Home About us Contact
|
Home About us Contact | ||
|
|
||
Limiting Membrane (limiting + membrane)
Kinds of Limiting Membrane Selected AbstractsExpression patterns of focal adhesion associated proteins in the developing retinaDEVELOPMENTAL DYNAMICS, Issue 4 2002Ming 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] Identification of developmentally regulated expression of MuSK in astrocytes of the rodent retinaJOURNAL OF NEUROCHEMISTRY, Issue 2 2006Tatiana Cheusova Abstract One of the master regulators of postsynaptic neuromuscular synaptogenesis is the muscle-specific receptor tyrosine kinase (MuSK). In mammals prominent MuSK expression is believed to be restricted to skeletal muscle. Upon activation by nerve-derived agrin MuSK-dependent signalling participates in both the induction of genes encoding postsynaptic components and aggregation of nicotinic acetylcholine receptors (AChR) in the subsynaptic muscle membrane. Strikingly, expression of certain isoforms of nerve-derived agrin can also be detected in the CNS. In this study, we examined the expression of MuSK in the brain and eye of rodents. In the retina MuSK was expressed in astrocytes between postnatal days 7 and 14, i.e. at the time when the eyes open. We found that agrin was localized adjacent to MuSK-expressing astrocytes which in turn were detected close to the inner limiting membrane of the rodent retina. In summary, the presence of MuSK on retinal astrocytes suggests a novel role of MuSK signalling pathways in the CNS. [source] Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behaviorTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2009Marcus Robert Jones Abstract An important issue to understand is how visual information can influence the motor system and affect behavior. Using the lamprey (Petromyzon marinus) as an experimental model we examined the morphological subtypes of retinal ganglion cells and their projection pattern to the tectum, which controls eye, head, and body movements, and to the pretectum, which mediates both visual escape responses and the dorsal light response. We identified six distinct morphological types of retinal ganglion cell. Four of these distribute their dendrites in the inner plexiform layer (image forming layer) and project in a retinotopic manner to all areas of the tectum. The posterior part of the retina has the highest density of ganglion cells and projects to the rostral part of the tectum, in which the visual field in front of the lamprey will be represented. From this area both orienting and evasive behaviors can be elicited. In contrast, pretectum receives input from two ganglion cells types that send their dendrites only to the outer plexiform layer or the outer limiting membrane and therefore may directly contact photoreceptors, and transmit information without additional delay to pretectum, which may be particularly important for visual escape responses. One of these two types, the bipolar ganglion cell, is only found in a small patch of retina just ventral of the optic nerve. Due to its distribution, morphology, and projections we suggest that this cell may control the dorsal light response. J. Comp. Neurol. 517:257,275, 2009. © 2009 Wiley-Liss, Inc. [source] Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behaviorTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2009Marcus Robert Jones Abstract An important issue to understand is how visual information can influence the motor system and affect behavior. Using the lamprey (Petromyzon marinus) as an experimental model we examined the morphological subtypes of retinal ganglion cells and their projection pattern to the tectum, which controls eye, head, and body movements, and to the pretectum, which mediates both visual escape responses and the dorsal light response. We identified six distinct morphological types of retinal ganglion cell. Four of these distribute their dendrites in the inner plexiform layer (image forming layer) and project in a retinotopic manner to all areas of the tectum. The posterior part of the retina has the highest density of ganglion cells and projects to the rostral part of the tectum, in which the visual field in front of the lamprey will be represented. From this area both orienting and evasive behaviors can be elicited. In contrast, pretectum receives input from two ganglion cells types that send their dendrites only to the outer plexiform layer or the outer limiting membrane and therefore may directly contact photoreceptors, and transmit information without additional delay to pretectum, which may be particularly important for visual escape responses. One of these two types, the bipolar ganglion cell, is only found in a small patch of retina just ventral of the optic nerve. Due to its distribution, morphology, and projections we suggest that this cell may control the dorsal light response. J. Comp. Neurol. 517:257,275, 2009. © 2009 Wiley-Liss, Inc. [source] Selective projection patterns from subtypes of retinal ganglion cells to tectum and pretectum: Distribution and relation to behaviorTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 3 2009Marcus Robert Jones Abstract An important issue to understand is how visual information can influence the motor system and affect behavior. Using the lamprey (Petromyzon marinus) as an experimental model we examined the morphological subtypes of retinal ganglion cells and their projection pattern to the tectum, which controls eye, head, and body movements, and to the pretectum, which mediates both visual escape responses and the dorsal light response. We identified six distinct morphological types of retinal ganglion cell. Four of these distribute their dendrites in the inner plexiform layer (image forming layer) and project in a retinotopic manner to all areas of the tectum. The posterior part of the retina has the highest density of ganglion cells and projects to the rostral part of the tectum, in which the visual field in front of the lamprey will be represented. From this area both orienting and evasive behaviors can be elicited. In contrast, pretectum receives input from two ganglion cells types that send their dendrites only to the outer plexiform layer or the outer limiting membrane and therefore may directly contact photoreceptors, and transmit information without additional delay to pretectum, which may be particularly important for visual escape responses. One of these two types, the bipolar ganglion cell, is only found in a small patch of retina just ventral of the optic nerve. Due to its distribution, morphology, and projections we suggest that this cell may control the dorsal light response. J. Comp. Neurol. 517:257,275, 2009. © 2009 Wiley-Liss, Inc. [source] Effect of Rds abundance on cone outer segment morphogenesis, photoreceptor gene expression, and outer limiting membrane integrityTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2007Rafal Farjo Abstract We examined the molecular, structural, and functional consequences on cone photoreceptors of the neural retinal leucine zipper knockout (Nrl,/,) mice when only one allele of retinal degeneration slow (Rds) is present (Rds+/,/Nrl,/,). Quantitative RT-PCR and immunoblot analysis were used to assess the expression levels of several phototransduction genes; electroretinography was used to assess quantitatively the retinal responsiveness to light; and immunohistochemistry and ultrastructural analysis were used to examine retinal protein distribution and morphology, respectively. In Rds/Nrl double-null mice, S-cones form dysmorphic outer segments that lack lamellae and fail to associate properly with the cone matrix sheath and the outer limiting membrane. In Rds+/,/Nrl,/, mice, cones form oversized and disorganized outer segment lamellae; although outer limiting membrane associations are maintained, normal interactions with cone matrix sheaths are not, and photoreceptor rosette formation is observed. These retinas produce significantly higher photopic a-wave and b-wave amplitudes than do those of Rds,/,/Nrl,/, mice, and the levels of several cone phototransduction genes are significantly increased coincidently with the presence of Rds and partial lamellae formation. Thus, as in rod photoreceptors, expression of only one Rds allele is unable to support normal outer segment morphogenesis in cones. However, cone lamellae assembly, albeit disorganized, concomitantly permits outer limiting membrane association, and this appears to be linked to photoreceptor rosette formation in the rodless (cone-only) Nrl,/, retina. In addition, photoreceptor gene expression alterations occur in parallel with changes in Rds levels. J. Comp. Neurol. 504:619,630, 2007. © 2007 Wiley-Liss, Inc. [source] Brachiola algerae Spore Membrane Systems, their Activity During Extrusion, and a New Structural Entity, the Multilayered Interlaced Network, Associated with the Polar Tube and the SporoplasmTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2002ANN CALI ABSTRACT. The microsporidial genus, Brachiola, contains three species: the type species Brachiola vesicularum (identified from an AIDS patient) and two species transferred from the genus Nosema, becoming Brachiola connori and Brachiola algerae. A developmental feature of the genus Brachiola is the "thickened" plasmalemma from sporoplasm through sporoblast stage. The sporoplasm has been reported to have a thick plasmalemma at 1-h postextrusion. The purpose of this investigation was to observe B. algerae spores before, during and after germination to determine if the plasmalemma is thick at the point of extrusion and if not, when and how it forms. New understandings regarding the polar filament position inside the spore, places it outside the sporoplasm proper with the sporoplasm limiting membrane imaginations surrounding it. These invaginations, present a possible location for aquaporins. The multilayered interlaced network (MIN), a new organelle (possibly of Golgi origin from the sporoblast), was observed inside the spore and sporoplasm; it formed an attachment to the end of the extruded polar tube and contributed to the thickening of the sporoplasm plasmalemma. A thin "unit limiting membrane", present on the sporoplasm at the time of extrusion, is connected to the MIN by many cross-connections forming the "thick blistered" surface by 30 min-postextrusion. [source] Retinal sensitivity and fixation changes 1 year after triamcinolone acetonide assisted internal limiting membrane peeling for macular hole surgery , a MP-1 microperimetric studyACTA OPHTHALMOLOGICA, Issue 6 2010Hakan Ozdemir Acta Ophthalmol. 2010: 88: e222,e227 Abstract. Purpose:, To evaluate microperimetric changes 1 year after macular hole surgery with triamcinolone acetonide assisted internal limiting membrane (ILM) peeling. Methods:, Twenty-two eyes of 22 patients with stage 3 and 4 idiopathic macular holes of <6 months' duration underwent vitrectomy with triamcinolone acetonide assisted ILM peeling. Best corrected visual acuity (BCVA) (logarithm of the minimum angle of resolution), and central retinal sensitivity were documented before and 1, 3, 6, and 12 months after surgery. Macular sensitivity (mean sensitivity in decibels -dB), and stability and location of fixation (preferred retinal locus) were determined using MP-1 microperimetry (Nidek). The MP-1 microperimetry sensitivity map was overlaid onto infrared images recorded on a Heidelberg scanning laser ophthalmoscope using dedicated MP-1 software to evaluate the fixation location before surgery. Anatomical success was evaluated with optical coherence tomography (OCT). Optical coherence tomography scans were recorded on an OCT 3000 scanner. Results:, Anatomical success was achieved in all 22 eyes. All patients completed 1 year follow-up. No recurrence of macular hole was seen in any patients in the follow-up period. The mean BCVA improved from 0.75 ± 0.2 before surgery to 0.31 ± 0.1 logMAR at the last visit (p < 0.001). Mean sensitivity improved from 3.7 ± 0.6 to 5.3 ± 1.0 dB at the last visit (p < 0.001). Before surgery, the preferred retinal locus was located on the margin of the hole in all, in 18 eyes on its upper part and in four eyes to the side or on its lower part. Preoperatively, 12 eyes were stable and 10 were relatively unstable, but 12 month after surgery, fixation stability had improved, and 20 eyes were stable and two were relatively unstable. Conclusions:, MP-1 microperimetry sensitivity map overlaid onto an infrared image using dedicated MP-1 software can be used successfully to evaluate fixation location in patients with a macular hole before surgery. With microperimetry findings, we can also measure functional macular changes more precisely than using BCVA alone after macular hole surgery. Our results also showed that retinal sensitivity and fixation properties were improved after vitrectomy with triamcinolone acetonide assisted ILM peeling in patients with idiopathic macular hole. [source] Anatomical and functional outcome in brilliant blue G assisted chromovitrectomyACTA OPHTHALMOLOGICA, Issue 5 2010Paul B. Henrich Abstract. Purpose:, To evaluate the potential of brilliant blue G (BBG) for intraoperative staining of the inner limiting membrane (ILM) with respect to staining properties and surgical outcome. Methods:, In a retrospective, non-comparative clinical case series, we analysed 17 consecutive chromovitrectomy interventions for surgery of macular holes, ERMs, vitreoretinal traction syndromes and cystoid macular oedema. Following complete posterior vitreous detachment, BBG was injected into the vitreous cavity at a concentration of 0.25 mg/ml, followed by immediate washout. Main outcome measures were staining properties, visual acuity, central visual field testing and optical coherence tomography (OCT) measurements over a mean follow-up period of 3 months. Results:, ILM staining was somewhat less intensive for BBG than for average indocyanine green (ICG) chromovitrectomy. However, the ILM was removed successfully without additional ICG in 15/17 patients. Postoperative visual acuity was improved in 16/17 patients and remained unchanged in one patient. Central retinal OCT thickness showed a postoperative reduction, with values ranging from +7 to ,295 ,m (median ,89 ,m). Neither visual field defects nor any other adverse events were recorded. Conclusion:, BBG permits sufficient staining for safe ILM removal. In this short-term study, good anatomical and functional results were achieved and no adverse events were observed. [source] Correlation of fundus autofluorescence with photoreceptor morphology and functional changes in eyes with retinitis pigmentosaACTA OPHTHALMOLOGICA, Issue 5 2010Taku Wakabayashi Abstract. Purpose:, To assess and correlate fundus autofluorescence (FAF) characteristics with photoreceptor morphology and functional features in eyes with retinitis pigmentosa (RP). Methods:, Thirty-four eyes of 17 patients with RP were examined. We compared FAF images obtained by confocal scanning laser ophthalmoscopy with Spectral-domain optical coherence tomography (SD-OCT) and retinal function assessed by microperimetry. Results:, Normal FAF surrounded by a ring of increased FAF at the macular area was detected in 32 (94%) eyes. The diameter of the normal FAF was correlated significantly with the preserved area of the photoreceptor inner segment and outer segment (IS/OS) junction on SD-OCT (R = 0.939, p < 0.001). The area outside the ring was associated with loss of IS/OS junction and external limiting membrane (ELM). The ring of increased FAF demarcated the border between the central retina with preservation of the IS/OS junction and ELM, and the adjacent eccentric retina with loss of these bands. In two eyes of one patient, there was no preservation of normal FAF at the macula and the photoreceptor IS/OS junction was not detected on SD-OCT. The mean retinal sensitivity derived from microperimetry was correlated significantly with the area of normal FAF (R = 0.929, p = 0.007) and the preserved area of the IS/OS junction (R = 0.851, p = 0.032). Ten eyes had progressive reduction in size of the normal FAF inside the ring accompanied by decreased area of preserved IS/OS during 3.1 years. Conclusion:, FAF appears to reflect the integrity of the photoreceptor layer. It may serve as a secondary outcome measure for novel therapeutic strategies for RP. [source] Clinical and histological findings after intravitreal injection of bevacizumab (Avastin®) in a porcine model of choroidal neovascularizationACTA OPHTHALMOLOGICA, Issue 3 2010Nathan Lassota Abstract. Purpose:, To examine the effect of intravitreally injected bevacizumab (Avastin®) on the histological and angiographic morphology of choroidal neovascularization (CNV) in a masked and placebo-controlled animal study. Methods:, Choroidal neovascularization was induced surgically in 11 porcine eyes by perforating Bruch's membrane with a retinal perforator. After closure of the ports used for the vitrectomy, which was performed to facilitate the Bruch's membrane rupture, 0.05 ml of either bevacizumab or Ringer-Lactat (placebo) was injected into the vitreous cavity. Eyes were enucleated after 14 days. Fundus photographs and fluorescein angiograms (FAs) were obtained immediately prior to enucleation. Sections of formalin- and paraffin-embedded eyes were examined by light microscopy and by immunohistochemical staining. Results:, Placebo-injected eyes exhibited the highest propensity to leak, with five of six eyes leaking on FA, whereas only one of five bevacizumab-injected eyes exhibited leakage. On histological examination, all 11 eyes contained CNV membranes of similar size, regardless of treatment. The number of vascular endothelial cells was significantly reduced (p = 0.03) in CNV membranes from eyes that had been injected with bevacizumab when compared with CNV membranes from placebo-injected eyes. There was a trend towards more retinal pigment epithelium cells (p = 0.16) and fewer glial fibres (p = 0.08) in membranes from bevacizumab-treated eyes compared with placebo-treated eyes. Bevacizumab was identified immunohistochemically in the inner limiting membrane (ILM) and to a lesser degree in the remaining retina. Strong staining was also detected in both retinal blood vessels and entire CNV membranes with no cellular predisposition. Vascular endothelial growth factor expression was found in the CNV membranes, in the ILM, in the ganglion cell layer, in Müller cells throughout the neuroretina and in retinal blood vessels. Conclusions:, Bevacizumab significantly reduced the proliferation of vascular endothelial cells in CNV membranes and showed a strong trend towards a reduction of leakage from these membranes. After a single injection, bevacizumab did not exhibit a size reducing effect on CNV, but it was still present in the membranes 14 days after intravitreal injection. [source] Unilateral choroidal excavation in the macula detected by spectral-domain optical coherence tomographyACTA OPHTHALMOLOGICA, Issue 3 2010Yuka 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] Use of heavy silicone oil (Densiron-68®) in the treatment of persistent macular holesACTA OPHTHALMOLOGICA, Issue 8 2009Alexandra Lappas Abstract. Purpose:, In this retrospective case series, we studied the effect of ,heavy' silicone oil on persisting macular holes. Patients with macular holes that failed to close after conventional macular hole surgery were retreated with the longterm internal tamponade Densiron-68®. Methods:, Twelve patients with primary macular holes that persisted after pars plana vitrectomy, peeling of the internal limiting membrane and internal gas tamponade with SF6 (sulphur hexafluoride) were retreated with heavy silicone oil, Densiron-68®, in the University Eye Hospital, Cologne. After 1.5,4 months the Densiron-68® was removed. Best corrected visual acuity (VA), slit-lamp examination, binocular fundus examination and optical coherence tomography (OCT) were used for evaluation pre- and postoperatively. The follow-up period was 3,7 months. Results:, Preoperatively, all patients displayed full-thickness macular holes, with a mean size of 502.25 ,m (± 129.39 ,m). Postoperatively, 11 of 12 macular holes were closed. One patient experienced a reopening of the macular hole. Mean VA was 20/250 (1.07 ± 0.22 logMAR) prior to treatment with Densiron-68® and 20/160 (0.84 ± 0.24 logMAR) postoperatively. Visual acuity increased from baseline in nine patients and decreased in one. Conclusions:, Retreatment of persisting macular holes with the heavy, longterm tamponade Densiron-68® resulted in anatomical closure of the hole in 11 of 12 cases. This result was accompanied by a functional improvement in VA in nine of 12 patients. [source] Value of internal limiting membrane peeling in surgery for idiopathic macular hole and the correlation between function and retinal morphologyACTA OPHTHALMOLOGICA, Issue thesis2 2009Ulrik Correll Christensen MD Abstract. Idiopathic macular hole is characterized by a full thickness anatomic defect in the foveal retina leading to loss of central vision, metamorphopsia and a central scotoma. Classic macular hole surgery consists of vitrectomy, posterior vitreous cortex separation and intraocular gas tamponade, but during the past decade focus has especially been on internal limiting membrane (ILM) peeling as adjuvant therapy for increasing closure rates. With increasing use of ILM peeling and indocyanine green (ICG) staining, which is used for specific visualization of the ILM, concerns about the safety of the procedure have arisen. At present, it is not known whether ICG-assisted ILM peeling potentially reduces the functional outcome after macular hole surgery. The purpose of the present PhD thesis was to examine whether ICG-assisted ILM peeling offers surgical and functional benefit in macular hole surgery. We conducted a randomized clinical trial including 78 pseudophakic patients with idiopathic macular hole stages 2 and 3. Patients were randomly assigned to macular hole surgery consisting of (i) vitrectomy alone without instrumental retinal surface contact (non-peeling), (ii) vitrectomy plus 0.05% isotonic ICG-assisted ILM peeling or (iii) vitrectomy plus 0.15% trypan blue (TB)-assisted ILM peeling. Morphologic and functional outcomes were assessed 3, 6 and 12 months after surgery. The results show that surgery with ILM peeling, for both stages 2 and 3 macular holes, is associated with a significantly higher closure rate than surgery without ILM peeling (95% versus 45%). The overall functional results confirm that surgery for macular hole generally leads to favourable visual results, with two-thirds of eyes regaining reading vision (,20/40). Macular hole surgery can be considered a safe procedure with a low incidence of sight-threatening adverse events; the retinal detachment rate was 2.2%. Visual outcomes in eyes with primary hole closure were not significantly different between the intervention groups; however, for the stage 2 subgroup with primary macular hole closure, there was a trend towards a better mean visual acuity in the non-peeling group (78.2 letters) compared to the ICG-peeling group (70.9 letters), p = 0.06. Performing repeated macular hole surgery was associated with a significant reduction in functional outcome indicating that primary focus should be on closing the macular hole in one procedure. Morphological studies of closed macular holes with contrast-enhanced optical coherence tomography (OCT) found thinning and discontinuity of the central photoreceptor layer matrix that were highly specific for predicting the likelihood of an eye having regained reading vision 12 months after macular hole surgery. Additionally, healing after macular hole surgery appeared to begin with the contraction of the inner aspect of the retina, forming a roof over a subfoveal fluid-filled cavity, and to end with a gradual restoration of the anatomy in the outer layers of the retina at the junction of the photoreceptor inner and outer segments. We found the more intact this structure was on contrast-enhanced OCT 3 months after macular hole surgery, the better the visual acuity after 12 months, whereas late rather than early resolution of subfoveal fluid had no impact on final visual outcome. The use ILM peeling and intraoperative dyes did not have any functionally important effects on postoperative macular structure. Based on the above findings, we conclude that ILM peeling should be performed in all cases of full thickness macular hole surgery. The use of 0.05% intraoperative isotonic ICG with short exposure time appears to be a safe alternative in stage 3 macular hole surgery, whereas a slight reduction in functional potential not can be excluded when performing 0.05% isotonic ICG-assisted ILM peeling in stage 2 macular hole surgery. [source] Macular hole surgery with and without internal limiting membrane peelingACTA OPHTHALMOLOGICA, Issue 2009C KOURENTIS Purpose To compare the results of surgery for idiopathic macular hole with or without the surgical removal of the internal limiting membrane (ILM) and the effect on anatomical and functional success rates. Methods 41 consecutive patients with idiopathic macular hole stage II (n=11), III (n=22) and IV (n=8) underwent pars plana vitrectomy and intraocular gas tamponade in this study. The surgery was performed either with ILM peeling,Group A (n=28), or without, Group B (n=13). Ocular coherence tomography and ETDRS visual acuity were measured pre- and postoperatively to assess macular hole size and anatomical hole closure as well as visual function. Results The postoperative macular hole closure rate was 100% (28/28) in Group A and 84,6% (11/13) in Group B. The 2 cases that failed to close with primary surgery had a hole size greater than 400µm. There was no significant difference between the two groups in the postoperative visual outcome once anatomical success was achieved. Conclusion The study suggests that more evidence based trials are necessary to investigate the benefit of ILM peeling especially in the treatment of larger macular holes. [source] Internal limiting membrane stainingACTA OPHTHALMOLOGICA, Issue 2009J KATSIMPRIS Purpose To describe the different modalities of internal limiting membrane (ILM) staining for the treatment of idiopathic macular hole (IMH). Methods Search of the MEDLINE database by using Medical Subject Heading search terms and key words related to ILM staining, macular hole surgery. Results ILM removal has been closely related with increased closure rates. However, because of poor ILM visibility the surgical removal of ILM is very difficult and poses serious complications. To obtain better visibility of ILM some special techniques have been developed using specific dyes such as, trypan blue (TB), indocyanine green (ICG), infracyanine green or triamsinolone acetonide(TA). Anatomic success rates with one surgery have increased (>90%) however, concern for toxicity has emerged. Patients with ICG-assisted ILM peeling appear to have a depressed recovery of visual acuity compared to those not using ICG. Concentrations of ICG that are <0.5 mg/mL have been shown to be non-toxic in cultures of RPE cells. Infracyanine green is a similar molecule that does not contain iodine and is less likely to induce osmolarity related toxic effects on the PRE cells when compared to ICG. It has been used also for ILM staining in combination with trypan(TB). TB is a second generation vital dye that stains epiretinal membranes (ERMs) directly and ILM to a lesser extent. Thus TB is useful for both macular hole and macular pucker surgery. TA may be also used to help highlight the ILM, although it is not a dye. It does adhere to the posterior hyaloid, making the detection of ILM easier. Conclusion This review largely reflects the great advent of different techniques for ILM staining. The use of ICG is more toxic when compared with TB. For TA long-term effects have not been well studied. [source] Is there still a place for vitrectomy in the treatment of macular edema due to venous occlusion ?ACTA OPHTHALMOLOGICA, Issue 2009CJ POURNARAS Purpose Persistent macular edema (ME) is the main cause of poor visual outcome in either non-ischemic BRVO or CRVO. Among multiples treatment approaches, vitreoretinal surgery with the goal to achieve the recanalisation of the occluded vessels and/or the resolution of ME, were proposed. Methods Vitrectomy with peeling of the posterior hyaloid and/or the internal limiting membrane,asociated to intravitreal (IVT) triamcinolone , neurotomy, sheathotomy, intravascular rtPA injection were studied in numerous nonrandomized cases series. Results Pars plana vitrectomy has been shown to reduce macular oedema and restore the normal foveal contour without significant change in best corrected visual acuity. In contrast, visual improvement occurs after vitrectomy for vitreous haemorrhage, epiretinal membrane formation and retinal detachment complicating BRVO. Evidence to date does not support any therapeutic benefit from radial optic neurotomy, optic nerve decompression, arteriovenous crossing sheathotomy or intravascular rtPA. Vitrectomy combined with IVT triamcinolone, induces a ME decrease rapidly and durably, without any improvement in visual acuity. Conclusion Vitrectomy with IVT triamcinolne seems to have a more durable effect than IVT triamcinolone alone.Vitrectomy, A-V sheathotomy combined with intravenous t-PA may offer benefits in BRVO. Despite uncertainty and open questions, surgical interventions are likely to be a therapeutic option for RVO in the future. Randomized and controlled studies are needed to confirm these results and to compare them to the natural course of the disease. [source] Temporal changes in retinal thickness after removal of the epiretinal membraneACTA OPHTHALMOLOGICA, Issue 4 2009Hitoshi Aso Abstract. Purpose:, We aimed to study the temporal aspects of the postoperative reduction of retinal thickness in eyes with epiretinal membrane after vitrectomy with peeling of the epiretinal membrane and internal limiting membrane. Methods:, In a retrospective study performed as a non-comparative, interventional case series, 16 eyes from 15 patients with idiopathic epiretinal membrane who underwent vitrectomy and removal of the epiretinal membrane were followed up using optical coherence tomography measurements. Retinal thickness in the macular area was assessed by the foveal thickness and macular volume in a circle 6 mm in diameter. Results:, Scattergrams of the foveal thickness and macular volume were best fitted with exponential curves. The average time constants of the exponential curve for foveal thickness and macular volume changes were 31 days (range 4,109 days) and 36 days (range 5,100 days), respectively. The average expected final values for foveal thickness and macular volume were 334 ,m (range 206,408 ,m) and 7.53 mm3 (range 6.57,8.66 mm3), respectively, which were significantly greater than those in normal controls (p < 0.0001, t -test). Conclusions:, Retinal thickness decreases rapidly immediately after surgical removal of the epiretinal membrane and the reduction rate gradually slows thereafter. Approximation of the exponential curve provides an estimation of final retinal thickness after surgical removal of the epiretinal membrane; final thickness is expected to be greater than in normal eyes. [source] Clinical and Histological Aspects of CNV Formation: Studies in an Animal ModelACTA OPHTHALMOLOGICA, Issue thesis2 2008Nathan Lassota MD Abstract. The purpose of the present thesis was to develop an animal model of CNV in order to study the early formation of CNV and to test the effects of an anti-angiogenic treatment. Porcine eyes were chosen as a substrate for CNV induction, since they are similar to human eyes in terms of both macroscopic and microscopic morphology. However, a major difference is that pigs lack a fovea; instead they have a visual streak, with a relatively stable and high concentration of cones. By surgical perforation of Bruch's membrane we were able to induce formation of CNV membranes. The morphology and cellular composition of these membranes varied with the surgical technique employed. When RPE cells were locally removed at the time of perforation, the resulting CNV was thinner, contained fewer blood vessels and was less prone to leak on fluorescein angiography than when RPE cells were left intact at induction. The neuroretina overlying the perforation site was not damaged by any of the surgical techniques, thus allowing the subsequent retinal damage to be ascribed to the actual process of CNV formation. Using this animal model allowed us to directly map histological findings onto fluorescein angiograms and thereby perform meaningful correlations between histopathologic and photographic features. Such correlations have been hampered in human subjects, since human eyes are not enucleated as a consequence of CNV and are therefore only available for post-mortem studies. In such studies there often is a considerable time-gap between the death of the patient and the latest available fluorescein angiogram, thereby allowing macular pathology to evolve in the interim. Histological examination of the porcine membranes demonstrated that they were composed of RPE cells, glial cells, macrophages, endothelial cells, collagen and smooth muscle fibres, which are the same cellular and fibrillar elements that dominate human CNV membranes. The porcine model was applied to test the effects, in a randomized and masked fashion, of intravitreally injected bevacizumab. Bevacizumab, a pan VEGF A antibody, was found to reduce both the proliferation of endothelial cells in CNV membranes and the propensity to leak in fluorescein angiograms. Immunohistochemically, bevacizumab was detected in the inner limiting membrane, in retinal blood vessels and binding uniformly to the entire CNV membrane without any cellular predisposition. Based on the above findings we believe that the porcine CNV model shows a bearing to human disease and therefore might be used as a tool to obtain improved treatments for this debilitating condition. [source] Vitreous surgery for macular hole in patients with Vogt-Koyanagi-Harada diseaseCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 9 2008Izumi Kobayashi MD Abstract We describe two patients with Vogt-Koyanagi-Harada (VKH) disease, both in the convalescent stage, who presented with unilateral macular holes together with clinically significant epi-retinal membranes. Vitreo-retinal surgery was performed on the affected eyes and the surgical technique involved a standard three-port vitrectomy, peeling of the epi-retinal and internal limiting membrane (ILM). In both cases the retinae were tamponaded with air resulting in anatomical closure of the macular holes. The histology of the excised membrane was available in one case and this revealed multiple layers of presumed retinal pigment epithelial cells with cytoplasmic processes and intercellular junctions forming a basal lamina attached to the smooth surface of the ILM. Our findings demonstrate that macular holes can develop in patients with VKH but that the hole can be successfully closed with vitreo-retinal surgery. The convalescent stage tends to occur several weeks after the acute stage when the uveitic process has subsided and is characterized by choroidal depigmentation, producing a sunset glow appearance to the ocular fundus. Patients may also demonstrate varying degrees of cutaneous hypopigmentation, poliosis and/or alopecia. Macular holes have also been reported previously in patients during the convalescent stage of VKH and this communication describes the outcome of two patients who underwent vitreo-retinal surgery for this problem. [source] Protecting the retinal pigment epithelium during macular hole surgeryCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 6 2005Jeffrey L Olson MD Abstract Herein a new surgical technique used during pars plana vitrectomy with internal limiting membrane peeling for macular hole surgery is reported. Perfluorocarbon liquid is used to tamponade the macular hole in order to prevent indocyanine green contact with the retinal pigment epithelium. [source] Transepithelial elimination of cutaneous vulval granuloma inguinaleJOURNAL OF CUTANEOUS PATHOLOGY, Issue 10 2000Pratistadevi K. Ramdial Background: Transepithelial elimination (TEE), a distinct and well-known entity, is a process during which the skin eradicates undesirable or irritative dermal substances through intact epidermis or follicular epithelium by passive or active means. Although TEE is being described in an increasing number and range of pathological processes, to date, TEE of granuloma inguinale (GI) remains unrecorded in the English-language literature. The aims of this study were: 1) To appraise the light microscopic and ultrastructural morphological epidermal changes that are associated with TEE of cutaneous vulval GI; and 2) To determine the role of intra-epidermal leucocytes and histiocytes in the pathogenesis of TEE of vulval GI. Methods: This is a retrospective 9-year histopathological review of all cases diagnosed and coded as vulval granuloma inguinale in the Department of Anatomical Pathology, Nelson R. Mandela School of Medicine, University of Natal, Durban, South Africa. Ultrastructural evaluation was performed on selected cases using a Jeol transmission electron microscope. Results: Of 53 skin biopsies from 47 patients with vulval GI, 43 were suitable for the study. The age range of patients was 15,40 years (mean age=22 years). There were eleven papular, twelve nodular, seven verrucous and thirteen ulcerative lesions. Donovan bodies within macrophages, free-lying Donovan bodies and dense aggregates of neutrophils and plasma cells were seen in the dermis of all biopsies. There was consistent overlying pseudoepitheliomatous hyperplasia. The dermal inflammatory infiltrate hugged the dermo-epidermal junction and appeared entrapped between elongated and acanthotic epidermal rete ridges and pegs. Transepidermal neutrophil microabscesses, histiocytes containing Donovan bodies and neutrophilic and histiocytic fragmentation were present. A variable number of free-lying and intra-histiocytic Donovan bodies and neutrophils were present on the surface of the epidermis. On ultrastructural investigation epidermal spongiosis, intracellular oedema, free-lying, intra-neutrophilic and intra-histiocytic Donovan bodies, and intact and degenerating neutrophils and histiocytes were evident between keratinocytes. The degenerative histiocytes demonstrated marked vacuolation, mitochondrial swelling and bacilli within phagolysosomal vacuoles, bound by intact or disrupted limiting membranes. Conclusion: The inflammatory infiltrate at the epitheliomesenchymal interface, pseudoepitheliomatous hyperplasia, intra-epidermal accumulation and disintegration of neutrophils and histiocytes, and the associated release of lytic enzymes, play important contributory roles in TEE of GI. TEE of infectious agents is a poorly recognised mechanism of spread of infectious diseases and represents a public health hazard. In cutaneous vulval GI, TEE is highlighted as a hitherto unrecognised, potential method of spread of Calymmatobacterium granulomatis. [source] A role for caleosin in degradation of oil-body storage lipid during seed germinationTHE PLANT JOURNAL, Issue 6 2006Marianne Poxleitner Summary Caleosin is a Ca2+ -binding oil-body surface protein. To assess its role in the degradation of oil-bodies, two independent insertion mutants lacking caleosin were studied. Both mutants demonstrated significant delay of breakdown of the 20:1 storage lipid at 48 and 60 h of germination. Additionally, although germination rates for seeds were not affected by the mutations, mutant seedlings grew more slowly than wild type when measured at 48 h of germination, a defect that was corrected with continued growth for 72 and 96 h in the light. After 48 h of germination, wild-type central vacuoles had smooth contours and demonstrated internalization of oil bodies and of membrane containing , - and , -tonoplast intrinsic proteins (TIPs), markers for protein storage vacuoles. In contrast, mutant central vacuoles had distorted limiting membranes displaying domains with clumps of the two TIPs, and they contained fewer oil bodies. Thus, during germination caleosin plays a role in the degradation of storage lipid in oil bodies. Its role involves both the normal modification of storage vacuole membrane and the interaction of oil bodies with vacuoles. The results indicate that interaction of oil bodies with vacuoles is one mechanism that contributes to the degradation of storage lipid. [source] | |||||||||||||