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At least 595 records · Page 33Linked to original sources
PubMed1995

Decreased retinal blood flow in retinitis pigmentosa.

OBJECTIVE: To determine alterations in retinal blood flow in retinitis pigmentosa (RP). DESIGN: Case-control study. SETTING: Ophthalmology department of a university-affiliated hospital in Elazig, Turkey. SUBJECTS: Ten patients (20 eyes) with typical RP and 22 age-matched volunteer subjects (22 eyes) with no history of ocular or systemic disease. MAIN OUTCOME MEASURES: Central retinal artery peak systolic and diastolic blood flow velocity (measured by means of colour Doppler imaging), resistance index and pulsatility index. RESULTS: The mean peak systolic and diastolic flow velocity values were significantly lower in the study group than in the control group (4.96 +/- 1.3 vs. 11.11 +/- 1.5 cm/s [p < 0.00001] and 2.15 +/- 0.4 vs. 3.40 +/- 0.9 cm/s [p < 0.0001] respectively). The mean resistance index value was significantly lower in the study group (0.55 +/- 0.05) than in the control group (0.71 +/- 0.06) (p < 0.0001), as was the mean pulsatility index value (0.94 +/- 0.18 vs. 1.45 +/- 0.36) (p < 0.00001). CONCLUSIONS: Decreased retinal blood flow is an important feature of RP.

Adult↗
PubMed1993

Silicone oil tamponade for retinal detachment and delayed treatment of retinal tears.

Four patients underwent a vitrectomy procedure for retinal detachment associated with anterior and posterior proliferative vitreoretinopathy (D-1 type). In each patient, an internal tamponade was achieved with 1000-centistoke silicone oil. Preretinal and/or subretinal hemorrhage that was difficult to remove during surgery, as well as remnants of subretinal fluid, prevented complete intraoperative treatment of the retinal tears or the retinotomy with endolaser photocoagulation. The silicone oil tamponade kept the retina flat until laser treatment was applied to the retinal tears several weeks later, when the retinal blood and subretinal fluid had reabsorbed. When circumstances make achieving intraoperative laser marks difficult, silicone oil tamponade appears to be superior to a long-lasting gas tamponade. It provides a more permanent tamponade than gas and excellent visualization of the fundus several weeks after surgery, at which time laser marks can be completed.

Adult↗
PubMed1995

[A comparison between scleral buckling procedure and vitrectomy for the management of uncomplicated retinal detachment caused by posterior retinal break].

We reviewed conventional scleral buckling and vitrectomy for uncomplicated rhegmatogenous retinal detachment due to posterior retina break. A comparison was made for a consecutive series of 21 cases undergoing scleral buckling procedure and 15 cases receiving vitrectomy as the initial surgery. As regards surgical complications, in the scleral buckling procedure there was inadvertent severance or compression of the vortex veins in 16 (77%) of the 21 cases and postoperative choroidal detachment in 9 (43%). In vitrectomy, there were no remarkable intraoperative complications, but it led to progressive nuclear cataract in 10 (67%) of the 15 cases during the postoperative period. Both procedures produced successful retinal attachment with comparable visual recovery. The results indicate that vitrectomy is a useful procedure for cases of uncomplicated retinal detachment caused by deeply located retinal break.

Adult↗
PubMed1995

Blood-retinal barrier breakdown in retinitis pigmentosa: light and electron microscopic immunolocalization.

Macular edema can contribute to visual loss in the retinitis pigmentosa (RP), but the sites and mechanism of blood-retinal barrier (BRB) breakdown leading to macular edema are not known. An understanding of the mechanisms involved could lead to the design of effective pharmacologic therapy to prevent or minimize macular edema in RP. To investigate this problem, immunohistochemical staining for albumin was performed on paraffin sections of 22 normal and 29 RP-affected eyes. Specimens were graded for extent of albumin extravasation in different regions of the retina, optic nerve head, ciliary body, and iris. Electron microscopic immunocytochemical staining for albumin was performed on an additional 6 normal and 9 RP-affected eyes. Two-thirds of the eyes from patients with RP and no other ocular disorders demonstrated extravascular albumin in the inner portion of the posterior retina. This was evident even in the absence of cystoid macular edema (CME), but eyes that had CME showed extensive BRB failure. In some cases, passage of albumin from the choroid to the retina was prevented even in the absence of the retinal pigment epithelium (RPE). Electron microscopic immunocytochemistry revealed that albumin permeated retinal vascular endothelial cells and RPE cells that showed degenerative changes in RP.

Adolescent↗
PubMed1976

Primary retinal degeneration: evidence of normal phagocytosis in the retinal pigment epithelium.

In rats with primary retinal degeneration, lens extraction combined with total retinal detachment provided a model for injection of a tracer of colloidal carbon into the subretinal space. Electron microscopy and acid phosphatase cytochemistry were subsequently used to analyze the ingestion of tracer by the retinal pigment epithelium. It was found that the attachment, ingestion, and digestion phases of the phagocytic process were apparently preserved. From this evidence it is suggested that there is no lack of phagocytic power in the retinal pigment epithelium of affected rat strains.

Acid Phosphatase↗
PubMed1985

[Incidence of lipid changes in rhegmatogenous retinal detachment, retinal vein occlusion and primary chronic glaucoma].

Several studies suggest that vascular factors may play a role in the pathogenesis of rhegmatogenous retinal detachment, retinal vein occlusion and primary chronic glaucoma. We explored the lipoprotein abnormalities in three groups of 45 patients suffering from each of these diseases compared to three control groups. We did not find significant abnormalities of cholesterol, cholesterol lipoproteins, nor Apolipoprotein B. The only significant abnormality was the presence of a higher rate of hypertriglyceridemia in the retinal vein occlusion and primary chronic glaucoma groups in comparison with their control group. In these two affections, hypertriglyceridemia should be systematically researched and treated.

Apolipoproteins B↗
PubMed1978

Studies on retinal blood flow. I. Estimation of human retinal blood flow by slit-lamp fluorophotometry.

This article describes a new direct method for estimation of human retinal blood flow by slit-lamp fluorophotometry. The apparatus consists fundamentally of a modified slit lamp with an eye piece containing two fiberoptic probes connected to a double photometric detection system. Both optic fibers are focused on a retinal arterial segment, and the passage of a fluorescein bolus is automatically registered, giving, after correction, the mean transit time. Fluorescein angiography allows the determination of the volume of the arterial segment under study. Values for superior temporal retinal blood flow in healthy individuals show a mean value of 4.2 +/- 0.5 microliter/min. Studies in anemic patients show an increase of approximately 52% in the retinal blood flow. The potential causes of error associated with this technique, apart from the slight increase in intraocular pressure induced by the contact lens used, do not appear to be significant.

Adolescent↗
PubMed1984

Experimental retinal detachment. V. Fluid movement through the retinal hole.

Unilateral chronic rhegmatogenous retinal detachments were produced in eight cynomolgus monkeys. Fellow eyes underwent total vitrectomy. Aqueous-plasma and vitreous-plasma ratios of fluorescein isothiocyanate-dextran (70,000 molecular weight) after intravenous administration were less than 0.004 in detached and fellow eyes. Intravitreal injection of fluorescein isothiocyanate-dextran in detached eyes passed into the subretinal space at a rate of 1.12 microL/min, where it was visibly sequestered for months. In fellow eyes, fluorescein isothiocyanate-dextran moved slowly from the vitreous cavity into the anterior chamber. The aqueous flow through the anterior chamber was lower in detached eyes. It is concluded that in eyes with rhegmatogenous retinal detachment, a flow of fluid exits from the posterior chamber, through the vitreous humor and retinal hole, into the subretinal space, and across the retinal pigment epithelium.

Animals↗
PubMed1992

Treatment with intravitreal steroid reduces blood-retinal barrier breakdown due to retinal photocoagulation.

The effect of corticosteroid treatment on blood-retinal barrier breakdown caused by argon-laser panretinal photocoagulation was evaluated in the rabbit eye. One day before photocoagulation, eyes were given either a sub-Tenon (20-mg) or intravitreal (2-mg) injection of triamcinolone acetonide. The severity of blood-retinal barrier breakdown was measured after photocoagulation using rapid sequential magnetic resonance imaging following intravenous administration of gadolinium diethylenetriaminepentaacetic acid. Leakage of gadolinium diethylenetriaminepentaacetic acid into the vitreous space was significantly lower in eyes that received intravitreal triamcinolone acetonide than in control eyes (P = .007); however, sub-Tenon triamcinolone acetonide produced no significant reduction in leakage (P = .65) compared with controls. Fluorescein angiography supported the magnetic resonance imaging findings. We conclude that retinal photocoagulation in the rabbit eye produces blood-retinal barrier breakdown that is partially amenable to corticosteroid treatment.

Animals↗
PubMed1996

Transthoracic echocardiographic findings in patients with acute retinal arterial obstruction. A retrospective review. Retinal Emboli of Cardiac Origin Group.

OBJECTIVE: To assess the importance of cardio-embolic (emboli of cardiac origin) risk stratification in the cardiac evaluation of patients with acute retinal arterial obstruction. DESIGN: A multicenter retrospective study of patients with acute retinal arterial obstruction who underwent transthoracic echocardiography. SETTINGS: Four North American hospital centers. PATIENTS: One hundred patients with acute retinal artery obstruction in whom transthoracic echocardiography was performed. MAIN OUTCOME MEASURE: Anticoagulation or cardiac surgery based on abnormalities detected on transthoracic echocardiography. Transesophageal echocardiographic results were not evaluated, as they were rarely performed in our centers. Thus, the outcome measure was determined solely by the results of transthoracic echocardiography. RESULTS: Patients were divided into high- and low-risk groups based on their history of cardioembolic risk factors or the presence of a cardiac murmur. Of 67 patients with no risk factors, 41 (61%) had normal echocardiographic study results and 26 (39%) had abnormalities detected, of whom only 1 (1.5%) received anticoagulation or cardiac surgery. The presence of 1 or more cardio-embolic risk factors increased the likelihood for anticoagulation or cardiac surgery 25 times (odds ratio = 25; 95% confidence interval = 3.04-217.02). Although this result is clinically and statistically significant, it is possible that abnormalities missed by transthoracic methods may have been detected by transesophageal technology. CONCLUSIONS: In patients with acute retinal arterial obstruction at low cardioembolic risk, transthoracic echocardiography resulted in anticoagulation or cardiac surgery in 1 (1.5%) of 67 patients. Routine transthoracic echocardiography without follow-up transesophageal echocardiography for patients identified as having abnormalities such as left ventricular hypertrophy or mitral annular calcification and who are at low cardioembolic risk rarely resulted in anticoagulation or cardiac surgery.

Acute Disease↗
PubMed1995

Retinal ganglion cells in normal hamsters and hamsters with novel retinal projections. I. Number, distribution, and size.

We examined the number, spatial distribution, and size of ganglion cells in the retinae of normal Syrian hamsters and hamsters with retinal projections to the auditory and somatosensory nuclei of the thalamus, induced by neonatal surgery. As revealed by retrograde filling with horseradish peroxidase, there are about 64,600 contralaterally projecting retinal ganglion cells (RGCs) and 1,700 ipsilaterally projecting RGCs in the retinae of normal adult hamsters. Contralaterally projecting RGCs are distributed throughout the retina and have two local density peaks located within a central streak of high RGC density that is oriented approximately along the nasal-temporal axis. RGC density falls above and below the central streak, with a steeper gradient towards the upper retina. Ipsilaterally projecting RGCs are diffusely distributed within a crescent at the inferotemporal retinal periphery and are most dense at the internal border of the crescent. The soma diameter of contralaterally projecting RGCs ranges from 6 to 25 microns; the diameter distribution is unimodal, with a peak in the 10-13 microns range and is skewed toward smaller values, with an elongated tail towards higher values. Contralaterally projecting RGCs tend to be smaller in regions of higher density. Ipsilaterally projecting RGCs tend to be larger than contralaterally projecting RGCs both globally and within the temporal crescent, and their size distributions tend to be less regular and less well related to local density. The retinae of neonatally operated hamsters with novel retinal projections to the auditory. and somatosensory systems contain about one-fourth the normal number of contralaterally projecting RGCs, whose relative density distribution is approximately normal despite the drastic reduction of absolute RGC density. The range and distribution of RGC soma diameters are similar in normal and neonatally operated hamsters, and, in operated as in normal hamsters, contralaterally projecting RGC somata tend to be smaller in regions of higher density. Our results in normal hamsters suggest a role for intraretinal mechanisms in the determination of RGC size. Our findings in neonatally operated hamsters suggest that, despite the reduced number of RGCs in these animals, the same types of RGCs are found in the retinae of normal and neonatally operated hamsters.

Animals↗
PubMed2002

Biocompatibility assessment of silicone oil and perfluorocarbon liquids used in retinal reattachment surgery in rat retinal cultures.

The effects of silicone oil and perfluorocarbon liquids used in retinal reattachment surgery were studied in vitro using rat retinal cultures seeded on microporous inserts. These inserts allow the cell layer to be in contact with the material to be tested on the apical side and with the nutrient medium on the basal side. The materials tested were silicone oil, the perfluorocarbons perfluorophenanthrene and perfluoroctane, and hydroxypropylmethylcellulose. Perfluorophenanthrene, the heaviest of the compounds, induced a very precocious detachment of the cell layer. All the other tested biomaterials were compatible with cell survival and did not alter the structural organization of the retinal cultures, as revealed by scanning electron microscopy. By immunocytochemical techniques we evaluated the cell composition and the differentiation state of each of the cultures. In both control and treated samples, neuronal cells were well preserved. The expression of microtubule-associated protein 2, a marker of differentiated neuronal cytoskeleton, was not affected. Amacrine neurons, immunolabeled for gamma-aminobutyric acid, still were detectable after treatment. Synapses, marked by immunoreactivity for synapthophysin, were equally preserved. Vimentin-positive glial cells did not show modifications. The apoptotic rate, as determined by the terminal transferase-mediated dUTP-biotin nick end-labeling assay, was similar in treated and control samples. The results confirm that the use of biomaterials with a specific gravity close to intraocular fluids is compatible with retinal cell survival and differentiation in vitro.

Animals↗
PubMed2004

Patterns of retinal light absorption related to retinitis pigmentosa mutants from in silico model structures of rhodopsin.

Changes induced by mutations in rhodopsin that are associated with the degenerative visual disease retinitis pigmentosa result in an altered pattern of light absorption according to quantum mechanical simulations and reference experimental works. Eleven single-point mutations associated with retinitis pigmentosa at and in the proximity to the retinal binding pocket of rhodopsin have been modeled in silico and their spectra calculated with the NDOL (Neglect of Differential Overlap accounting L azimuthal quantum number) a priori method. The altered pattern of absorption found would lead to cumulative consequences in energy dissipation with aging. Different energy balances in the case of mutants at the very molecular level, compared to native nonmutated rhodopsin, can cause permanent cellular stress and would play a role in the progression of the retine degenerative process. It could explain the worsening of the pathological condition mostly in adults and suggests the probable beneficial effects of using quenching drugs and protection devices against excess of light in the early stages of life for avoiding or reducing potential damage.

Absorption↗
PubMed1988

Immune responsiveness to retinal S-antigen and opsin in serpiginous choroiditis and other retinal diseases.

The immune responsiveness to bovine retinal S-antigen and opsin has been investigated in some retinal disorders by means of in vitro lymphocyte proliferation, leukocyte migration inhibition and enzyme linked immune sorbent assays (ELISA). Sensitisation to S-antigen was observed in serpiginous choroiditis, but not in acute posterior multifocal placoid pigment epitheliopathy (APMPPE) or retinitis pigmentosa. No significant immune responsiveness was detected to opsin in any of the three diseases. Elevated antibody titers to S-antigen were observed in some individual patients and healthy subjects. However, none of the patient groups exhibited an elevated antibody titer as compared to the control group. Although serpiginous choroiditis and APMPPE share some prominent clinical characteristics, the sensitisation in the former disease may perhaps be attributed to more severe and prolonged damage of the photoreceptor cells and blood-retina barrier. A combination of previous and present results suggests that in immunological investigations of retinitis pigmentosa patients it is more effective to use human than bovine S-antigen as test antigen because a species specific epitope seems to be involved.

Antibody Formation↗
PubMed1986

The use of retinal tacks in the repair of complicated retinal detachments.

Retinal tacks that can be easily placed and removed allow precise intraocular control of retinal fixation in the repair of complicated retinal detachments. We used this technique in 41 consecutive cases of complicated retinal detachment. In 37 cases follow-up was six months or more. We achieved reattachment of the posterior pole, including the macula, in 22 patients after six months or more of follow-up. Postoperative visual acuities were 1/200 or better in 15 patients and 5/200 or better in six.

Humans↗
PubMed1983

Localization of specific autoantibodies in the retinal photoreceptor cell layer in experimental retinal autoimmunity.

The presence and localization of autoantibodies was determined in strain 13 guinea pigs with experimental retinal autoimmunity (ERA) induced by immunization with rhodopsin and rod outer segments (ROS). Sera were obtained from rhodopsin-immunized and from ROS-immunized guinea pigs before, during, and after onset of clinical uveitis. Autoantibodies were detected by indirect immunofluorescent staining of autogenic retinas as well as normal guinea pig retinas. Sera from animals with clinical disease showed specific labeling of the photoreceptor cell layer of the retina. The rhodopsin autoantibody showed a more defined specificity than the ROS autoantibody staining, only the retinal photoreceptors and retinal pigment epithelium. Specific fluorescence was localized only in the retina, and not in any other ocular or nonocular tissues. Neither the rhodopsin nor the ROS antibodies stained the uvea. Sera from animals taken before the onset of clinical disease did not demonstrate the presence of retinal-binding autoantibodies. These findings suggest that photoreceptor-binding autoantibodies appear in the sera of animals immunized with rhodopsin and with ROS, but only in animals with clinical disease. However, these antibodies probably are not the primary cause of pathology, since previous passive transfer experiments (data not shown here) could not be achieved with anti-ROS or with anti-rhodopsin antibodies. These autoantibodies could occur secondarily as a response to the bovine antigens which cross-reacted with the autologous guinea pig antigens. Subsequently these antibodies could be of primary importance in further tissue alteration and destruction.

Animals↗
PubMed1996

Design of clinical trials for drug combinations: cytomegalovirus retinitis--foscarnet and ganciclovir. The CMV retinitis retreatment trial.

The Cytomegalovirus Retinitis Retreatment Trial was a multicenter clinical trial designed to evaluate three treatments for the treatment of relapsed CMV retinitis; (1) foscarnet; (2) 'high-dose' ganciclovir, and (3) combination foscarnet and ganciclovir. Two hundred seventy-nine patients were enrolled and randomly assigned to one of these three regimens. Patients were followed monthly for 6 months and every 3 months thereafter. Outcomes of interest included: (1) mortality; (2) retinitis progression; (3) change in retinal area affected by CMV; (4) loss of visual field; (5) loss of visual acuity; (6) quality of life; and (7) treatment side effects.

Acquired Immunodeficiency Syndrome↗