Changes In Ocular Blood Flow Research Articles

Longitudinal changes of ocular blood flow using laser speckle flowgraphy during normal pregnancy.

PurposeInnovative laser speckle flowgraphy (LSFG) enables noninvasive evaluation of retinal microcirculation and the usefulness has been reported in the field of ophthalmology. LSFG has allowed us to measure the real time changes of retinal blood flow without pupillary dilatations and contrast media. Herein, we investigated the change of retinal blood flow in normal pregnant women during gestation using LSFG.MethodsA prospective cohort study was conducted in 53 pregnant women who visited our institution between January, 2013 and July, 2014. Finally, a total of 41 participants without any obstetric complications were available for evaluation. Retinal blood flow was measured with LSFG in a total of 4 times during pregnancy (T1. 11–13 weeks, T2. 19–21 weeks, T3. 28–30 weeks, T4. 34–36 weeks) and mean blur rate (MBR), blowout score (BOS), flow acceleration index (FAI), and resistive index (RI) are analyzed from these measurements. Relations between LSFG parameters and mean arterial blood pressure (MAP) are determined throughout pregnancy.ResultsMBR showed no significant changes throughout pregnancy. BOS showed a tendency to increase in the 3rd trimester. FAI values showed a slight increase from the 1st to 2nd trimester while a significant decrease was noted in the 3rd trimester. RI exhibited no changes between the 1st and 2nd trimesters, values decreased significantly after the 3rd trimester. MAP was positively correlated with BOS, and negatively correlated with FAI and RI.ConclusionThe present study clearly demonstrated that profiles of LSFG parameters demonstrated a decrease of resistance in retinal blood vessels. These changes in indices provide a highly sensitive reflection of physiological changes in vascular resistance due to pregnancy. Thus, LSFG may be useful, as a non-invasive, diagnostic tool to detect pregnancy related disorders such as preeclampsia.

Retrobulbar ocular blood flow changes measured by colour Doppler imaging after intra-arterial chemotherapy in retinoblastoma

PurposeTo evaluate the effects of intra-arterial chemotherapy on retrobulbar blood flow parameters in patients with retinoblastoma.Methods20 eyes of 10 patients with unilateral retinoblastoma that were treated with intra-arterial chemotherapy were...

Changes in ocular blood flow measured by laser speckle flowgraphy and regional cerebral oxygen saturation during aortic arch surgery with selective cerebral perfusion

Changes in ocular blood flow measured by laser speckle flowgraphy and regional cerebral oxygen saturation during aortic arch surgery with selective cerebral perfusion

Characteristics of systemic and regional hemodynamics in ischemic retinal vein occlusion in young and middle-aged adults

Introduction and purpose. Retinal vein occlusion (RVO) accounts for 60 % of cases of all acute vascular ophthalmic events with a global prevalence of 0.2-2 %. Lately, the RVO prevalence in young adults steadily increases. Impair-ments of ocular hemodynamics are considered to be its leading risk factors, and ocular blood flow depends on systemic hemodynamic condition. To evaluate the relation between systemic hemodynamics and ocular blood flow in RVO in young and middle-aged adults. Methods. The study included 18 patients with RVO and 30 persons without ophthalmic pathological findings. In all patients, routine ophthalmic examination was performed, as well as an additional ocular blood flow assessment (ophthalmoplethysmography, ophthalmorheography, ophthalmosphygmography, and fluorescein angiography [FA]). 24-hour blood pressure (BP) monitoring was performed to estimate systemic hemodynamics. Results and discussion. Statistically significant differences (p 0.7 and r>0.2). FA showed zones of peripheral retinal ischemia with a mean area of 159.02 mm 2 . A relation between evaluated parameters and those of 24-hour BP monitoring was not found. However, non-dippers showed a tendency towards a lower hemodynamic parameters and increased choroidal thickness. Conclusions. In young and middle-aged patients, predominantly ischemic RVO occurs, with specific peripheral localization of retinal ischemia. In patients before the age of 50, one of the main risk factors for peripheral ischemic RVO is the ocular blood flow impairment. A positive correlation was established between the ocular blood flow and the pattern of choroidal thickness changes. It is suggested that most significant ocular blood flow changes are typical for non-dippers.

Recent Clinical Applications of Laser Speckle Flowgraphy in Eyes with Retinal Disease.

Retinal diseases related to ischemia, such as diabetic retinopathy, are the main cause of blindness worldwide. However, the pathogenesis of these diseases remains unclear, as does the time course of associated changes in ocular blood flow. Laser speckle flowgraphy (LSFG), which uses the laser speckle phenomenon to detect and quantify ocular circulation, is a promising candidate for a noninvasive method to measure ocular blood flow in living eyes. A recently developed LSFG measurement parameter, mean blur rate (MBR), can serve as a quantitative and reproducible index of retinal blood cell velocity. Mean blur rate can be used in the study of retinal diseases to evaluate microcirculation in the retinal vessels, choroid, and optic nerve head. In addition to overall MBR (MA), LSFG measurements of optic nerve head microcirculation can be divided into vessel-area MBR (MV) and tissue-area MBR (MT). Absolute values for MT have been shown to be linearly correlated with capillary blood flow, regardless of fundus pigmentation. Recently, there has been an increasing number of reports on the clinical applications of LSFG in retinal disease.

Doppler Optical Coherence Tomography ‐ A New Method For The Assessment Of Neurovascular Coupling In The Retina

SummaryIn recent years, we have shown that a dual‐beam bidirectional Doppler OCT system allows to measure total blood flow in the ocular fundus and can also be used to detect changes in this flow values due to various stimuli.Neurovascular coupling (NC) refers to a phenomenon where local blood flow is elevated with increased neuronal activity. NC may be essential to deliver increased amounts of oxygen, glucose and other nutrients to neurons when they are active. As such a breakdown in NC may contribute to cell death in neurodegenerative diseases.OCT ‐ due to its high resolution ‐ is superior to other methods used to measure physiological parameters in the human body. In a recent study, we measured total retinal blood flow in the human eye and assessed flow changes due to a stimulus with diffuse luminance flicker. We measured an increase of about 40%, which is assumed to occur as a consequence of an increased firing rate of retinal ganglion cells.Our results show that dual‐beam bidirectional DOCT may serve as a powerful tool to study changes in ocular blood flow due to changes in neuronal activity and, thus may contribute to the investigation of neurodegenerative diseases and the development of neuroprotective strategies.

Changes of ocular blood flow in patients with subclinical atherosclerosis

Changes of ocular blood flow in patients with subclinical atherosclerosis

Temporal retinal nerve fibre layer thinning in cluster headache patients detected by optical coherence tomography.

The exact pathophysiology of cluster headache (CH) is still not fully clarified. Various studies confirmed changes in ocular blood flow during CH attacks. Furthermore, vasoconstricting medication influences blood supply to the eye. We investigated the retina of CH patients for structural retinal alterations with optical coherence tomography (OCT), and how these changes correlate to headache characteristics, oxygen use and impaired visual function. Spectral domain OCT of 107 CH patients - 67 episodic, 35 chronic, five former chronic sufferers - were compared to OCT from 65 healthy individuals. Visual function tests with Sloan charts and a substantial ophthalmologic examination were engaged. Reduction of temporal and temporal-inferior retinal nerve fibre layer (RNFL) thickness was found in both eyes for CH patients with a predominant thinning on the headache side in the temporal-inferior area. Chronic CH patients revealed thinning of the macula compared to episodic suffers and healthy individuals. Bilateral thinning of temporal RNFL was also found in users of 100% oxygen compared to non-users and healthy controls. Visual function did not differ between patients and controls. Our OCT findings show a systemic effect causing temporal retinal thinning in both eyes of CH patients possibly due to attack-inherent or medication-induced frequent bilateral vessel diameter changes. The temporal retina with its thinly myelinated parvo-cellular axons and its more susceptible vessels for the vasoconstricting influence of oxygen inhalation seems to be predisposed for tissue damage-causing processes related to CH.

Short-term effects of intravitreal triamcinolone acetonide injection on ocular blood flow evaluated with color Doppler ultrasonography.

To evaluate the changes in ocular blood flow with color Doppler ultrasonography (CDU) after intravitreal triamcinolone acetonide (IVTA) injection. A total of 46 patients who underwent IVTA (4 mg/0.1 mL) injection for diabetic macular edema (DME) (n=22), central retinal vein occlusion (CRVO) (n=12) and choroidal neovascular membrane (CNVM) (n=12) were included in the study. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistivity index (RI) were measured from the ophthalmic artery (OA), the central retinal artery (CRA) and the posterior ciliary artery (PCA) of each patient with CDU before, at the end of the first week and at the end of the first month following IVTA injection. In the DME group, PSV of OA at the first of the first month (mean±SD) (37.48±10.87 cm/s) increased compared to pre-injection value (31.39±10.84 cm/s) (P=0.048). There was a statistically significant decrease (P=0.049) in PSV of CRA at the end of the first month (7.97±2.67 cm/s) compared to the pre-injection (9.47±3.37 cm/s). There was not any statistically significant difference on the other parameters in the DME group. Also, there was not any statistically significant difference on the ocular blood flow values in the CRVO and CNVM groups. We observed that 4 mg/0.1 mL IVTA increased PSV of OA and decreased PSV of CRA in DME patients and did not have any effect on ocular blood flow values of CRVO and CNVM patients.

Ocular Blood Flow Changes in Behçet Disease Patients with/without Thrombotic Disease

ABSTRACTIn this study, the authors aimed to evaluate ocular blood flow changes in Behçet disease (BD) with and without thrombotic disease. Ninety eyes of 90 patients with a diagnosis of BD (30 eyes with active uveitis, 23 eyes with inactive uveitis, 25 eyes without ocular involvement, and 12 eyes without ocular involvement and with a history of thrombosis) and 30 eyes of 30 age- and sex-matched control patients without any systemic disease with a total of 120 eyes were evaluated. In all cases, ophthalmic, central retinal, and ciliary artery flow parameters were measured with colour Doppler ultrasonography (CDU). The ocular blood flow parameters of all vessels in patients with active uveitis were found to be affected. All the flow parameters in the CRAs of the study groups were significantly different from the control group (p < 0.001). Additionally, in non-ocular BD patients with thrombosis, blood flow parameters were affected more than the parameters in non-ocular BD patients without thrombosis and control patients. In conclusion, major haemodynamic changes were observed using CDU in the ophthalmic vessels of ocular Behçet patients. Also, CDU may detect ocular blood flow alterations before initial ocular clinical manifestations appear in BD patients

Pulsatile ocular blood flow changes after panretinal photocoagulation treatment in patients with proliferative diabetic retinopathy

To prospectively assess the effects of panretinal photocoagulation (PRP) treatment on pulsatile ocular blood flow (POBF) in patients with proliferative diabetic retinopathy (PDRP). The study included 40 eyes with PDRP in 27 patients. The PRP treatments were completed in 3 sessions with 3-week intervals. The intraocular pressure (IOP), pulse amplitude (PA), pulse volume (PV), and POBF changes that arose during the sessions were recorded using a blood flow analyzer. The average age of the patients was 57.37 ± 11.14 years. The pre-PRP basal IOP, PA, PV, and POBF values were 20.44 ± 4.13 mmHg, 4.23 ± 1.73 mmHg, 6.89 ± 2.28 μL, and 21.86 ± 5.83 μL/s, respectively. One month after the completion of the PRP sessions, the values were 18.49 ± 4.44 mmHg, 2.78 ± 1.13 mmHg, 5.27 ± 2.08 μL, and 15.89 ± 5.05 μL/s, respectively, and the differences were significant (P = 0.001, P < 0.0001, P < 0.0001, and P < 0.0001, respectively). PRP treatment reduces the choroidal blood flow and consequently causes significant decreases in IOP, PA, PV, and POBE .

Pseudoexfoliation syndrome and cardiovascular diseases.

Pseudoexfoliation (PEX) syndrome is a well-recognized late-onset disease caused by a generalized fibrillopathy. It is linked to a broad spectrum of ocular complications including glaucoma and perioperative problems during cataract surgery. Apart from the long-known intraocular manifestations, PEX deposits have been found in a variety of extraocular locations and they appear to represent a systemic process associated with increased cardiovascular and cerebrovascular morbidity. However, as published results are inconsistent, the clinical significance of the extraocular PEX deposits remains controversial. Identification of PEX deposits in the heart and the vessel wall, epidemiologic studies, as well as, similarities in pathogenetic mechanisms have led to the hypothesis of a possible relation between fibrillar material and cardiovascular disease. Recent studies suggest that PEX syndrome is frequently linked to impaired heart and blood vessels function. Systemic and ocular blood flow changes, altered parasympathetic vascular control and baroreflex sensitivity, increased vascular resistance and decreased blood flow velocity, arterial endothelial dysfunction, high levels of plasma homocysteine and arterial hypertension have all been demonstrated in PEX subjects. Common features in the pathogenesis of both atherosclerosis and PEX, like oxidative stress and inflammation and a possible higher frequency of abdominal aorta aneurysm in PEX patients, could imply that these grey-white deposits and cardiovascular disorders are related or reflect different manifestations of the same process.

Abstract 295: Sodium Restriction Increases Ophthalmic Artery Systolic Velocity in Healthy Subjects

Changes in ocular blood flow occur in systemic diseases. A high peak systolic velocity (PSV) in the ophthalmic artery (OA) has been observed in diabetes mellitus and hypertension, conditions often associated with high tissue renin-angiotensin system (RAS) activity and reduced renal plasma flow (RPF). Since our group has demonstrated that sodium restriction ( a high RAS state ) is associated with a decrease in RPF which is correctable with ACE inhibition, we hypothesized that sodium restriction would result in higher ophthalmic PSV. Sixteen healthy volunteers (age 46.2±13.2, male 69%, white 75%, BMI 26±3.7) were placed on a low sodium (LS) diet (10 mmol/day) for 1 week followed by high sodium (HS) diet (200 mmol/day). Sodium balance was assessed by 24hr urine collection. BP, RPF (PAH clearance) and OA hemodynamic measurements (Multigon, NY) were made after overnight fasting and rest in the supine position. Sodium restriction did not affect BP (systolic/diastolic LS: 121/73 ± 12/7 vs HS: 122/72 ± 15/9 mmHg, mean ± SD, NS) or heart rate (69 ± 16 vs 70 ± 15/min, NS). As expected, RPF was lower on LS compared with HS (599.2 ± 89.8 vs 633.4 ± 93.5ml/min/1.73 m 2 , p=0.006). Sodium restriction was associated with higher OA peak (38.8 ± 6.4 vs 33.2 ± 6.0 cm/sec, p=0.018) and mean (19.7±2.9 vs 17.1±3.5, p=0.003) systolic velocity ( Figure ). There was no change in end-diastolic velocity (10.6±2.5 vs 9.7±2.4, p=0.266) with sodium restriction. In conclusion, sodium restriction was associated with an increase in OA peak and mean systolic velocity in healthy individuals. Further studies are required to investigate the potential relevance of our results to diabetic and hypertensive retinopathy.

Ocular Pulse Amplitude is associated with ocular blood flow velocities in healthy subjects and patients with primary open angle glaucoma, but not normal tension glaucoma

AbstractPurpose Purpose: to determine the correlation between ocular blood flow changes throughout the cardiac cycle on ocular pulse amplitude (OPA) in glaucoma patients and healthy subjects.Methods Method: A prospective, case‐control study was designed with dynamic contour tonometry and color Doppler Imaging performed in healthy controls and glaucoma patients. An offline waveform analysis of the Doppler signal was performed by a masked observer for each of the retrobulbar arteries. Linear regression models using intraocular pressure (IOP), age and Doppler waveform variables [(resistance index (RI) and systolic/diastolic velocity ratio (Sm/Dm)] were designed to identify independent variables associated with OPA.Results Results: 192 patients were included [healthy controls: 55; normal tension glaucoma (NTG): 63, primary open‐angle glaucoma (POAG): 74]. OPA showed a significant associated with the constructed model in healthy individuals and in POAG patients (r=0.54, p&lt;0.001; r=0.43, p&lt;0.001, respectively). Short ciliary arteries flow variables were the only vascular‐related parameters independently associated with OPA in these groups (p&lt;0.05). IOP was independently associated with OPA in the POAG group (p&lt;0.001), but not the healthy group (p=0.48). OPA in the NTG group did not correlate with the constructed model (r=0.24, p=0.21).Conclusion Conclusions: OPA seems to reflect blood flow changes in the short ciliary arteries in healthy individuals and POAG patients, but not in NTG patients. In the latter, the ocular pulse may relate to other variables than blood flow velocities.

Assessment of ocular hemodynamics after laser in situ keratomileusis using color Doppler imaging

To investigate ocular blood flow changes in healthy myopic patients following laser in situ keratomileusis (LASIK) using color Doppler imaging. Sixteen eyes of 16 myopic patients were studied. LASIK was performed and intraocular pressure was raised to levels ≥65 mmHg. Color Doppler images were obtained to study the ophthalmic and central retinal arteries preoperatively and postoperatively at 1 day, 1 week, and 1 month. There was no significant correlation between patient age and preoperative ocular blood flow parameters. A significant positive correlation between the degree of myopia and the peak systolic volume of the ophthalmic artery (r = 0.6, P = 0.01) was found. A highly significant decrease in the peak systolic volume and end-diastolic volume with an increase in the resistive index of both arteries (P < 0.005) was seen at 1 day and 1 week postoperatively. There was no significant difference between the preoperative and postoperative data 1 month after the procedure. The findings of this study show temporary alterations in ocular blood flow parameters after LASIK. LASIK is an increasingly common lifestyle procedure and further studies on larger groups are still recommended.

The influence of retrobulbar adipose tissue volume upon intraocular pressure in obesity

It is known that glaucoma is associated with elevated intraocular pressure and obesity, yet the precise etiology remains unclear. The aim of this study was to determine whether there is a potential causality between the volume of retrobulbar adipose tissue and the level of intraocular pressure in obese subjects compared with non-obese. A total of 100 subjects were divided according to the body mass index (BMI), into two groups: normal weight (n = 50, BMI = 18-24.9 kg/m2) and obese (n = 50, BMI > or = 30 kg/m2) subjects. Anthropometric measurements, body composition analysis, measurement of intraocular pressure, as well as magnetic resonance imaging (MRI) of the head at the level of the optic nerve, and the derived retrobulbar adipose tissue volume, were undertaken in all subjects. The obese subjects, as compared with normal weight ones, had a significantly higher mean retrobulbar adipose tissue volume (6.23 cm3 vs 4.85 cm3, p < 0.01) and intraocular pressure (15.96 mmHg vs 12.99 mmHg, p < 0.01). Furthermore, intraocular pressure correlated positively with retrobulbar adipose tissue volume. In obese people, elevated intraocular pressure may be caused by changes in ocular blood flow, affected by the physical pressure exerted by higher retrobulbar adiposity, and/or by internal vascular changes secondary to complications of obesity. These findings indicate the need for more frequent measurement of intraocular pressure in obese individuals to earlier detect glaucoma, and in so doing prevent irreversible blindness.

Ligation of the Pterygopalatine and External Carotid Arteries Induces Ischemic Damage in the Murine Retina

This study aimed to characterize the functional and morphologic changes in a murine model of ocular ischemic disease caused by vascular occlusion. Retinal ischemia was induced by unilateral ligation of the pterygopalatine artery (PPA) and the external carotid artery (ECA) in anesthetized mice. Changes in ocular blood flow and retinal circulation were evaluated by three different methods: laser speckle blood flow imaging, fundus imaging, and fluorescein isothiocyanate angiography. Five days after reperfusion following 3- or 5-hour ischemia, an electroretinogram (ERG) was recorded, and the retinal histology was examined and quantified. The effects of a free radical scavenger, edaravone, using the model were evaluated by ERG and histologic analysis. The ligation of both the PPA and the ECA significantly reduced ocular blood flow and narrowed the blood vessels. Five hours of ischemia reduced the a-wave, b-wave, and oscillatory potential amplitudes of the ERG. The number of cells in the ganglion cell layer and the thickness of both the inner plexiform layer and the inner nuclear layer were reduced in the ischemic group. Retinal ischemia caused an increase in terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells in the inner layer after 21-hour reperfusion following 3-hour ischemia and 19-hour reperfusion following 5-hour ischemia. Edaravone (1 mg/kg, administered intraperitoneally) significantly reduced the retinal ischemic damage. These findings indicate that the murine model in which both the PPA and the ECA are ligated may be useful to clarify the pathologic mechanisms of retinal ischemic diseases and to evaluate neuroprotective drugs that target retinal ischemic injury.

Retrobulbar Ocular Blood Flow Changes after Orbital Decompression in Graves' Ophthalmopathy Measured by Color Doppler Imaging

To evaluate if decompression surgery produces changes in retrobulbar blood flow parameters in Graves' ophthalmopathy (GO). Retrobulbar blood vessels of 26 eyes (14 patients) that underwent orbital bone decompression between June 2009 and May 2010 were measured prospectively using color Doppler ultrasound before and after surgery. The disease was inactive in all patients enrolled according to the European Group on Graves' Orbitopathy. Patients were classified with mild, moderate-to-severe, or sight-threatening disease. All patients underwent a full ophthalmic examination including intraocular pressure and Hertel measurement. An age-matched control group included 20 eyes of 20 healthy volunteers. The resistance indexes (RIs) in the central retinal artery (CRA) and ophthalmic artery (OA) were significantly higher in patients with GO preoperatively than in the control group (P < 0.001, P = 0.001 respectively). After decompression surgery, a significant decrease in RIs occurred in the CRA (5%) and OA (6%) (P = 0.002, P < 0.001 respectively). Proptosis was decreased a median of 6 mm (range, 4-7). Three-wall decompression surgery resulted in a significantly greater reduction in exophthalmos (median 7 mm) compared with two-wall surgery (median 5 mm) and one-wall surgery (2.5 mm). Although no significant correlation was found, the RIs decreased more with major reductions in exophthalmos. In inactive moderate-to-severe GO, the RIs of the CRA and OA are higher than in normal subjects. The authors hypothesized that increased RIs of inactive GO may be due to orbital extrinsic compression of vascular structures because decompression surgery leads to decreases in the RIs of both the CRA and OA.

Le flux sanguin oculaire dans le glaucome

In clinical practice, the vascular factor seems to be essential in glaucoma. Nevertheless, the various studies investigating the relations between the changes in ocular blood flow and risk of glaucoma often have diverse and contradictory conclusions. The variety of the methods in studies on ocular blood flow, the absence of a reference examination, and the absence of large clinical studies probably explain the problems bringing to light an indisputable relation. However, it remains essential, in any glaucoma, to look for and treat the vascular risk factor and most particularly to decrease intraocular pressure, the treatment that currently remains the most reliable to improve ocular blood flow.

An investigation of changes in ocular blood flow in rabbits with long-term hyperhomocysteinemia using color doppler ultrasonography

Hyperhomocysteinemia was induced in rabbits using methionine. Ocular blood flow changes were examined by color Doppler ultrasonography (CDU). Materials and methods: Fifty New Zealand rabbits were divided into 5 groups. Groups 1-4 received one of the following chemicals: methionine only, methionine plus vitamin B6, methionine plus vitamin B12, or methionine plus folic acid. Controls received no chemicals. Serum homocysteine levels were measured on treatment days 1 and 60. Orbital vessels were examined by CDU on day 60. Results: In the 4 study groups, homocysteine levels were significantly elevated on day 60 compared to the levels on day 1 (P < 0.05). Elevations of homocysteine levels in group 1 were greater than those of groups 2 and 4 on day 60 (P < 0.05). When results of ocular blood flow changes were compared, no statistically significant difference was found based on flow velocities in the ophthalmic artery. Measurements from the ciliary artery revealed a statistically significant decrease in flow velocity in the study groups (P < 0.05). Conclusion: Using CDU, we found that flow velocities in the ciliary artery were decreased. This condition is attributed to atherosclerotic and thromboembolic alterations of the ocular vessels due to hyperhomocysteinemia.