Topic
Retina circulation
About: Retina circulation is a research topic. Over the lifetime, 49 publications have been published within this topic receiving 2601 citations.
Papers
TL;DR: Using OCT angiography, reduced peripapillary retinal perfusion in glaucomatous eyes can be visualized as focal defects and quantified as perIPapillary flow index and peripAPillary vessel density, with high repeatability and reproducibility.
Abstract: Importance Vascular factors may have important roles in the pathophysiology of glaucoma. A practical method for the clinical evaluation of ocular perfusion is needed to improve glaucoma management. Objective To detect peripapillary retinal perfusion in glaucomatous eyes compared with normal eyes using optical coherence tomography (OCT) angiography. Design, Setting, and Participants Prospective observational study performed from July 24, 2013, to April 17, 2014. Participants were recruited and tested at Casey Eye Institute, Oregon Health & Science University. In total, 12 glaucomatous eyes and 12 age-matched normal eyes were analyzed. The optic disc region was imaged twice using a 3 × 3-mm scan by a 70-kHz, 840-nm-wavelength spectral OCT system. The split-spectrum amplitude-decorrelation angiography algorithm was used. Peripapillary flow index was calculated as the mean decorrelation value in the peripapillary region, defined as a 700-µm-wide elliptical annulus around the disc. Peripapillary vessel density was the percentage area occupied by vessels. The data statistical analysis was performed from October 30, 2013, to May 30, 2014. Main Outcomes and Measures Variability was assessed by the coefficient of variation. The Mann-Whitney test was used to compare the 2 groups of eyes. Correlations between vascular and visual field variables were assessed by linear regression analysis. Results In 12 normal eyes, a dense microvascular network around the disc was visible on OCT angiography. In 12 glaucomatous eyes, this network was visibly attenuated globally and focally. In normal eyes, between-visit reproducibilities of peripapillary flow index and peripapillary vessel density were 4.3% and 2.7% of the coefficient of variation, respectively, while the population variabilities of peripapillary flow index and peripapillary vessel density were 8.2% and 3.0% of the coefficient of variation, respectively. Peripapillary flow index and peripapillary vessel density in glaucomatous eyes were lower than those in normal eyes ( P r = −0.808) and peripapillary vessel density (Pearson r = −0.835) were highly correlated with visual field pattern standard deviation in glaucomatous eyes ( P = .001 for both). The areas under the receiver operating characteristic curve for normal vs glaucomatous eyes were 0.892 for peripapillary flow index and 0.938 for peripapillary vessel density. Conclusions and Relevance Using OCT angiography, reduced peripapillary retinal perfusion in glaucomatous eyes can be visualized as focal defects and quantified as peripapillary flow index and peripapillary vessel density, with high repeatability and reproducibility. Quantitative OCT angiography may have value in future studies to determine its potential usefulness in glaucoma evaluation.
637 citations
TL;DR: Research on retinal oxygen (O2) distribution and use is reviewed, focusing on O2 microelectrode studies in animals with circulatory patterns similar to those of humans, offering the potential for O2 to be used therapeutically in retinal vascular occlusive diseases and retinal detachment.
Abstract: We reviewed research on retinal oxygen (O2) distribution and use, focusing on O2 microelectrode studies in animals with circulatory patterns similar to those of humans. The inner and outer halves of the retina are different domains in terms of O2. Understanding their properties can suggest mechanisms of and therapies for retinal diseases. Inner retinal PO2 averages about 20 mm Hg. Effective O2 autoregulation of the retinal circulation ensures that inner retinal PO2 is relatively uninfluenced by systemic hypoxia and hyperoxia and increased intraocular pressure in healthy animals. Failures of the retinal circulation lead to tissue hypoxia that underlies the vasoproliferation in diabetic retinopathy and retinopathy of prematurity. Choroidal blood flow is not regulated metabolically, so systemic hypoxia and elevated intraocular pressure lead to decreases in choroidal PO2 and photoreceptor O2 consumption. The same lack of regulation allows choroidal PO2 to increase dramatically during hyperoxia, offering the potential for O2 to be used therapeutically in retinal vascular occlusive diseases and retinal detachment.
559 citations
Journal Article•
TL;DR: The IOP at which this occurred, IOPmax, represents the highest IOP (lowest mean perfusion pressure P min) at which the retina is able to maintain normal blood flow, demonstrating that a decrease of 36% or less in perfusions pressure is adequately compensated by retinal vascular autoregulation.
Abstract: Autoregulation of the retinal circulation in response to an acute elevation of intraocular pressure was investigated in 17 subjects (23 eyes) with no ocular abnormalities, by means of the blue field entoptic phenomenon. This phenomenon allows a person to observe leukocytes flowing in his own macular capillaries. Subjects were instructed to compare the speed of their leukocytes in one eye with that in the other eye. All subjects perceived equal speed in both eyes. During their observation of the leukocytes, the intraocular pressure (IOP) was rapidly raised in one eye to a level at which autoregulation was not sufficient to maintain normal blood flow. At that level of IOP, subjects described the leukocytes moving slower in this eye than in the fellow eye. The IOP was then decreased in steps of 2 to 3 mm Hg until the subjects reported observing equal leukocyte speeds in both eyes. The IOP at which this occurred, IOPmax, represents the highest IOP (lowest mean perfusion pressure Pntin) at which the retina is able to maintain normal blood speed, and presumably normal blood flow, by autoregulation. In our normal subjects, the average IOPmax was 29.6 ± 2.0 mm Hg, corresponding to an average Pmin of 27 ± 6 mm Hg and demonstrating that a decrease of 36% or less in perfusion pressure is adequately compensated by retinal vascular autoregulation.
222 citations
TL;DR: The results indicate that the RBF may decrease in patients with type 2 diabetes with no or early-stage diabetic retinopathy and in those with mild Retinopathy.
Abstract: PURPOSE To evaluate the differences in retinal circulation in eyes of patients with type 2 diabetes with no or early-stage diabetic retinopathy compared with control eyes. METHODS Seventy-five nondiabetic eyes and 194 eyes with type 2 diabetes mellitus were evaluated. The type 2 diabetic eyes were classified into two groups: 139 eyes (139 patients) without diabetic retinopathy (NDR) and 55 eyes (55 patients) with mild nonproliferative diabetic retinopathy (NPDR). The retinal circulatory parameters were measured with laser Doppler velocimetry, and the factors that affect retinal hemodynamics were determined in a cross-sectional population of patients with type 2 diabetes. RESULTS The group-averaged blood velocity (V) and retinal blood flow (RBF) in the NDR and mild NPDR groups were significantly (P < 0.01) lower than in the non-DM group. The diameter and wall shear rate were also significantly (P < 0.05) lower in the NDR group than in the nondiabetic control eyes. Multiple regression analysis showed that the RBF was independently and negatively correlated with serum low-density lipoprotein and creatinine. HbA1c was significantly (P < 0.05) higher in participants in the lowest RBF quartile than in the highest quartiles. CONCLUSIONS The results indicate that the RBF may decrease in patients with type 2 diabetes without retinopathy and in those with mild retinopathy.
136 citations
Journal Article•
TL;DR: The rat retinal circulation shows a pronounced retinal response toET-1 intravitreal injection, and the blunted ET-1 response in diabetic rats is consistent with previously reported results, demonstrating resistance to ET- 1 action in retinal pericytes exposed to high glucose.
Abstract: Purpose The endothelins are potent vasoactive peptides. This study was performed to characterize the in vivo effects of the endothelin peptides on the retinal circulation in nondiabetic and diabetic rats. Methods The video fluorescein angiography methodology was used to quantitate retinal hemodynamic responses to endothelin-1 (ET-1) and endothelin-3 (ET-3) in rats. A total of 99 rats were used for these experiments. Video fluorescein angiography recordings were performed before and at different times after intravitreal injection of different concentrations of ET-1 and ET-3 in nondiabetic and diabetic rats. Vascular diameters and retinal circulation times were determined using computer-assisted image analysis of the recorded angiograms. Results The maximal response to ET-1 was observed at 15 minutes after intravitreal injection and was maintained for as long as 30 minutes after injection. Subsequent data measured at 15 minutes after intravitreal injection showed significant prolongation of retinal circulation times and retinal artery constriction. For example, at a concentration of 10(-7) M, the retinal circulation time increased by 270% +/- 121% of the baseline value. In contrast, 10(-7) M ET-3 injection showed a 52% +/- 29.5% increase in circulation time compared to baseline. In diabetic animals, 10(-7) M ET-1 injection showed a blunted response (only 26% +/- 8% of baseline) compared to the same ET-1 injected concentration in nondiabetic rats. Conclusions The rat retinal circulation shows a pronounced retinal response to ET-1 intravitreal injection. The response to ET-3 is significantly less than it is to ET-1, and in diabetic animals there was also a significant blunting of the retinal response to ET-1. The blunted response to ET-3 is consistent with the lower affinity of retinal vessel ET-1 receptors to ET-3. The blunted ET-1 response in diabetic rats is consistent with previously reported results, demonstrating resistance to ET-1 action in retinal pericytes exposed to high glucose.
105 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 1 |
| 2017 | 3 |
| 2016 | 5 |
| 2015 | 4 |
| 2013 | 2 |
| 2011 | 1 |