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At least 919 records · Page 51Linked to original sources
PubMed1989

Transplanted retinal pigment epithelium modifies the retinal degeneration in the RCS rat.

Transplantation of dissociated retinal epithelial cells obtained from the retinas of normal, congenic pigmented strain of rats to Bruch's membrane and the subretinal space of dystrophic rats from the Royal College of Surgeon (RCS) strain can prevent photoreceptor cell degeneration in this retina for at least 4 months after transplantation. Host and transplant cells form close apposition with one another but can be distinguished by the presence of both phagosomes and melanin granules in the transplant and the absence of these inclusions in the host retinal epithelium. Transplanted cells show excessive amounts of phagosomal material within 48 hr after transplantation, implying that restoration of phagocytosis is responsible for the photoreceptor survival.

Animals↗
PubMed1987

Simulation of a retinal scotoma by a stabilized retinal image.

Two methods are described for simulating a retinal scotoma by means of a stabilized retinal image, hence allowing some aspects of the impairment of visual function associated with scotomas to be studied in observers with normal visual fields. In the first method, an optical lever arrangement is used to generate a small artificial scotoma at a controllable position with 15 degrees field of view. The second, direct attachment, method uses a tight-fitting scleral contact lens, to which is attached a very light, aluminium-alloy tube. This carries a small piece of lightweight black card, the stabilized image of this card generating the scotoma. Although precise positioning of the scotoma is more difficult with the second method, the induced scotoma is absolute and the method is relatively cheap and easy to implement.

Contact Lenses↗
PubMedDate not supplied

Retinal angiomatous mass. A complication of retinal detachment surgery.

Retinal angiomatous masses were observed as a very late complication in four patients following scleral buckling procedures with drainage of subretinal fluid. The lesions manifested 5-19 years after the original surgical procedure, and the presenting complaint was decreased vision secondary to vitreous clouding. In three patients a vascularized retinal mass greater than 3 disc diameters in size was observed at the site of choroidal perforation for drainage of subretinal fluid. A fourth patient demonstrated a similar lesion in the location of a suture used to anchor the encircling element, possibly the point of accidental choroidal perforation. Three of the four patients were treated by photocoagulation or cryocoagulation with cicatrization of the angiomatous mass and obliteration of the vascular net. This resulted in clearing of vitreous opacities and subretinal exudates, with restoration of vision to a level prior to the onset of symptoms.

Adult↗
PubMed1978

[Suppression and therapy of experimental autoimmune uveo-retinitis by injections of retinal extract (author's transl)].

The uveo-retinitis induced in guinea-pigs after one injection in the foot-pad of an extract of guinea-pig retina mixed with Freund's complete adjuvant (FCA) was successfully inhibited by a series of injections of the retinal extract. These injections were given after the induction by the antigen + FCA, either before (suppression) or after (treatment) the onset of the ocular symptoms. Injections of the antigenic preparation alone, or mixed with Freund's incomplete adjuvant were effective. Depression of cutaneous delayed hypersensitivty was parallel to the inhibition of the disease. The repeated injections provoqued an increase of antibodies, titrated either with the complement fixation test or by passive cutaneous anaphylaxis. But no correlation appeared between these antibodies and the inhibition of the disease.

Animals↗
PubMed1982

Glycosaminoglycan synthesis by cultured human retinal pigmented epithelium from normal postmortem donors and a postmortem donor with retinitis pigmentosa.

Cultured human retinal pigmented epithelium (RPE) synthesized and secreted glycosaminoglycans (GAGs) with the characteristics of chondroitin sulfate, dermatan sulfate, and hyaluronic acid from radioactive precursors. Cells subcultured for up to 18 passages from normal RPE and from the RPE of a patient with X-linked retinitis pigmentosa synthesized and secreted the same types and proportions of GAGs as primary cultures of normal RPE. Extracts of native human interphotoreceptor matrix contained hyaluronic acid and chondroitin sulfate but little or no dermatan sulfate, and the chondroitin sulfate differed in electrophoretic mobility and enzyme susceptibility from the chondroitin sulfates secreted by cultured RPE. Cultured human choroidal cells and cultured human skin fibroblasts secreted a much higher proportion of hyaluronic acid than cultured RPE. This study demonstrates that the profile of GAGs synthesized from radioactive precursors and secreted by cultured human RPE is a specific and stable characteristic of these cells that is retained even after extensive proliferation in vitro.

Adolescent↗
PubMed1994

Progressive retinal atrophy: a model for retinitis pigmentosa in companion animals.

The generalised progressive atrophies (PRA's) are a heterogeneous group of inherited retinopathies in dogs and cats. They show marked similarities to the retinitis pigmentosas (RP) in man, as well as to a number of inherited retinal degenerations of laboratory rodents. Of the various recessively inherited forms of PRA in the dog, that in the Irish setter is due to a nonsense mutation in the gene encoding cGMP-PDE-beta subunit. Mutations at this locus are also known to cause a proportion of human RP cases. We are interested in applying gene therapy to these diseases.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1977

Retinal ultrastructure in advanced retinitis pigmentosa.

An ultrastructural study of the retina of a patient with advanced retinitis pigmentosa revealed an orderly process of cone degeneration with more advanced stages in the perifovea and less advanced stages in the fovea. No rod photoreceptors were seen. Remaining cones had enlarged nuclei with autophagic vacuoles and bundles of parallel undulating 12 nm. filaments in the cytoplasm. In the foveola and fovea, cone outer segments were very truncated or absent, although synaptic pedicles were intact. In the perifovea, many cone cell bodies were rounded with loss of synaptic pedicles. Pigment epithelial cells underlying remaining cones were enlarged with apically displaced nuclei, occasional phagosomes, and large amounts of melanolysosomes. The pigment epithelial cell layer anterior to the perifovea contained flattened pigment epithelial cells without melanolysosomes and macrophage-like cells without pigment. Pigment-laden epithelial cells around atrophic blood vessels in the midperipheral retina showed only round pigment granules unlike the smaller elongated pigment granules observed in retinal pigment epithelial cells in situ. The advanced stage and structural abnormalities in both photoreceptors and pigment epithelial cells preclude assigning a primary site for the defect.

Adult↗
PubMed1976

Specific retinal breaks in aphakic retinal separation.

The frequency and location of specific retinal breaks in a consecutive series of 169 phakic and 121 aphakic primary nontraumatic rhegmatogenous retinal separations categorized into lattice and nonlattice groups was determined. Small horseshoe tears in the oral region of the retina at the posterior vitreous base were responsible for 44.1% of aphakic nonlattice detechments. Aphakic detachments associated with lattice degeneration had a greater relative frequency of associated nonlattice tractional breaks in addition to lattice breaks.

Aged↗
PubMed1975

Retinal pigment epithelial degeneration, partial retinal atrophy and macular hole in acute lymphocytic leukemia.

A seven year old child with acute lymphocytic leukemia presented at autopsy with a macular hole, and degeneration of the retinal pigment epithelium and its overlying photoreceptors. She had been treated with cobalt 60, methotrexate, vincristine cyclophosphamide and prednisone. A review of the literature of similar findings as well as pigment epithelial degenerations from other causes is presented.

Antineoplastic Agents↗
PubMedDate not supplied

Growth factors in retinal diseases: proliferative vitreoretinopathy, proliferative diabetic retinopathy, and retinal degeneration.

The goal of this review is to present the current knowledge on specific growth factor involvement in posterior segment eye disease. Growth factors can be defined as multifunctional signals which modify cell growth or proliferation, alone or in concert, by binding to specific cell surface receptors. Their biological effects on cells include cell adhesion, migration, survival, differentiation, extracellular matrix secretion, protease and protease inhibitor release, production of other growth activities, and angiogenesis. Growth factors couple the cell to the microenvironment. As some growth factors are soluble mediators of wound repair and angiogenesis, it seems possible that proliferative vitreoretinopathy and proliferative diabetic retinopathy are caused or aggravated by these factors. Other factors act as survival factors and can possibly prevent retinal degeneration. The multifunctional nature of growth factors makes it probable that practical uses will be found for these agents in the future.

Diabetic Retinopathy↗
PubMed1989

Vitrectomy for complicated retinal detachments secondary to branch retinal vein occlusions.

Combined rhegmatogenous and traction retinal detachments associated with branch vein occlusions occurred in five eyes of five patients between Jan. 1, 1986 and Dec. 31, 1987. Four patients underwent surgery with pars plana vitrectomy and intravitreal gas, with or without scleral buckling. One patient refused treatment. All operated on eyes had attached retinas at a mean follow-up of seven months. Because posterior traction plays an important role in these unusual detachments, consideration should be given to pars plana vitrectomy and air-fluid exchange rather than scleral buckling alone.

Adult↗
PubMed1991

[Peripheral retinal streaks. Linear depigmentation of the peripheral retinal pigment epithelium].

An unusual peripheral depigmented streak lesion of the retina is described in three patients. This depigmented line is located in the equatorial region running parallel to the ora serrata and seems to result from a focal reduction or loss of pigmentation in the retinal pigment epithelium. Similar lesions have been reported as a symptom of the presumed ocular histoplasmosis syndrome (POHS) called linear streaks of the equator. As we did not find any additional symptoms of POHS in our patients, the aetiology of this peripheral depigmented streaks remains unclear.

Aged↗
PubMed1993

An anatomical study of retinal arteriovenous crossings and their role in the pathogenesis of retinal branch vein occlusions.

To elucidate the anatomical features which predispose artery over vein (AV) crossings to be the preferential sites for retinal branch vein occlusions (RBVO), 11 AV and six vein over artery (VA) crossings in 12 eyes from non-hypertensive donors who were aged 35 to 82 years, were studied by light and electron microscopy. At AV crossings the veins were often observed to abruptly alter direction to pass under the artery. Here focal stratification of the vein basement membrane opposite the point of contact with the artery was seen. A focal reduction in the vein lumen occurred at three of 11 AV crossings. In contrast, deviation of the vein, focal basement membrane stratification or focal narrowing was not seen at VA crossings. Both types of crossings had a common adventitial sheath when each vessel was of large calibre. This study demonstrated anatomical features which predispose AV crossings to be the preferential site for venous occlusion.

Adult↗
PubMed1989

Temporal branch retinal vein obstruction masquerading as a retinal arterial macroaneurysm: the Bonet sign.

We present the case report of a patient with a hemorrhage at an arteriovenous crossing which was erroneously interpreted as being an arterial macroaneurysm. Shortly thereafter, the typical appearance of a temporal branch retinal vein obstruction was evident indicating that the hemorrhage was an early sign of the venous obstruction. This sign (the Bonet sign) should alert the clinician to this disorder so that the correct diagnosis and recommendations for patient care can be undertaken.

Aged↗
PubMedDate not supplied

[Idiopathic macular edema, macular hole, retinal detachment and retinal fibrosis as complications of the involutional vitreoretinal syndrome].

The author suggests calling the involution vitreoretinal syndrome a characteristic symptom complex of vitreoretinal changes occurring in advanced age. He distinguishes three stages in the course of this syndrome an early one, whose signs are, among other things, destruction of the anterior segment of the vitreous body, presence of glial plaques of the retina (coin-shaped and flap reflexes of the fundus oculi), and changes of the posterior lenticular capsule in the lentivitreoretinal form of the syndrome. The mature stage is characterized by total destruction of the vitreous body or its detachment, transformation of a part of glial plaques into individual foci of fibrosis, phacosclerosis of lenticular nucleus. The present communication sums up complications of the syndrome occurring in the third stage of the disease. In 44 of the 109 patients the following complications were observed: macular edema in 6, macular opening in 9, reticular fibrosis in 9, retinal detachment in 8, nuclear cataract in 12. The author explains so high an incidence of complications by the fact that involutional vitreoretinal syndrome cannot be diagnosed at the early stages and that patients come to consult a doctor only when complications are developing as a rule. Physicians' awareness of the early signs of the syndrome may become an essential factor in the prevention of quite a number of intraocular conditions developing in advanced age.

Aged↗
PubMed1996

Practical community screening for diabetic retinopathy using the mobile retinal camera: report of a 12 centre study. British Diabetic Association Mobile Retinal Screening Group.

OBJECTIVE: To document the performance of 12 diabetes eye screening units in different health districts which were financed by a single charitable donation. DESIGN: Each location was equipped with a retinal camera and screening vehicle, and the lead clinician developed the screening service configuration to suit local conditions. SETTINGS: Districts were chosen on the basis of interest in developing effective diabetes eye screening services. Characteristics of districts varied from largely rural to exclusively urban. SUBJECTS: People with diabetes who attended either general practice or hospital diabetes services were screened. MAIN OUTCOME MEASURES: Referral for ophthalmological opinion and use of laser therapy for new vessel formation or exudative maculopathy. RESULTS: A total of 64,905 screening episodes were recorded. Full data were available on 42,803 episodes which led to 2400 referrals (5.6%) and 516 of which resulted in laser therapy (1.2% of those screened or 21.5% of those referred). Where sequential data were available a year by year fall in sight threatening retinopathy incidence was demonstrated as the screening programmes detected incipient problems in the initial cycles of screening. The average cost of screening was Pounds13.11 per patient and the average cost of identifying a person requiring laser therapy was Pounds1110. Financial responsibility for running the service has been taken on by 10 of the 12 health districts. CONCLUSIONS: Diabetes eye screening using a mobile retinal camera is effective, efficient and robust. It is important that the service specification is designed to suit the geography and existing diabetes services in each district.

Costs and Cost Analysis↗
PubMed1996

The properties of retinal pigment epithelial cells in proliferative vitreoretinopathy compared with cultured retinal pigment epithelial cells.

Retinal pigment epithelial (RPE) cells, which proliferate and dedifferentiate under several pathological conditions, and cultured RPE cells have been considered a good model for comparison. In this investigation, we compared the properties of RPE cells in proliferative vitreoretinopathy with that of cultured human RPE cells. mRNAs of RPE cells from patients with proliferative vitreoretinopathy and from cultured human RPE cells were extracted, and reverse transcriptase-polymerase chain reaction was performed. We also examined cells that were aspirated from bare RPE surface from a patient with a giant retinal tear. We amplified the interleukin-6 gene in the proliferative membranes and cultured RPE cells. We also amplified the tyrosinase gene in seven of eight proliferative membranes, as well as tyrosinase-related proteins and cellular retinaldehyde-binding protein genes, but not the tyrosinase gene in cultured RPE cells. The cells aspirated from bare RPE surface showed reduced activity for expressing interleukin-6 and tyrosinase genes. The dedifferentiation characteristics of cultured RPE cells were different, in that they were less active than RPE cells in proliferative membranes for expressing the genes of melanogenesis, which are essential for pigment cells. Interleukin-6 and genes that were related to melanogenesis were expressed in the proliferative membranes and may play an important role in the generation of proliferative vitreoretinopathy.

Actins↗
PubMed1997

Exogenous application of gangliosides changes the state of excitability of retinal tissue as demonstrated by retinal spreading depression experiments.

Gangliosides are amphiphilic, sialic acid-containing glycosphingolipids which are found preferentially in complex composition in the cellular membranes of the nervous system of vertebrates, including the vertebrate retina as well as in other membranes. They are always exposed to the extracellular side of the membranes. By virtue of the negative charges they carry at their headgroup, they contribute to the surface charge of the membrane and may affect ion distribution, mainly that of protons and calcium ions, at the outer side of the membranes. Using retinal spreading depression (RSD) as a tool, we show in this study that the addition of exogenous gangliosides to the extracellular space can change the state of excitability of the retinal tissue. In RSD experiments it reduces the propagation velocity as well as the intrinsic optical signal of RSD waves. These effects are concentration dependent (IC50 about 20 microM) and increase with the increasing negative charge of the ganglioside headgroup. As a possible mechanistic basis of the changes found, the change of the calcium homeostasis of the extracellular space by the exogenously added gangliosides is discussed. Gangliosides have been reported to be useful in the treatment of some neuropathological syndromes, including migraine, although experimental verification has not been possible up to now. Taking into account that the retina is a true part of the CNS, our data may be interpreted as the requested verification.

Animals↗