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Biomedical subjects

K U Bartz-Schmidt

Publications and source records attributed to K U Bartz-Schmidt.

At least 55 records · Page 3Linked to original sources
PubMed2001

[Pseudohypopyon of cholesterol crystals occurring 16 years after retinal detachment in x-linked retinoschisis].

BACKGROUND: Cholesterol crystals of the anterior chamber can be found as a marked feature of advanced cholesterosis bulbi; typically following i. o. hemorrhage after severe trauma, retinal detachment or M. Coats. CASE REPORT: A 39-year-old male patient with longstanding (16 years) retinal detachment in his right eye due to x-chromosomal linked retinoschisis presented with a clinical picture of a hypopyon and mature cataract. Ultrasonography showed a retrolental mass. Phacolytic uveitis was suspected and pars plana lentectomy and vitrectomy was performed. Intraoperatively subretinal chrystals could be detected. A specimen of the aqueous humor and subretinal fluid was evaluated biochemically and histologically and revealed cholesterol crystals. CONCLUSIONS: Cholesterosis bulbi may be similar to lentogenic uveitis and should be included in the differential diagnosis of such processes. To our knowledge this is the first case of cholesterol crystals of the anterior chamber sixteen years after retinal detachment in x-linked retinoschisis.

Adult↗
PubMed2001

Clinicopathological correlation of retinal pigment epithelial tears in exudative age related macular degeneration: pretear, tear, and scarred tear.

AIMS: To analyse the histopathology of vascularised pigment epithelial detachments and tears of the retinal pigment epithelium (RPE) in age related macular degeneration (AMD). METHODS: The light microscopic architecture of 10 surgically removed subretinal specimens-three vascularised pigment epithelial detachments, four recent tears, and three scarred tears as a manifestation of AMD-were studied and correlated with the angiographic findings. RESULTS: Recent tears: a large fibrovascular membrane was found to be originally situated in Bruch's membrane. About half of the surface of the fibrovascular tissue was denuded of RPE and diffuse drusen. The RPE and diffuse drusen had retracted and rolled up, covering a neighbouring part of the intra-Bruch's fibrovascular membrane. The rolled up RPE and diffuse drusen were not interspersed with fibrovascular tissue but lay superficial to the intra-Bruch's fibrovascular membrane itself. Scarred tears: a collagen capsule surrounded the rolled up diffuse drusen and RPE. Fibrovascular tissue was found inside the rolled up material, predominantly at its choroidal side. CONCLUSION: The area of choroidal neovascularisation associated with a vascularised pigment epithelial detachment and a tear of the RPE may be larger than was hitherto thought or indicated by fluorescein angiography. This neovascular tissue may be present within the bed of the RPE tear, as well as at the site of the scrolled up RPE.

Aged↗
PubMed2001

Electrophysiological changes after 360 degrees retinotomy and macular translocation for subfoveal choroidal neovascularisation in age related macular degeneration.

AIM: To evaluate electrophysiological changes after 360 degrees retinotomy and macular translocation for subfoveal choroidal neovascularisation in patients with age related macular degeneration (AMD). METHODS: A consecutive series of 32 patients suffering from subfoveal choroidal neovascularisation secondary to AMD underwent 360 degrees retinotomy and macular translocation. The ERG served as the main parameter of the study and was recorded 1 day before the translocation surgery and no earlier than 4 weeks after the silicone oil removal. RESULTS: The scotopic ERG amplitudes were significantly reduced after translocation surgery. Depending on the applied flash luminance the mean b-wave amplitude reduction of the scotopic ERG varied between 67% (0.2 cd.s/m2) and 74% (0.03 cd.s/m2). The a-waves and b-waves of the saturating light response decreased significantly by 46% and 59%, respectively. The photopic a-wave and b-wave amplitudes were significantly lower after the translocation surgery resulting in a mean reduction of 27% and 43%, respectively. CONCLUSIONS: Although macular translocation may provide the potential of preserving and even restoring vision in patients with subfoveal choroidal neovascular membranes secondary to AMD the present study indicates that a significant electrophysiological decrease is caused by surgical procedures associated with this technique. Further research is necessary to clarify if certain modifications of the surgical procedure are able to substantially reduce the neuroretinal trauma.

Aged↗
PubMed2001

Oxidation causes melanin fluorescence.

PURPOSE: The goal of this study is the characterization of the strong yellow fluorescence of oxidized melanin in the retinal pigment epithelium (RPE) and the choroid. METHODS: Naturally occurring melanin in the human retina and choroid was oxidized by exposing fixed and plastic-embedded sections of a human eye to light and hydrogen peroxide. Synthetic melanin was also oxidized in vitro by exposure to light and hydrogen peroxide. The fluorescence of oxidized melanin was examined by absorption spectroscopy, fluorescence spectroscopy, and fluorescence microscopy. RESULTS: Naturally occurring melanin oxidized in situ exhibited a lipofuscin-like yellow fluorescence. Oxidation of melanin in vitro degraded the melanin polymer, resulting in a fluorescent solution. Fluorescence spectroscopy gave an excitation maximum at approximately 470 nm and an emission maximum at approximately 540 nm for both natural and synthetic melanin. Increasing the time of exposure to light or hydrogen peroxide increased melanin fluorescence. CONCLUSIONS: The results indicate that the strong yellow fluorescence of melanin in the RPE and choroid in situ is a property of oxidized melanin and is not due to contamination of the melanin by proteinaceous or lipid materials. The data presented allow a reinterpretation of the results obtained from fluorescence investigations of melanin-containing tissue and suggest a link between melanin degradation and lipofuscin formation.

Choroid↗
PubMed2001

Subretinally transplanted embryonic stem cells rescue photoreceptor cells from degeneration in the RCS rats.

The Royal College of Surgeons (RCS) rat is an animal model for retinal degeneration such as the age-related macular degeneration. The RCS rat undergoes a progressive retinal degeneration during the early postnatal period. A potential treatment to prevent this retinal degeneration is the transplantation into the subretinal space of cells that would replace functions of the degenerating retinal pigment epithelium (RPE) cells or may form neurotrophic factors. In this study we have investigated the potential of subretinally transplanted embryonic stem cells to prevent the genetically determined photoreceptor cell degeneration in the RCS rat. Embryonic stem cells from the inner cell mass of the mouse blastocyst were allowed to differentiate to neural precursor cells in vitro and were then transplanted into the subretinal space of 20-day-old RCS rats. Transplanted and sham-operated rats were sacrificed 2 months following cell transplantation. The eyes were enucleated and photoreceptor degeneration was quantified by analyzing and determining the thickness of the outer nuclear layer by light and electron microscopy. In the eyes transplanted with embryonic cells up to 8 rows of photoreceptor cell nuclei were observed, whereas in nontreated control eyes the outer nuclear layer had degenerated completely. Transplantation of embryonic stem cells appears to delay photoreceptor cell degeneration in RCS rats.

Animals↗
PubMed2000

Transplantation of autologous iris pigment epithelium after removal of choroidal neovascular membranes.

BACKGROUND: Transplantation of autologous iris pigment epithelium (IPE) into the subretinal space has been suggested as one approach for the treatment of age-related macular degeneration, as well as for other conditions in which loss of retinal pigment epithelium (RPE) occurs. Surgical removal of choroidal neovascular membranes is associated with traumatic loss of the RPE cell layer, disruption of the integrity of the photoreceptor-RPE complex, and limited visual outcome. OBJECTIVE: To examine whether IPE cells can substitute for RPE cells to be transplanted to the subretinal space of patients with either RPE degenerative disease or traumatic loss of the RPE cell layer after subretinal surgery. METHODS: Autologous IPE cells were transplanted to the subretinal space in 20 consecutive patients undergoing removal of subretinal fibrovascular membranes using pars plana vitrectomy. Autologous IPE cells were harvested by iridectomy, isolated, and transplanted directly to the subretinal spaces. Transplants were evaluated for 6 to 11 months by funduscopy, fluorescein angiography, and scanning laser ophthalmoscopic (SLO) microperimetry. RESULTS: For the entire follow-up period, no evidence of any immunologic response was observed. Revisional surgery was necessary in 3 patients because of complications (rhegmatogenous retinal detachment [n = 1]; proliferative vitreoretinopathy [n = 1]; and macular pucker [n = 1]); 1 patient did not receive IPE cells. Five of 19 phakic eyes underwent cataract surgery; in 1 case this was combined with the vitrectomy. Five patients showed improved visual acuity of 3 to 4 lines, 13 patients had stable visual acuity (+/-2 lines), and 2 patients had reduced visual acuity of 6 lines. CONCLUSIONS: In this pilot study, the transplantation of autologous IPE cells was done as an addition to conventional surgical excision of choroidal neovascular membranes. Transplanted cells were well tolerated in the subretinal space and did not adversely affect the function of the photoreceptors, since improvement or stable visual acuity was observed in 18 patients after IPE transplantation. These results suggest that autologous IPE cells may be used as a substitute for autologous RPE cells to transplant to the subretinal space to treat age-related macular degeneration.

Adult↗
PubMed2000

Counterrotation of the globe in macular translocation.

BACKGROUND: Macular translocation is a new treatment option in age-related maculopathy. The aim of this study was to report experience with the handling of the sensory problems concerning subjective cyclorotation and binocularity that arise with this technique. METHODS: The data of 33 patients who had undergone macular translocation and counterrotation of the globe by muscle surgery in a first operation, followed by silicone oil removal and sometimes revision of the eye muscles in a second operation, were evaluated. The counterrotation consisted of a partial transposition of the rectus muscles and extensive surgery on the anterior margins of the oblique eye muscles. Subjective monocular cyclorotation, motility and binocularity were tested. RESULTS: In 5 patients after the two operations binocular single vision was proved; in one of these cases there was even stereoscopic function. Seventeen patients excluded one eye: 13 excluded the operated eye, 4 the fellow eye. Eleven patients experienced double vision or tilted images under binocular viewing conditions and thus required further surgery or occlusion of one eye. CONCLUSION: The majority of patients were not hindered by subjective cyclorotation. Nevertheless, in a large proportion of patients binocularity could not be reestablished because of still reduced visual acuity or cyclotropia. The data show that the aim of restoring binocularity can be achieved but in practice is often not attained.

Aged↗
PubMed2000

Transplantation of iris pigment epithelium into the choroid slows down the degeneration of photoreceptors in the RCS rat.

BACKGROUND: Trophic factors [e.g. basic fibroblast growth factor (bFGF)] released by transplanted retinal pigment epithelial (RPE) cells are able to slow down the hereditary degeneration of the retina in the Royal College of Surgeons rat in sites distant from the site of transplantation where rod outer segment (ROS) phagocytic activity is not reconstituted by the transplants. METHODS: To investigate whether iris pigmented epithelial (IPE) cells are also able to generate this rescue by trophic factors, we transplanted IPE cells from Long-Evans rats into the choroid and subretinal space of 17 young RCS rats. The eyes were enucleated after 6 months and prepared for light microscopy. Six age-matched RCS rats served as controls. Light microscope sections from the whole choroid, healthy choriocapillaris, transplanted cells and the maximum thickness of the choroid, and outer nuclear layer parameters were analyzed by computer-assisted morphometry. RESULTS: In transplanted animals photoreceptor cells were rescued from degeneration although the majority of the transplanted IPE cells were located in the choroid. In the non-transplanted group photoreceptors were absent. CONCLUSIONS: Transplantation of IPE cells slows down degeneration of the photoreceptors in the RCS rat. This photoreceptor-sparing effect by the IPE cells was observed even when the transplants were predominantly located within the choroid. The beneficial effect observed may be related to trophic factors possibly secreted by the transplanted IPE cells.

Animals↗
PubMed2000

[Significance of postoperative face-down positioning after surgery for idiopathic macular holes: consecutive case-control study].

BACKGROUND: Postoperative face-down positioning is considered to be a critical part in macular hole surgery with short-acting gas. However, the significance of this posturing remains uncertain using long-acting gas tamponade. PATIENTS AND METHODS: Fifty consecutive eyes with idiopathic full-thickness macular holes underwent macular hole surgery with a follow up time of 6-12 months. The results of a cohort (25 eyes) with complete C3F8 (16%) vitreous fill without posturing was compared to a cohort (25 eyes) with SF6 (20%) with strict postoperative face-down positioning for two weeks. RESULTS: With SF6 tamponade the anatomic success rate was 64% in the C3F8 cohort a complete closure was achieved in 88%. In the SF6 cohort, visual recovery of three lines or better was attained in 44%, resulting in a visual acuity of 20/50 or better in 12%. The mean postoperative visual acuity was 20/125 with a mean rise of 1.4 lines. In the C3F8 cohort, 72% improved for at least three lines with a mean postoperative visual acuity of 20/63 and a mean visual recovery of 3.3 lines. Visual acuity of 20/50 or better was noted in 48% of eyes. CONCLUSION: The significantly higher success rate using C3F8 tamponade without positioning compared to SF6 gas tamponade with positioning confirms the cumulative tamponade duration being a crucial factor in macular hole surgery. Using a tamponade with short-acting gas only strict postoperative positioning ensures the contact of the gas bubble with foveal tissue and gains significance with reducing bubble size. While a potential for significant visual recovery in certain cases is evident, all in all a broad variability of the postoperative success rate can be stated. In contrast, even in supine position C3F8 attains a continuous tamponade enforcing a sufficient glial wound healing without any positioning.

Aged↗
PubMed2000

Influence of membrane differential filtration on the natural course of age-related macular degeneration: a randomized trial.

PURPOSE: Membrane differential filtration is able to optimize rheologic parameters by eliminating high molecular weight proteins and lipoproteins from the blood. Following the hypothesis that these changes result in an improvement of the microcirculation, the authors tested the efficacy of membrane differential filtration in improving visual function in patients with age-related macular degeneration (ARMD). METHODS: Forty patients (40 eyes) were randomized into two groups. The treatment group was treated five times over a period of 21 weeks. In both groups, 9/20 of the eyes showed subfoveolar subretinal neovascularization. The main parameter of the study was visual acuity (VA). Electroretinogram (ERG), electrooculogram, and macular visual evoked potentials were also recorded. Plasma and whole blood viscosity and erythrocyte aggregation were measured. RESULTS: The 20 patients treated repeatedly over a period of 21 weeks showed a mean improvement of 0.63 lines (SD 1.8) of VA on Early Treatment Diabetic Retinopathy Study charts. The control group showed a deterioration of 0.94 lines (SD 1.7) compared to VA at baseline examination. The amplitude of the ERG photopic a-wave and the flicker ERG was significantly increased. The rheologic parameters were lowered in all treated patients. CONCLUSION: Repetitive treatment with membrane differential filtration is able to improve visual acuity of patients with ARMD and the natural course of this disease. Several questions arise from the results of this study. Further research will show if it is possible to optimize the selection of patients for subgroups with predictive responses through morphologic and functional tests and how to create an optimized and individual treatment strategy determined by the quality, intensity, and frequency of treatment sessions.

Aged↗
PubMed2000

Polypoidal choroidal vasculopathy pattern in age-related macular degeneration: a clinicopathologic correlation.

PURPOSE: To report the histopathologic features of surgically removed submacular tissue from an elderly patient with a pattern of polypoidal choroidal vasculopathy on indocyanine green angiography. METHODS: Clinical examination including fluorescein and indocyanine green angiography and light microscopy of surgical specimen. RESULTS: A thick yellow proteinaceous subretinal fluid was seen in the right macula of an 81-year-old white man. Fluorescein angiography indicated progressive leakage from undetermined source apart from a few focal hyperfluorescent points. Indocyanine green angiography showed several polyps as well as dilated choroidal vessels in the macula and along the superior temporal arcade. A large plaque was visualized in the late phase. Microscopically, the specimen consisted of a thick fibrovascular membrane located on the choroidal side of the retinal pigment epithelium (RPE). The RPE layer was discontinuous whereas on its choroidal side an almost intact layer of diffuse drusen was observed. A group of dilated thin-walled vessels were found that appeared to be saccular on serial sections. Some of these were located almost immediately under the diffuse drusen. CONCLUSION: Histologic examination of submacular tissue removed from an eye with polypoidal choroidal vasculopathy showed several aneurysmal dilatations located directly under diffuse drusen within a sub-RPE, intra-Bruch's fibrovascular membrane.

Aged↗
PubMed2000

Clinicopathological correlation of deep retinal vascular anomalous complex in age related macular degeneration.

AIMS: To analyse the histopathology of "deep retinal vascular anomalous complex" or "chorioretinal anastomosis". METHODS: Six patients with a deep retinal vascular anomalous complex (age range 66-88 years) had fundus photography and fluorescein angiography not more than 14 days before foveal translocation surgery. Four patients were also documented with indocyanine green angiography. The surgical specimens were serially sectioned and stained in a stepped fashion with Masson trichrome, periodic acid Schiff, and phosphotungstic acid haematoxylin, a histochemical stain for fibrin. RESULTS: A subretinal fibrovascular membrane was surrounded by a rim consisting of diffuse drusen (basal laminar deposits), retinal pigment epithelium, and amorphous, fibrinous material interspersed with remains of outer segments in all specimens. In two specimens vascular structures were identified that left the specimen towards the retina. Amorphous material with the remains of outer segments was not found on the retinal side of the fibrovascular tissue itself but in four specimens a small neuroretinal portion (outer nuclear layer) was adherent to the complex. In three specimens a thin fibrocellular membrane was seen at the choroidal side of the diffuse drusen. CONCLUSION: Deep retinal vascular anomalous complex represents histologically neovascularisation growing out of the neuroretina, into the subretinal space, which mimics choroidal neovascularisation. The term therefore appears rightly chosen.

Aged↗
PubMed2000

Clinicopathological correlation in exudative age related macular degeneration: histological differentiation between classic and occult choroidal neovascularisation.

AIMS: To analyse the histopathology of classic and occult choroidal neovascular membrane surgical specimens in age related macular degeneration. METHODS: 35 membranes, from a consecutive series of surgically removed choroidal neovascular membranes in age related macular degeneration, were classified as classic or occult following the guidelines of the Macular Photocoagulation Study. Membranes with classic as well as occult components were considered as mixed membranes. The membranes were serially sectioned and stained with haematoxylin and eosin, Masson trichrome, periodic acid-Schiff, and phosphotungstic acid haematoxylin stain. The correlation has been made in a masked fashion. RESULTS: 31 membranes (19 classic, 10 occult, and two mixed membranes) could be analysed histologically. 18 classic choroidal neovascular membranes had a major subretinal fibrovascular component and 10 of these had an additional, minor fibrovascular component under the retinal pigment epithelium. The 10 occult membranes contained a fibrovascular component under the retinal pigment epithelium and the two mixed membranes contained fibrovascular tissue on both sides of the retinal pigment epithelium. Fibrin and remains of outer segments tended to occur at the lateral edges of classic membranes and to cover the inner surface of occult membranes. CONCLUSION: Classic choroidal neovascularisation in age related macular degeneration is predominantly composed of subretinal fibrovascular tissue while occult choroidal neovascularisation is composed of fibrovascular tissue at the choroidal side of the retinal pigment epithelium.

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PubMed2000

Adjunctive hyperbaric oxygenation in macular edema of vascular origin.

Macular edema (ME) is a primary reason for permanent decreases of visual acuity (VA) in diabetic retinopathy and retinal vein occlusions. The standard treatment (photocoagulation, rheological treatment) provide only a limited success. We have therefore studied the additional use of hyperbaric oxygenation (HBO2) in patients with persistent ME. Five patients (1 female, 4 male; 7 eyes) were treated by adjunctive HBO2. The average age of the patients was 60.6 (38.9-76.8) yr. The VA was measured with Early Treatment Diabetic Retinopathy Study charts before and after HBO2 with a monthly follow up. Fluorescein angiography was performed before and after HBO2 with a follow up every 3 mo. Each patient received 10-30 HBO2 treatments (median 15). The follow-up period was 15 mo. for every patient. The mean increase in VA was 3.5 (2-4) lines after HBO2. Retinal photocoagulation was performed in six eyes. Diabetic macular edemas showed no morphologic change, while ME originating from retinal vein occlusions (CME) regressed. The VA in our patients with ME of vascular origin seemed to improve with HBO2. Photocoagulation was necessary in most cases. Visual function correlated with the angiographic presentation only for CME.

Acetazolamide↗
PubMed1999

External beam radiotherapy for subretinal neovascularization in age-related macular degeneration: is this treatment efficient?

PURPOSE: Control of the natural course of subretinal neovascularization (SRNV) in age-related macular degeneration (AMD) is difficult. Only a subset of patients is suitable for laser coagulation. This prospective study aimed to determine the efficacy and individual benefit of external beam radiotherapy (EBRT). METHODS AND MATERIALS: The prospective trial included 287 patients with subfoveal neovascularization due to AMD which was verified by fluorescein angiography. Patients have been treated between January 1996 and October 1997. All patients received a total dose of 16 Gy in 2-Gy daily fractions with 5-6 MeV photons based on computerized treatment planning in individual head mask fixation. This first analysis is based on 73 patients (50 women, 23 men, median age 74.3 years), with a median follow-up of 13.3 months and a minimum follow-up of 11 months. RESULTS: All patients completed therapy and tolerability was good. First clinical control with second angiography was performed 6 weeks after irradiation, then in 3-month intervals. Eighteen patients with SRNV refusing radiotherapy served as a control group and were matched with 18 irradiated patients. After 7 months median visual acuity (VA) was 20/160 for the irradiated and 20/400 for the untreated patients. One year after radiotherapy final median VA was 20/400 in both groups. CONCLUSION: These results suggest that 16 Gy of conventionally fractionated external beam irradiation slows down the visual loss in exudative AMD for only a few months. Patients' reading vision could not be saved for a long-term run.

Aged↗
PubMed1999

Transplantation of autologous iris pigment epithelium to the subretinal space in rabbits.

BACKGROUND: Transplantation of autologous iris pigment epithelium (IPE) into the subretinal space has been suggested as one approach for the treatment of age-related macular degeneration. Autologous rabbit IPE cells were transplanted to the subretinal space to define the technique of transplantation and examine the survival of the transplanted cells. METHODS: Autologous IPE cells were harvested by iridectomy and transplanted directly to the subretinal space of the fellow eye in 25 rabbits, using the parsplana approach. Animals were killed over a period of 5 months, and the retinas were examined morphologically by light and electron microscopy. RESULTS: Autologous IPE cells survived and formed a polarized monolayer above the retinal pigment epithelium in the subretinal space, with apical microvilli adjacent to photoreceptors. Fragments of phagocytosed photoreceptor rod outer segments were observed in phagosomes in the cytoplasm of IPE cells. Adjacent rod outer segments remained healthy throughout the experimental period. No signs of a cell-mediated immunologic response were observed. CONCLUSIONS: Our results show that in rabbits, autologous IPE cells transplanted to the subretinal space survive and do not adversely affect the photoreceptors. These results suggest that in humans, IPE cells might provide a substitute for retinal pigment epithelium cells as autologous transplants for the treatment of age-related macular degeneration.

Animals↗