Blood Flow In Glaucoma Patients Research Articles

Evaluation of Retinal Blood Flow in Glaucoma Patients Pre and Post Treatment using OCT angiography

Purpose: To evaluate retinal blood flow changes in glaucoma after intraocular pressure (IOP) lowering and to determine whether a correlation exists with retinal capillaries blood flow with IOP changes using optical coherence tomography angiography (OCTA)
 Materials and Methods: OCTA images were collected from 24 glaucomatous eyes for the macula and 21 eyes for the optic disc in a prospective, cross-sectional observational study. Microvascular changes were analysed at two retinal layers: deep vascular plexus (DVP) and the superficial vascular plexus (SVP) as well as choriocapillaries (CC), were compared pre and six weeks post intraocular pressure (IOP) lowering treatment.
 Results: Retinal blood flow across the macula showed no statistical significance at: SVP (z-score = -0.887), DVP (z-score = -1.093) and CC (z-score = -1.423). Further, no statistically significant difference in retinal blood flow was observed across the disc: SVP (z-score = -0.918), DVP (z-score = -1.057) and CC (z-score = -0.295). While the IOP showed improvement (z-score = -5.049), visual acuity deteriorated (z-score= 1.686)
 Conclusion: No statistical difference was found in the data for all layers of both the areas surrounding the disc and macula at 6 weeks. OCTA can detect microstructural defects and future longitudinal studies may provide further insight into effects of IOP lowering treatment on retinal blood flow in glaucoma patients in longer term.

Comparison of Neurovascular Coupling between Normal Tension Glaucoma Patients and Healthy Individuals with Laser Speckle Flowgraphy

ABSTRACT Background: The purpose of this pilot study was to investigate the differences in neurovascular coupling between Caucasian patients with normal tension glaucoma (NTG) and healthy subjects (HS) with laser speckle flowgraphy (LSFG). Methods: Measurement of optic nerve head blood flow was performed with LSFG. The mean blur rate of the whole optic nerve head (MA), of the big retinal vessels (MV) and of the microvasculature (MT) was analysed during continuous flicker light stimulation for four minutes. Results: We included 12 eyes from 12 Caucasian patients with a diagnosis of normal tension glaucoma and 12 eyes from 12 age- and sex-matched healthy individuals. MA, MV and MT all increased significantly in both groups during the observation period with no difference between the groups. Conclusion: Neurovascular coupling is detectable in NTG patients. Flicker light stimulation leads to a comparable increase in ocular blood flow in glaucoma patients and healthy individuals.

Choroidal blood flow in glaucoma patients in conditions of ophthalmic hypertension and compensated intraocular pressure

Purpose. To evaluate changes in chorioretinal blood flow in the early postoperative period after non-penetrating deep sclerectomy (NPDS) in patients with primary open-angle glaucoma (POAG) and determine their relationship with the level of Goldman intraocular pressure (IOPg). Material and methods. The study included 36 patients with primary open-angle glaucoma of stage 1–2, with an IOP level above 21 mm Hg at the maximum hypotensive mode. All patients underwent glaucoma surgery (NPDS) by a single surgeon. IOP measurement was performed by dynamic bidirectional applanation using the Ocular Response Analyzer (Reichert Inc., USA). When evaluating the results, the Goldman IOP indicators (IOPg) were taken into account. The ophthalmic examination included optical coherence tomography of the optic disk and macular area, as well as assessment of the blood flow of these structures using optical coherence tomography in angio mode (OCTA) (RTVue XR Avanti, Optovue Inc., США). The thickness of the choroid was estimated using crossline protocols performed through the center of the fovea in the horizontal and vertical meridians. Results. Based on the assessment of changes in the indicators of ocular blood flow in the postoperative period, all patients were divided into 2 groups: group 1 – 28 patients (28 eyes) who showed improvement in OCTA after surgery, group 2 – 8 patients (8 eyes) who, according to OCTA data, showed no changes or decreased indicators of ocular blood flow after surgery. In patients of both groups, the level of IOPg before surgical treatment was comparable. On the 3rd day after NPDS IOPg in the group 1 decreased to 9.3 ± 1.2 mm Hg, while in group 2 hypotonia was detected (IOPg 3,6 ± 1,3 mm Hg, р = 0,001). All patients showed an increase in the thickness of the choroid in the central area and peripapillary after glaucoma surgery: in group 1 by 23 and 26 %, in group 2 by 48 and 62 %, respectively. In group 2 there was a significant increase in the large vessels caliber and the vascular membrane thickness as a whole to 115.4 % of the original. In group 1 patients, against the background of normalization of ophthalmotonus, there was a tendency to increase the capillary density of the superficial vascular plexus (from 40.9 ± 5.38 to 41.1 ± 3.56 %) and the deep vascular plexus (from 43.9 ± 6.1 to 44.7 ± 5.97 %). There was a positive trend of increasing capillary density in the radial peripapillary plexus (from 46.6 ± 8.9 to 47.2 ± 9.0 %). In patients of group 2, capillary density significantly decreased: from 39.9 ± 3.64 to 37.6 ± 2.48 % in the superficial vascular plexus and from 41.1 ± 4.72 to 38.7 ± 3.51 % in the deep vascular plexus. Conclusion. A decrease in the level of ophthalmotonus after NPDS was accompanied, in most cases, by a moderate increase in the thickness of the choroid and a tendency to improve blood flow in the retinal plexuses. Postoperative hypotension is characterized by dysregulation of choroidal blood flow, decompression violation of topographic relationships, which generally leads to the formation of choroidal effusion and vascular detachment.

A vascular comparison between primary open‐angle glaucoma and normal‐tension glaucoma

PurposeTo contrast systemic and ocular vascular parameters in patients with normal‐tension glaucoma (NTG) versus primary open‐angle glaucoma (POAG).MethodsSub‐analysis of a prospective, cross‐sectional, case–control hospital‐based study investigating ocular blood flow in glaucoma patients (Leuven Eye Study). Systemic and ocular vascular parameters, including a questionnaire, blood pressure, dynamic contour tonometry, colour Doppler imaging, retinal oximetry and optical coherent tomography enhanced‐depth imaging, were compared between an age‐matched group of POAG and NTG patients.ResultsWe included 192 NTG and 214 POAG patients. Patients with NTG presented with significantly lower diastolic blood pressure (p = 0.01), decreased acceleration in the central retinal artery (p = 0.02), increased resistive index in the ophthalmic artery and central retinal vein (both p = 0.04), thinner peripapillary choroidal thickness (p < 0.001) and higher retinal venous oxygen saturation (p < 0.001). The odds of suffering from hypotension, migraine and Raynaud were significantly higher for NTG patients [95% confidence interval (CI) 1.30–8.73, 1.13–4.42 and 1.36–3.95 respectively], as were the odds of taking systemic bèta‐blockers, calcium antagonists and angiotensin II receptors blockers (95% CI 1.04–2.67, 1.21–6.62 and 1.18–5.97 respectively).ConclusionsPatients with NTG differ significantly on several ocular and systemic vascular parameters from POAG patients. These findings add further support to a higher weight for vascular‐driven neuropathy in NTG vascular etiology in NTG.

Decreased magnesium level and membrane potential of glaucoma patients

Background<br />One of the most important sight-threatening eye disorders in ophthalmology is glaucoma. Together with age related macular degeneration it is the most common cause of irreversible blindness. Magnesium (Mg) is considered to improve the ocular blood flow in glaucoma patients and could protect the retinal ganglion cell against oxidative stress. Membrane potential refers to the difference in electrical potential between the intracellular and the extracellular of a biological cell. The objective of this study was to determine the Mg serum level and membrane potential in glucoma subjects.<br /><br />Methods<br />A case-control study was conducted in eighty confirmed glaucoma patients and eighty normal subjects between 50 to75 years were selected. The serum sodium, potassium and calcium were estimated using Randox Kit. While membrane potential was determined by calculation using Nerst Equation. Magnesium levels were determined by atomic absorption spectrophotometer technique. An independent t-test was used to analyze the data. <br /><br />Results<br />The results obtained showed that the level of Magnesium serum (1.11 ± 0.14 mg/dL) and membrane potential (176.40 ± 42.00 J) was significantly decreased in glaucoma as compared to the controls (2.4 ± 0.68 mg/dL) and (251.76 ± 191.99) (p<0.05). The serum sodium, potassium and calcium were also significantly decreased among glaucoma subjects compared to control (p<0.005).<br /><br />Conclusion<br />The result probably suggests, that decrease in magnesium aggravates glaucoma while decrease in membrane potential could cause poor energy transmission and hence affect ocular blood flow. Hence, decreased magnesium and membrane potential levels contributes greatly to glaucoma.

Update and critical appraisal of combined timolol and carbonic anhydrase inhibitors and the effect on ocular blood flow in glaucoma patients

Topical hypotensive therapy with both timolol and carbonic anhydrase inhibitors has been shown to be efficacious at reducing intraocular pressure. Many prospective studies have also suggested that carbonic anhydrase inhibitors augment ocular blood flow and vascular regulation independent of their hypotensive effects. Although consistent in their findings, these studies must be cautiously interpreted due to the limitations of study design and specific blood flow imaging modalities. The purpose of this review is to appraise and critically evaluate the current body of literature investigating the effects of combined treatment with topical carbonic anhydrase inhibitors and timolol in patients with glaucoma with respect to ocular blood flow, visual function, and optic nerve head structure.

Short-term variability of systemic blood pressure and submacular choroidal blood flow in eyes of patients with primary open-angle glaucoma

To analyse short-term variability of systemic blood pressure and choroidal blood flow in glaucoma patients, and compare them with ocular hypertensive patients and controls. Thirty untreated patients with primary open-angle glaucoma (POAG), 25 untreated patients with ocular hypertension (OHT) and 50 healthy controls without local therapy were included in the study. Continuous 5-minute measurements of arterial systemic blood pressure (SBP) by Finometer and choroidal blood flow (CBF) by laser Doppler flowmetry were obtained. Variability of SBP and CBF was analysed by means of coefficient of variation and analyzed in ANOVA model. Linear regression analysis was performed on parameters of morphological (nerve fiber layer thickness) and functional glaucomatous damage (visual field) on one side, and between SBP and CBF on the other side. ANOVA model demonstrated significant differences in variability between the groups (p = 0.003); post-hoc analysis specified a significantly higher short-term variability of both the blood pressure and choroidal blood flow in POAG patients (coefficients of variation: 3.33% +/- 1.05% and 3.90% +/- 2.17% respectively) than in healthy controls (coefficient of variation: 2.57% +/- 0.80% and 2.94% +/- 1.52% respectively). No significant differences were found for OHT patients. POAG patients without local therapy demonstrate an increased short-term BP and CBF variability.

Influencing ocular blood flow in glaucoma patients: the cardiovascular system and healthy lifestyle choices

The cardiovascular system and lifestyle choices play important roles in influencing ocular blood flow regulation in patients with glaucoma. This includes the presence of vascular risk factors, abnormal autoregulatory responses, tissue oxygenation, and mitochondrial oxidative stress. Based on this comprehensive review, novel therapeutic approaches may be considered in selected patients for preventing and (or) delaying the progression of glaucoma.

Hornhautdicke und retrobulbärer Blutfluss bei Glaukompatienten

A correlation between a thin cornea and the presence of vascular risk factors has recently been reported in normal-tension glaucoma patients. The present study intended to investigate the correlation between central corneal thickness and basal retrobulbar blood flow in glaucoma patients. Corneal pachymetry and colour Doppler imaging (CDI) of the retrobulbar arteries (ophthalmic, central retinal and cilliary) were performed in 63 glaucoma patients. Linear mixed effect models were used to evaluate the association of central corneal thickness and retrobulbar blood flow. There was no significant correlation between central corneal thickness and blood flow in any of the assessed arteries (p = 0.13-0.88). A statistical relationship between central corneal thickness and retrobulbar blood flow could not be found in the examined sample of glaucoma patients.

Influencing ocular blood flow in glaucoma patients: the cardiovascular system and healthy lifestyle choices

<h2>Abstract</h2> The cardiovascular system and lifestyle choices play important roles in influencing ocular blood flow regulation in patients with glaucoma. This includes the presence of vascular risk factors, abnormal autoregulatory responses, tissue oxygenation, and mitochondrial oxidative stress. Based on this comprehensive review, novel therapeutic approaches may be considered in selected patients for preventing and (or) delaying the progression of glaucoma.

Evaluation of optic nerve head and peripapillary retinal blood flow in glaucoma patients, ocular hypertensives, and normal subjects

Purpose To compare optic nerve head (ONH) and peripapillary retinal blood flow in subjects with open-angle glaucoma (OAG), ocular hypertension (OHT), and normal eyes (NOR) using full-field perfusion analysis of scanning laser Doppler flowmetry (SLDF) images. Design Prospective, nonrandomized clinical trial. Methods Twenty uncontrolled OAG patients, 20 uncontrolled OHT patients, and 20 normal volunteers were prospectively enrolled. Mean ONH and peripapillary retinal blood flow measurements were performed by SLDF version 3.3 using five Heidelberg Retina Flowmeter (Heidelberg Engineering, Heidelberg, Germany) images. Statistical evaluations were performed on the three study groups using one-way analysis of variance. Flow values of the neuroretinal rim of the ONH, nasal peripapillary retina, and temporal peripapillary retina were then correlated with the clinical parameters of age, cup/disk (C/D) ratio, intraocular pressure (IOP), visual field mean defect, maximum-recorded IOP, and ocular perfusion pressure. Results Neuroretinal rim blood flow in the OAG group was 158 ± 79 arbitrary units (au), whereas in the OHT group it was 277 ± 158 au, and in the NOR group it was 272 ± 93 au. Differences were statistically significant between the OAG group and each of the other groups ( P = .001) but not between OHT and NOR groups ( P = .91). Peripapillary retinal flow values showed no statistically significant differences between groups ( P = .76 nasal and 0.93 temporal). Neuroretinal rim flow values showed a significant inverse correlation with C/D ratio ( P = .001). Mean neuroretinal rim blood flow was significantly higher (350 ± 184 au) in the 10 OHT patients with C/D ratios < 0.4 when compared with the 10 OHT patients with larger C/D ratios (203 ± 79 au) ( P = .039). Conversely, peripapillary retinal blood flow showed no significant correlation with any clinical parameter. Conclusion Open-angle glaucoma patients had significantly lower blood flow in the ONH compared with OHT patients and normal volunteers. No significant differences in ONH blood flow were found between ocular hypertensives and normal volunteers. For peripapillary retinal blood flow, no significant difference was seen between any groups. Neuroretinal rim blood flow was significantly inversely correlated to increased C/D ratio. Ocular hypertensives with larger C/D ratios demonstrated significantly lower rim blood flow compared with those with smaller C/D ratios, suggesting that rim perfusion might be reduced in high-risk ocular hypertensives before the manifestation of visual field defects.

Retrobulbar blood flow in glaucoma patients with nocturnal over-dipping in systemic blood pressure

PURPOSE: To evaluate the relationship between the circadian blood pressure rhythm and the retrobulbar blood flow in glaucoma patients. DESIGN: Cross-sectional study. METHODS: Circadian blood pressure measurements and color Doppler imaging (CDI) in the ophthalmic artery as well as the central retinal artery of one randomly selected eye were obtained in 193 primary open-angle glaucoma patients. CDI parameters were compared by means of analysis of covariance between patients with a nocturnal decrease in mean systemic blood pressure (MBP) below 20% of the average daytime MBP (over-dippers), patients with a decrease between 10% to 20% (dippers), and patients with a decrease of less than 10% (nondippers), using age, intraocular pressure (IOP), and MBP during color Doppler measurement as covariates. RESULTS: An analysis of covariance disclosed, after correcting for age, IOP, and MBP during color Doppler imaging, a significantly lower EDV ( P = .0096) and a significantly higher RI ( P = .033) in the central artery of over-dipping glaucoma patients compared with nondippers or dippers. This effect seemed independent of the use of vasoactive drugs. CONCLUSIONS: Glaucoma patients with a marked drop in nocturnal systemic blood pressure seem to have altered retrobulbar blood flow parameters, suggesting that an abnormal systemic blood pressure profile may be the manifestation of some kind of systemic vascular dysregulation relevant for the ocular circulation.

Retinale Nervenfaser schichtdicke und peripapillärer Blutfluss bei Glaukompatienten und Gesunden

In progressive glaucoma there is increasing loss of retinal nerve fibers and therefore decreasing nerve fiber layer thickness. As measurements of capillary blood flow have been reported to depend on nerve fiber layer thickness, this could result in incorrectly high blood flow measurements in patients with advanced glaucoma. In 33 healthy controls and 59 glaucoma patients we measured retinal nerve fiber layer thickness by laser polarimetry and relative capillary blood flow by scanning laser doppler flowmetry three times on the nasal and temporal peripapillary retina. For statistical analysis a regression analysis was used. The correlation coefficients for volume, velocity, and flow with nerve fiber layer thickness at the same location were 0.02/-0.03/-0.02 in the temporal retina and -0.22/-0.07/-0.19 in the nasal retina (all correlations nonsignificant). No correlation was found between nerve fiber layer thickness and capillary blood flow. Measurement of capillary blood flow in glaucoma patients thus does not appear to be affected by decreasing nerve fiber layer thickness.

Glaucoma patients demonstrate faulty autoregulation of ocular blood flow during posture change

BACKGROUND/AIMSAutoregulation of blood flow during posture change is important to ensure consistent organ circulation. The purpose of this study was to compare the change in retrobulbar ocular blood flow in...

Optic nerve blood flow in glaucoma: effect of systemic hypertension

PURPOSE: To investigate optic nerve head blood flow in patients with glaucoma and to assess the effect of systemic hypertension. METHODS: This study included 24 eyes of 24 patients with primary open-angle glaucoma. Eleven of these patients had a history of systemic hypertension. Results in patients with glaucoma were compared with those of 13 eyes of 13 age-matched normal controls. Determinations of relative optic nerve head blood velocity, volume, and flow were obtained with laser Doppler flowmetry in the superotemporal and inferotemporal neuroretinal rim and also in the cup. Means of the velocity, volume, and flow of these three measurement sites were calculated for each subject. RESULTS: Mean overall optic nerve head blood flow was 29% lower in glaucoma patients than in normal controls ( t test, P < .001). This decrease in flow was mainly caused by a decrease of 23% in mean blood velocity ( P < .001). Mean flow in glaucoma patients without systemic hypertension was 26% lower than that of glaucoma patients with hypertension (Tukey honest significant difference test, P = .05). A significant direct correlation was observed between mean flow and mean blood pressure (R = 0.51, P < .02). CONCLUSIONS: Optic nerve blood flow is reduced in glaucoma patients. Glaucoma patients without systemic hypertension have lower optic nerve blood flow than those with hypertension. Our results raise concerns that treatment of systemic hypertension may further decrease optic nerve blood flow in glaucoma patients.