐angle glaucoma (POAG).

Methods The currently accepted views of the pathophysiology of AION and general understanding of the clinical picture of this ischemic condition were reviewed. Based on the hypothesis of the group in Wisconsin, who postulated a compartment syndrome of the anterior optic nerve within the tight anatomical structures of the lamina cribrosa, parallels were drawn for glaucomatous optic neuropathy, and a new hypothesis for the pathogenesis of the latter condition was suggested.

Results The tight structures around, but also within the “disk at risk” observed in a majority of patients with AION are well compatible with the hypothesis of a compartment syndrome. Similar conditions may result from the restructuring process within the lamina cribrosa in POAG and lead to locally limited, but repeated "AION‐like" processes, explaining why some patients progress despite reduced intraocular pressure.

Conclusion The pathophysiology of POAG, especially in advanced cases, and AION seem to present similarities, which need to be better understood.
Pulsatile haemodynamics: potential for end‐organ damage?
Authors: HUDSON C
Published: November 2010

Purpose Increases in velocity pulse wave amplitude, or max:min velocity ratio, represent early haemodynamic disturbances associated with diabetic retinopathy (DR) and age‐related macular degeneration. This change reflects an increase in vessel wall rigidity that is generally accepted to occur in the central vasculature but the peripheral vasculature is also implicated in this process. This presentation will highlight the implications of these changes in terms of end‐organ damage in DR.

Methods The sample comprised 4 groups: Group 1: 50 non‐diabetic control subjects. Group 2: 56 diabetic patients without clinically visible DR. Group 3: 54 diabetic patients with micro‐aneurysms and / or hard exudates within 2 disc diameters of the fovea in the absence of clinically manifest diabetic macular edema (DME). Group 4: 40 patients with clinically manifest DME. The diabetic patients were predominantly type 2. Retinal hemodynamics were assessed in the superior temporal retinal arteriole using the Canon Laser Blood Flowmeter. Intraocular pressure, blood pressure and relevant systemic markers of diabetes control and complications were also assessed.

Results The velocity pulse wave amplitude was elevated with increasing risk of DME (p<0.0001). No significant differences were found between the groups with respect to diameter, velocity or flow. Pulse wave amplitude was correlated to age, duration of diabetes, blood pressure, pulse rate, IOP and serum potassium levels.

Conclusion The increase in velocity pulse wave amplitude will induce excessive pressure pulsatility in the retinal arterioles and capillaries, changes in vascular function (e.g. loss of vascular regulation) and changes in vessel structure.

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