Retinal Layers (retinal + layer)

Distribution by Scientific Domains


Selected Abstracts


Comparison of wild-type and class I integrase mutant-FIV vectors in retina demonstrates sustained expression of integrated transgenes in retinal pigment epithelium

THE JOURNAL OF GENE MEDICINE, Issue 12 2003
Nils Loewen
Abstract Background In neonatal and adult rodent retina, substantial lentiviral vector expression has been detected primarily in retinal pigment epithelium (RPE), except in very young animals (2,5 days post-natal). In non-retinal tissues, studies of lentiviral vectors have utilized various controls. Among the most stringent are class I integrase mutants, which selectively block the integration reaction while leaving all other gag/pol -encoded functions intact. For HIV-1 vectors injected into brain, these have been used to simultaneously control for pseudotransduction and verify that long-term expression requires integration. Such experiments compare particles that differ only in a single amino acid within a single enzyme that forms a very small molar fraction of the virion. Class I integrase mutants have not been described for feline immunodeficiency virus (FIV) integrase, or tested in the eye for any lentiviral vector. Methods We compared subretinally and intravitreally injected FIV vectors and followed animals for up to 7 months, a duration that exceeds prior studies. We also compared the wild-type (WT) vector with one incorporating a single class I amino acid mutation in FIV integrase (D66V). A mock vector (packaging construct absent) was an alternative control. All vectors were vesicular stomatitis virus glycoprotein G (VSV-G)-pseudotyped and were injected on day 7 of life. One group of animals received either subretinal or intravitreal injections of WT vector in the right eyes. Control left eyes were injected with mock vector. These animals were sacrificed at 2 or 7 days post-injection. A second group received subretinal injections of either WT vector or equivalent D66V vector (reverse transcriptase-normalized to WT), and were analyzed after 2, 3 and 7 months. All eyes were scored for marker gene (,-galactosidase) expression by an observer blinded to vector assignments. Results Subretinal FIV vector injections were much more effective than intravitreal injections. The RPE was the principal retinal layer transduced by the WT vector, and at least 50% of the area of the retina expressed the marker gene at 3 and 7 months. Occasional cells in inner retinal layers also expressed ,-galactosidase at these time points. The sustained retinal expression produced by subretinally injected vector was blocked by the D66V mutation. Conclusions These results show that class I integrase mutant FIV vectors are useful control vectors, and that VSV-G-pseudotyped FIV vectors produce extensive retinal expression for at least 215 days, the longest duration yet reported for lentiviral vectors in retina. Transgene expression is mostly restricted to RPE after post-natal day 7 in rats, suggesting that FIV vectors could be used to target RPE for gene therapy. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Telangiectasis as a cause of intra-schitic haemorrhage in optic disc pit maculopathy

ACTA OPHTHALMOLOGICA, Issue 1 2004
Shauna M. Quinn
Abstract. Purpose:, To present a patient with the novel finding of vascular telangiectasis as a cause of intra-schitic haemorrhage, occurring in optic disc pit-associated maculopathy. Methods:, A clinical history was detailed. Clinical examination included visual acuity assessment and slit-lamp microscopy. Fluorescein angiography was performed. Results:, A temporal optic disc pit, macular retinoschisis and a circumscribed detachment of the outer retinal layer and inner leaf holes were noted. A retinal haemorrhage extending into the schitic cavity was present, along with an associated vitreous haemorrhage. Fluorescein angiography showed telangiectatic vessels in association with the haemorrhage. Conclusion:, This is the first reported case of vascular telangiectasis as a cause of intra-schitic haemorrhage occurring in optic disc pit-associated maculopathy. [source]


The embryonic expression patterns and the knockdown phenotypes of zebrafish ADP-ribosylation factor-like 6 interacting protein gene

DEVELOPMENTAL DYNAMICS, Issue 1 2009
Hsing-Yen Huang
Abstract ADP-ribosylation factor-like 6 (Arl6) mutation is linked to human disease and Arl6 interacts with Arl6 interacting protein (Arl6ip). However, the expression pattern and function of Arl6ip during embryogenesis are unknown. To confirm whether abnormal Arl6ip function might result in embryonic defects in zebrafish, we examined the expression patterns of arl6ip during embryogenesis, and they were maternally expressed and exhibited in the brain, optic primordia, hypochord, spinal cord, myotome, heart, fin-bud, kidney, trunk, and retina. Knockdown of Arl6ip revealed the following phenotypic defects: microphthalmia, disorganized pigment pattern, flat head, defective tectum, deficient pectoral fins, abnormal pneumatic duct, pericardial edema, and deformed trunk. Particularly, histological dissection of the retinae of arl6ip -morphants revealed that neuronal differentiation is severely delayed, resulting in no formation of retinal layers. We further confirmed that opsins of arl6ip -morphants were not transcribed. Based on this evidence, Arl6ip may play important roles in zebrafish ocular, heart, and fin-bud development. Developmental Dynamics 238:232,240, 2009. © 2008 Wiley-Liss, Inc. [source]


Expression patterns of focal adhesion associated proteins in the developing retina

DEVELOPMENTAL DYNAMICS, Issue 4 2002
Ming Li
Abstract Adhesive interactions between integrin receptors and the extracellular matrix (ECM) are intimately involved in regulating development of a variety of tissues within the organism. In the present study, we have investigated the relationships between ,1 integrin receptors and focal adhesion associated proteins during eye development. We used specific antibodies to examine the distribution of ,1 integrin ECM receptors and the cytoplasmic focal adhesion associated proteins, talin, vinculin, and paxillin in the developing Xenopus retina. Immunoblot analysis confirmed antibody specificity and indicated that ,1 integrins, talin, vinculin, and paxillin were expressed in developing retina and in the retinal-derived Xenopus XR1 glial cell line. Triple-labeling immunocytochemistry revealed that talin, vinculin, paxillin, and phosphotyrosine proteins colocalized with ,1 integrins at focal adhesions located at the termini of F-actin filaments in XR1 cells. In the retina, these focal adhesion proteins exhibited developmentally regulated expression patterns during eye morphogenesis. In the embryonic retina, immunoreactivities for focal adhesion proteins were expressed in neuroepithelial cells, and immunoreactivity was especially strong at the interface between the optic vesicle and overlying ectoderm. At later stages, these proteins were expressed throughout all retinal layers with higher levels of expression observed in the plexiform layers, optic fiber layer, and in the region of the inner and outer limiting membrane. Strong immunoreactivities for ,1 integrin, paxillin, and phosphotyrosine were expressed in the radially oriented Müller glial cells at later stages of development. These results suggest that focal adhesion-associated proteins are involved in integrin-mediated adhesion and signaling and are likely to be essential in regulating retinal morphogenesis. © 2002 Wiley-Liss, Inc. [source]


Comparison of wild-type and class I integrase mutant-FIV vectors in retina demonstrates sustained expression of integrated transgenes in retinal pigment epithelium

THE JOURNAL OF GENE MEDICINE, Issue 12 2003
Nils Loewen
Abstract Background In neonatal and adult rodent retina, substantial lentiviral vector expression has been detected primarily in retinal pigment epithelium (RPE), except in very young animals (2,5 days post-natal). In non-retinal tissues, studies of lentiviral vectors have utilized various controls. Among the most stringent are class I integrase mutants, which selectively block the integration reaction while leaving all other gag/pol -encoded functions intact. For HIV-1 vectors injected into brain, these have been used to simultaneously control for pseudotransduction and verify that long-term expression requires integration. Such experiments compare particles that differ only in a single amino acid within a single enzyme that forms a very small molar fraction of the virion. Class I integrase mutants have not been described for feline immunodeficiency virus (FIV) integrase, or tested in the eye for any lentiviral vector. Methods We compared subretinally and intravitreally injected FIV vectors and followed animals for up to 7 months, a duration that exceeds prior studies. We also compared the wild-type (WT) vector with one incorporating a single class I amino acid mutation in FIV integrase (D66V). A mock vector (packaging construct absent) was an alternative control. All vectors were vesicular stomatitis virus glycoprotein G (VSV-G)-pseudotyped and were injected on day 7 of life. One group of animals received either subretinal or intravitreal injections of WT vector in the right eyes. Control left eyes were injected with mock vector. These animals were sacrificed at 2 or 7 days post-injection. A second group received subretinal injections of either WT vector or equivalent D66V vector (reverse transcriptase-normalized to WT), and were analyzed after 2, 3 and 7 months. All eyes were scored for marker gene (,-galactosidase) expression by an observer blinded to vector assignments. Results Subretinal FIV vector injections were much more effective than intravitreal injections. The RPE was the principal retinal layer transduced by the WT vector, and at least 50% of the area of the retina expressed the marker gene at 3 and 7 months. Occasional cells in inner retinal layers also expressed ,-galactosidase at these time points. The sustained retinal expression produced by subretinally injected vector was blocked by the D66V mutation. Conclusions These results show that class I integrase mutant FIV vectors are useful control vectors, and that VSV-G-pseudotyped FIV vectors produce extensive retinal expression for at least 215 days, the longest duration yet reported for lentiviral vectors in retina. Transgene expression is mostly restricted to RPE after post-natal day 7 in rats, suggesting that FIV vectors could be used to target RPE for gene therapy. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Retinal and Optic Nerve Diseases

ARTIFICIAL ORGANS, Issue 11 2003
Eyal Margalit
Abstract:, A variety of disease processes can affect the retina and/or the optic nerve, including vascular or ischemic disease, inflammatory or infectious disease, and degenerative disease. These disease processes may selectively damage certain parts of the retina or optic nerve, and the specific areas that are damaged may have implications for the design of potential therapeutic visual prosthetic devices. Outer retinal diseases include age-related macular degeneration, pathologic myopia, and retinitis pigmentosa. Although the retinal photoreceptors may be lost, the inner retina is relatively well-preserved in these diseases and may be a target for retinal prosthetic devices. Inner retinal diseases include retinal vascular diseases such as diabetic retinopathy, retinal venous occlusive disease, and retinopathy of prematurity. Other retinal diseases such as ocular infections (retinitis, endophthalmitis) may affect all retinal layers. Because the inner retinal cells, including the retinal ganglion cells, may be destroyed in these diseases (inner retinal or whole retinal), prosthetic devices that stimulate the inner retina may not be effective. Common optic nerve diseases include glaucoma, optic neuritis, and ischemic optic neuropathy. Because the ganglion cell nerve fibers themselves are damaged, visual prosthetics for these diseases will need to target more distal portions of the visual pathway, such as the visual cortex. Clearly, a sound understanding of retinal and optic nerve disease pathophysiology is critical for designing and choosing the optimal visual prosthetic device. [source]


4212: Protective role of xanthophylls

ACTA OPHTHALMOLOGICA, Issue 2010
N ACAR
Xanthophylls, also known as carotenoids are a group of natural fat-soluble pigments that are especially abundant in green and yellow-orange fruits and vegetables. Based on epidemiologic data, it is now evident that carotenoids provide health benefits and particularly in eye diseases. Molecular characterization of retinal carotenoids has shown that there were actually two xanthophylls that are concentrated in macular region, namely lutein and zeaxanthin. Thanks to a strategic position within inner retinal layers, lutein and zeaxanthin are suspected to act as antioxidants in the retina in order to limit oxidative stress that results from metabolism of light. In addition, they are also supposed to absorb blue light that enters the eye prior to its reaching the delicate functional structures including the photoreceptors and the retinal pigment epithelial cells. The aim of this paper is to summarize the knowledge about the biological mechanisms of the protective role of macular xanthophylls. [source]


2452: Patients in the DARC: drops revealing retinal ganglion cells in vivo

ACTA OPHTHALMOLOGICA, Issue 2010
MF CORDEIRO
Purpose To provide a review of current & future DARC imaging technologies and their application to neuroprotection Methods Currently, lowering IOP remains the only clinical therapy available in the treatment of glaucoma, despite the evidence that vision loss can continue in the presence of "significant" IOP reduction. Neuroprotection has been increasingly recognized as an important alternative treatment approach, but its emergence has also highlighted the need for both better defined end-points in clinical glaucoma research, as well as earlier and better detection and measures of progression. This could have been a factor in the recent memantine trial. A recent FDA/NEI meeting on end-points in glaucoma emphasized the need for new measurements. As the RGC is the primary injured neuron in this disease, it would seem logical that any modality that could directly measure RGC dysfunction and disease would be ideal. Perhaps the greatest changes that we have encountered recently are in the field of imaging technologies, which have only relatively recently been applied to the eye. Results Advances in this area have allowed unprecedented in vivo access to the retinal layers, using many different properties of light to differentiate cellular structures. DARC is a technology shortly to enter clinical trials which allows the visualization of "sick" RGCs. Conclusion Over the next few years, developments in therapy & diagnostic using DARC should offer great potential in glaucoma and other neurodegenerative conditions. Commercial interest [source]


2412: Laser and oxygen

ACTA OPHTHALMOLOGICA, Issue 2010
CJ POURNARAS
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. [source]


4123: The use of the mfERG in the clinic

ACTA OPHTHALMOLOGICA, Issue 2010
A PALMOWSKI
Purpose This presentation is to give a brief overview on the application of the multifocal electroretinogram (mf-ERG) in the clinic. Methods The use of m-sequences as a stimulus sequence allows a high resolution topographic mapping of sensory function. The mf-ERG can be readily applied to detect outer retinal dysfunction in the area of the macula. Different retinal layers contribute to the waveform of the mf-ERG. This results in typical changes of the waveform, when these different layers are dysfunct. Results MF-ERG examples are shown, that demonstrate how this knowledge can be useful in the clinical evaluation of patients. Conclusion The mf-ERG is a helpful tool in the clinical evalutation of patients. [source]


Unilateral choroidal excavation in the macula detected by spectral-domain optical coherence tomography

ACTA OPHTHALMOLOGICA, Issue 3 2010
Yuka Wakabayashi
Abstract. Purpose:, To report clinical findings of three patients with unilateral peculiar choroidal excavation in the macula detected by spectral-domain (SD) optical coherence tomography (OCT). Methods:, Three cases with unilateral choroidal excavation in the macula detected by SD OCT. Fluorescein angiography (FA), indocyanine green angiography (IA), ultrasonography, visual field tests and multifocal electroretinography (mfERG) were performed. Results:, Although all three patients complained of metamorphopsia, visual acuity and central visual field were normal in the affected eyes. SD OCT demonstrated choroidal excavation in the macula despite a normal foveal contour along the inner retinal surface. The excavation involved the outer retinal layers up to the external limiting membrane in cases 1 and 2, while only the retinal pigment epithelium was involved in case 3. The excavation corresponded to foveal pigment mottling in cases 1 and 2 and to a parafoveal yellowish fusiform lesion in case 3. The lesions appeared hypoautofluorescent and unremarkable in FA except for circumferential hyperfluorescence in case 3 and hypofluorescent in IA. B-scan ultrasonography was unremarkable. MfERG in cases 1 and 2 was normal. Conclusions:, SD OCT demonstrated two types of choroidal excavation in the macula. More case accumulation and a longer follow-up will elucidate the pathogenesis and prognosis of the lesions. [source]


Retinal photocoagulation and oxygenation

ACTA OPHTHALMOLOGICA, Issue 2009
CJ POURNARAS
Purpose The clinical role of photocoagulation for the treatment of hypoxia related complications of retinal ischemic microangiopathies is well established. Methods Measurements of the partial pressure of oxygen (PO2) distribution within the the retina in various animal species using oxygen sensitive microelectrodes and evaluation of the retinal vessels reactivity by laser doppler velocimetry gave additional insights concerning photocoagulation mechanisms. Results The PO2 within the vitreo-retinal interface is heterogeneous. Preretinal and trans-retinal PO2 profiles indicate that the preretinal 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 higher in areas previously treated with laser. Following photocoagulation, the resulting reversal of hypoxia, the retinal vasculature constriction and the improvement of the regulatory response to hyperoxia all affect favorably both the retinal neovascularisation and macular edema. Conclusion Photocoagulation induces an increase of the inner retinal oxygenation reversing the retinal hypoxia and improving the regulatory response of the retinal vessels [source]


Chorioretinal anastomosis in adaptive optic and high definition spectral domain optical coherence tomography

ACTA OPHTHALMOLOGICA, Issue 2009
C MAILLON
Purpose To assess morphologic variations in the outer and inner retinal layers in eyes with chorioretinal anatomosis using high definition Spectral Domain Optical Coherence Tomography (Spectralis HRA OCT, Heidelberg Engineering, Heidelberg, Germany) and to compare these scans with images acquired by Adaptive Optics (AO). Methods This was a prospective observational case series including 50 patients. SD-OCT scans were obtained with combined confocal scanning laser ophthalmoscope (cSLO) and SD-OCT for simultaneous tomographic and topographic in vivo imaging. Patients underwent fluorescein and ICG- angiography and Adaptive Optics assessment with Imagine EyesŌ System. The neurosensory retina and the photoreceptor layer were analyzed using both HR-OCT and AO imaging. Results Combining of the adaptive optics with SD-OCT may give us further information of the early stage development of chorioretinal anastomosis. [source]


Segmentation of FD-OCT images shows selective loss of inner retinal layers in patients with DM and no or early DR

ACTA OPHTHALMOLOGICA, Issue 2009
FD VERBRAAK
Purpose Determine whether diabetes differentially affects specific retinal layers by comparing the thickness of six retinal layers in diabetic patients with no or minimal diabetic retinopathy (DR) to age- and gender-matched normal controls. Methods Forty-four patients with type 1 diabetes and no or minimal DR underwent full ophthalmic examination, stereoscopic fundus photographs and spectral domain optical coherence tomography (OCT). Following automated segmentation of intraretinal layers of the OCT images, mean thickness was calculated for 6 individual layers of the retina in the fovea, the pericentral area and the peripheral area of the central macula and compared to an age- and gender-matched control group. Results In type 1 diabetic patients with minimal DR, the retinal nerve fiber layer (p=0.00) and the ganglion cell/inner plexiform layer (p=0.02) were significantly thinner compared to age- and gender-matched controls. No other layers showed a significant difference. Conclusion Thinning of the total retina in diabetic patients with minimal DR relative to normal controls is due to a selective thinning of inner retinal layers and supports the concept that early DR includes a neuro-degenerative component. [source]


Ocular coherence tomography in acute posterior multifocal placoid pigment epitheliopathy

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 8 2006
Lyndell L Lim FRANZCO
Abstract The authors report a case of typical acute posterior multifocal placoid pigment epitheliopathy in which an ocular coherence tomographic scan was performed through an acute lesion and then repeated through the same lesion 12 months later. The initial ocular coherence tomographic scan showed marked anterior displacement of both neuroretina and outer reflective band. A subsequent ocular coherence tomographic scan revealed resolution of the prior displacement, increased reflectance of the outer reflective band and mild disruption of the outer retinal layers. These findings are consistent with a primary choroiditis. [source]