Blood Flow Velocity In Ophthalmic Artery Research Articles

Effect of PCI on ophthalmic artery hemodynamics in patients with acute coronary syndrome.

We aimed to explore the effects of percutaneous coronary intervention (PCI) on the ophthalmic artery (OA) hemodynamics in patients with acute coronary syndrome (ACS). A total of 73 participants (Group0: healthy controls, Group1: Patients with ACS underwent PCI < 3 months, Group2: Patients with ACS underwent PCI ≥ 3 months) were enrolled. Computed tomographic angiography images were used to construct three-dimensional models of participants' OAs. Numerical simulations based on computational fluid dynamics were used to acquire hemodynamic parameters. The angle between the OA and internal carotid artery in Group2 was significantly larger compared with Group0 and Group1 (P = 0.003 and P = 0.044). Hemodynamic simulation showed a significantly slower OA blood velocity in Group1 than in the control (P < 0.001) and Group2 (P = 0.033). Lower wall shear stress was found in Group1 than that in control (P = 0.040). Patients after PCI had a higher wall pressure than healthy controls (P = 0.012 and P = 0.004). Mass flow ratios were decreased in Group1 and Group2 (P = 0.021 and P = 0.002). The hemodynamic parameters of OA were correlated with several clinical indicators. The OA blood flow velocity of patients with ACS after PCI initially slowed down, which increased the risk of plaque formation, and then showed an increasing trend. There was a correlation between OA hemodynamic parameters and clinical indexes related to cardiac stress. Ischemia-reperfusion injury and changes in blood flow status after PCI may affect OA morphology and hemodynamics, leading to ocular lesions. ChiCTR2100050428.

Effect of Blood Pressure Reduction on Intraocular Pressure and Ophthalmic Artery Blood Flow Velocity in Hypertension.

Purpose: To evaluate the effect of reducing blood pressure (BP) by atenolol and amlodipine on (1) intraocular pressure (IOP) and (2) ophthalmic artery blood flow (OAF) velocity in new hypertensives. Methods: A prospective, observational cohort study conducted at a tertiary care center in India after IRB approval. New hypertensives treated with atenolol 25 mg or amlodipine 5 mg were divided into 2 groups of 30 patients each. BP, IOP by Goldmann applanation tonometry and OAF velocity by transcranial doppler sonography was performed before medication and post medication on day 1, 7, and 30. Results: There was a significant decrease in IOP with both drugs; the effect was greater with atenolol. Atenolol: premedication IOP - 16.06 ± 2.13 mmHg and day 30-12.46 ± 1.94 (22.4%) [P < 0.001], amlodipine: premedication IOP-15.13 ± 2.55 mmHg and day 30- 13.06 ± 2.14 (13.68%) [P < 0.001]. A decrease of 0.5 mmHg in IOP with every 10 mmHg (95% CI: 0.121-0.826, P value = 0.01) decrease in systolic BP was noted after oral atenolol. The OAF peak systolic velocity and mean flow velocity were equally reduced with both drugs (P < 0.001). The end-diastolic velocity, reduced only with atenolol (P = 0.049) but returned to baseline with amlodipine at 1 month. Conclusions: BP reduction by atenolol and amlodipine led to decreases in IOP and OAF velocity, greater with atenolol. The IOP decrease was likely due to reduced blood flow. A slight decrease in the diastolic flow of the ophthalmic artery was noted with atenolol.

A Study of Maternal Ophthalmic Artery Doppler Indices in Diabetics and Smokers

The aims of this study are to characterize the ophthalmic artery (OA) perfusion in smoker pregnant ladies, diabetic pregnant ladies and smoker diabetic pregnant ladies using Doppler indices and to compare with normal healthy pregnancy. The sample was divided into 4 groups: group 1 were normal healthy pregnant ladies (N=57) , group 2 were smokers pregnant ladies (N=44) ,group 3 were diabetic pregnant ladies (N=64),and group 4 were diabetic smoke pregnant ladies (N=71) ladies. All groups were examined and assessed during the pregnancy period for OA Doppler indices of both right and left eyes. The resistive index (RI), pulsatility index (PI), and mean velocity (MV) were determined. Comparisons were performed between the norms and the other three groups. Result showed significant increasing in RI,PI in the right and left eyes in all groups at p≤0.000 except in smoker pregnant ladies p≤ 0.069 , the PI decreased in the third trimester,as well the MV decreased significantly with advancing GA. A significant differences were detected between norms and the three groups at p≤0.000 In conclusion, Doppler velocimetry is an acknowledged technique for evaluation of the RI, PI, and MV in the OA. Regarding the results smoking provokes perfusion changes in ophthalmic artery in smoker pregnant ladies. Thus, there are signs of an OA vasoconstriction and hypoperfusion . OA blood flow velocity was decreased in diabetic pregnant ladies.

Baseline retrobulbar blood flow is associated with both functional and structural glaucomatous progression after 4 years.

Previous studies suggest that vascular abnormalities are involved in the pathogenesis of open-angle glaucoma. This study aims to examine the relationship of baseline retrobulbar blood flow measurements with functional and structural glaucomatous progression in patients with open-angle glaucoma over 4 years. In this study, 112 patients with open-angle glaucoma were examined at baseline and 78 with retrobulbar blood flow assessments were followed to 4 years. Colour Doppler imaging was used to evaluate retrobulbar blood flow. Structural disease progression was examined with optical coherence tomography and Heidelberg Retinal Tomography III. Functional disease progression was monitored with automated perimetry using Humphrey visual fields. Mixed-model analysis of covariance was used to test for significance of changes from baseline to 4-year follow-up. Two-sample t tests and χ2 tests were used to test for baseline blood flow differences between patients who progressed and those who did not progress. Patients who progressed structurally had a statistically significant lower baseline mean ophthalmic artery peak systolic velocity (PSV) (p=0.024) and ophthalmic artery end diastolic velocity (EDV) (p=0.012) compared with those who did not progress. Similarly, a lower baseline mean ophthalmic artery PSV (p=0.031) and ophthalmic artery EDV (p=0.005) were associated with patients who progressed functionally compared with those who did not progress after 4 years. In this study population, lower baseline ophthalmic artery blood flow velocities were associated with simultaneous structural and functional glaucoma progression after 4 years.

Neuroretinal rim area and ocular haemodynamic parameters in patients with normal-tension glaucoma with differing intracranial pressures

PurposeTo assess the differences in the neuroretinal rim area (NRA) and ocular haemodynamic parameters in patients with normal-tension glaucoma (NTG) with differing intracranial pressure (ICP) values.Methods40 patients (11 males) with...

Agreement among three examiners of colour Doppler imaging retrobulbar blood flow velocity measurements

To assess the agreement among three masked examiners on central retinal artery (CRA) and ophthalmic artery (OA) blood flow velocity measurements performed with colour Doppler imaging (CDI) in healthy volunteers. The study included 30 eyes of 15 healthy volunteers. Prior to the study, all examiners underwent intensive CDI training by an expert to facilitate uniformity in performing measurements according to a specific protocol. Following the eligibility visit, three masked examiners performed CDI measurements assessing the CRA and OA in both eyes of all subjects. All CDI images were analysed by a masked grader. Intraclass correlation coefficients (ICC) were calculated for peak systolic velocity (PSV) and end diastolic velocity (EDV) in the CRA and OA among the examiners. p-values < 0.05 were considered statistically significant. The study included seven men and eight women (mean age 30.9 ± 4.5 years). In right eyes, ICCs for PSV and EDV in the CRA ranged from 0.917 to 0.961 and from 0.937 to 0.980, respectively. ICCs for PSV and EDV in the OA ranged from 0.802 to 0.926 and from 0.611 to 0.891, respectively. In left eyes, all ICCs for PSV and EDV were >0.9, both in the CRA and the OA. All p-values calculated for ICCs were statistically significant. Expert training and execution of a specific protocol for CDI of ocular blood flow velocity measurements provide highly reproducible results in healthy volunteers. This is important for long-term studies assessing ocular hemodynamics, where multiple examiners may be involved.

Cold stimulation induces different responses of ophthalmic artery blood flow velocity depending on baseline blood pressure and gender

Earlier, we have introduced the spectral index (SI), which was derived from the harmonic content of the blood flow velocity envelope of the ophthalmic artery. SI changed in dependency on the baseline blood pressure (bBP). We now examined SI during sympathetic activation by cold stimulation for 300 s in dependency on bBP to investigate the response to sympathetic neural activity in arterial hypertension. Ten men and 12 women with normal bBP (age, 60.5+/-4.6 years and 61.9+/-7.2 years) and age-adjusted men and women with increased bBP underwent the cold pressor test, including a periodical measurement of blood pressure and blood flow velocity in the ophthalmic artery, the latter by pulsed Doppler sonography. From this, the course of the SI was calculated. During cold stimulation men with increased bBP achieved their SI peak and their systolic blood pressure peak earlier than those with normal bBP (P=0.002 and P=0.035, respectively) and their SI slope was steeper than in normotensive men (P=0.002). Multiple testing showed that the difference of SI decrease between men with normal and increased bBP occurs on average 60 s after the beginning of cold stimulation (P=0.018). These differences were not found between female blood pressure groups, but the results in women may be influenced by antihypertensive treatment of some of the hypertensive women. In conclusion, the SI is useful to evaluate the response to sympathetic activation in hypertensive men but a larger study population should confirm the study results in women.

Root-MUSIC analysis of nitric oxide-mediated changes in ophthalmic artery blood flow velocity waveforms

Clinical and experimental studies indicate that structural and functional changes in the microvasculature can predate or accompany risk factors for cardiovascular disease at the earliest stages in the disease process. In the current work, both simulated and actual Doppler ultrasound maximum blood velocity waveform envelopes recorded from the ophthalmic artery were analysed using a root-MUSIC and least squares fitting approach to determine amplitude frequency spectra. Both amplitude and frequency components of noise contaminated simulated waveforms were reliably determined indicating the robustness of the technique. The technique was then used to compare the spectral content of the ophthalmic artery blood velocity waveforms of normal controls in three test states: at baseline, following administration of GTN, a nitric oxide donor, and following administration of L-Name, a nitric oxide inhibitor. Principal components derived from root-MUSIC analysis discriminated between waveforms in baseline and non-baseline test states ( p < 0.00001) and between GTN and non-GTN test states ( p = 0.0002).

Colour Doppler imaging evaluation of blood flow parameters in the ophthalmic artery in acute and chronic phases of optic neuritis in multiple sclerosis

Optic neuritis (ON) is a common manifestation of multiple sclerosis (MS). It is caused by the immune-mediated inflammation of the optic nerve. Some vascular factors that may influence blood flow in the ophthalmic artery (OA) have also been suggested as factors in the pathogenesis of ON. The purpose of our study was to evaluate blood flow velocities and resistance (RI) and pulsatile (PI) indices in the OA in both orbits in patients in the acute and chronic phases of unilateral ON and to compare these with equivalent findings in healthy control subjects. Orbital colour Doppler imaging (CDI) was performed in 40 consecutive MS patients during acute unilateral ON prior to corticosteroid treatment. Optic neuritis was diagnosed on the basis of clinical presentation and facultative assessment of visual evoked potentials (VEPs). The peak systolic (PSV) and end-diastolic (EDV) velocities and RI and PI were measured in the OA in both eyes. We compared results from affected and unaffected orbits using the paired t-test. The same measurements were performed in 114 MS patients with a history of acute unilateral ON that occurred > 1 year prior to ultrasound examination. We also measured the same parameters in the middle cerebral arteries (MCAs) on both sides in all subjects in both groups. The same measurements were obtained in healthy controls. The PSV (p < 0.0001), RI (p < 0.0001) and PI (p < 0.0001) in the OA in the eye affected with acute ON were significantly higher than in the unaffected eye. There was no difference in EDV in the OA between affected and unaffected eyes (p > 0.05) in the group with acute ON. We did not observe any significant differences between eyes in either blood flow velocities or the RI or PI (p > 0.05) in the group in the chronic phase of ON or in the control group. All the parameters in the MCAs on both sides were normal in both the acute and chronic groups, as well as in the control group. Pathophysiological changes during acute unilateral ON influence orbital haemodynamics, as is indicated by increased PSV, RI and PI in the OA in eyes affected with ON. However, these changes do not persist over longer periods.

Response to Analysis of Carotid and Ophthalmic Flow Velocity Waveforms

To the Editor: The authors are indebted to O’Rourke and Hirata1 for their valuable comment to our publication “Fourier Analysis of the Envelope of the Ophthalmic Artery Blood Flow Velocity: Age- and Blood Pressure–Related Impact”.2 We bewail if the impression should have occurred that only local vessel properties have been considered …

RETINAL DETACHMENT AND PROLIFERATIVE VITREORETINOPATHY

To analyze if endothelin-1 (ET-1) may have an effect on ophthalmic artery (OA) blood flow velocities and intraocular pressure (IOP) in retinal detachment (RD). Using radioimmunoassay, immunoreactive (IR) ET-1 levels were tested in both plasma and subretinal fluid (SRF) specimens from patients with RD, while only plasma specimens from normal (healthy) subjects were tested. OA Doppler sonography parameters and IOP were measured in eyes with RD, with and without proliferative vitreoretinopathy (PVR), their respective healthy fellow eyes, and normal eyes. RD eyes had lower OA peak systolic velocity (PSV) and end diastolic velocity (EDV), higher resistivity index (RI), lower IOP, and higher plasma IR ET-1 levels than normal eyes (P < 0.0001). Eyes with PVR had lower OA PSV and EDV, higher RI, lower IOP, higher plasma IR ET-1 levels, and higher SRF IR ET-1 than eyes without PVR (P < 0.0001). A statistically significant linear correlation was found among OA parameters, IOP, and SRF IR ET-1 measurements. Decreased OA blood flow velocities may explain lower IOP found in RD patients, and ET-1 levels may be responsible for both measurements.

Fourier Analysis of the Envelope of the Ophthalmic Artery Blood Flow Velocity

The harmonic content of the envelope waveform of the blood flow velocity in the ophthalmic artery was analyzed in aging and arterial hypertension. The case-control study enrolled 98 healthy men (age: 44.0+/-15.6 years), 100 healthy women (age: 44.5+/-19.1 years), which is group 1, and overall 199 hypertensive patients with increased systolic and diastolic blood pressure (in millimeters of mercury) before registration of the blood flow velocity using pulsed Doppler sonography. Group 2 was sufficiently treated (<or=140/<or=90), group 3 (>140/<or=90) and group 5 (>140/>90) were insufficiently treated, and group 4 (>140/<or=90) and group 6 (>140/>90) were untreated. Cronbach-alpha reliability of the calculated spectral coefficient and SI (SI) was 0.88 and 0.93, respectively. In control subjects, the SI was influenced by age (men: 45.1%; women: 50.2%; P<0.001 each) and in women additionally by mean arterial pressure (13.1%; P<0.001). The SI differed in subjects >43 years of age (men: 0.37+/-0.11; women: 0.26+/-0.08; P<0.001 each) as compared with subjects <or=43 years of age (men: 0.60+/-0.18; women: 0.48+/-0.13). All of these changes were lacking for the resistance index. In both men and women with hypertension, the SI decreases, whereas the mean arterial pressure increases, but the resistance index did not change. The SI of the ophthalmic artery allows an assessment of the ocular circulation in consideration of age and arterial blood pressure in contrast to the resistance index.

Expression of the PDE5 enzyme on human retinal tissue: new aspects of PDE5 inhibitors ocular side effects

We tested the effect of two phosphodiesterase type-5 (PDE5) inhibitors, sildenafil and tadalafil, on ophthalmic artery (OA) blood flow velocity and investigated the presence of the PDE5 enzyme on human retinal tissue in comparison with the PDE6 enzyme localization. Using Colour Doppler ultrasonography (CDU) we investigated, in 30 healthy young subjects (27.8 years of age; range, 24.3-33.7 years), the effects of a single oral dose of sildenafil (100 mg), tadalafil (20 mg), and placebo on OA blood flow velocity. Western blot for PDE6 and PDE5 protein expression was performed on frozen samples of human retina, testis, sperm, skin, and corpus cavernosum. Immunohistochemistry was performed on two ocular globes from dead donors. CDU showed a relationship between the administration of PDE5 inhibitors and OA blood flow velocity modifications in a time-dependent manner. Western blot and immunohistochemical analysis showed PDE6 and PDE5 presence in human retinal tissue and gave a map of its distribution. We demonstrated that (a) tadalafil and sildenafil are able to modify the OA flux in a time-dependent manner; (b) the PDE5 enzyme is expressed on retinal and choroid vasculature (smooth muscle and endothelial cells), on ganglion and bipolar cells; (c) human retinal tissues express the PDE6 enzyme in the rod and cone photoreceptors; (d) visual side effects after PDE5 inhibitors administration may be linked to a specific effect on the PDE5 enzyme; and (e) the PDE5 enzyme may have a physiologic role on ganglion and bipolar cells that need to be further investigated.

Sympathetic Activities Influence Blood-Flow Velocity and Resistance in the Rabbit Ophthalmic Artery

The aim of this study was to investigate sympathetic influences on blood-flow velocity and resistance in the rabbit ophthalmic artery during the transition period from the light to the dark phase. Eight (8) New Zealand albino rabbits were entrained to a daily 12-h light and 12-h dark cycle. Blood-flow velocities in the ophthalmic artery were determined at -2 (baseline), 0, 2, and 4 h after the onset of darkness. Pulsed and color Doppler images of the ophthalmic artery were recorded using a 12-MHz linear ultrasound transducer. Resistive index of blood flow was calculated using the peak systolic velocity and the end diastolic velocity. Measurements of intraocular pressure (IOP) were taken, using a pneumatonometer at the same time points. Blood-flow velocity, resistive index, and IOP were also determined in the same rabbits after surgical decentralization of the ocular sympathetic nerves. Compared with the baseline at -2 h, a significant increase in the resistive index of blood flow in the ophthalmic artery occurred at 2 and 4 h after the onset of darkness. Parallel elevations of IOP were observed. After the sympathetic decentralization, peak systolic and end diastolic velocities decreased and resistive indexes increased from the presurgical values in the ophthalmic artery. In the postsurgical rabbits, elevation of IOP was absent during the light-dark transition period. There was also no time-dependent increase of resistive index in the ophthalmic artery. During the light-dark transition period, resistance to blood flow in the rabbit ophthalmic artery increases in parallel to IOP elevation. The removal of sympathetic activities decreases blood-flow velocity, but increases blood-flow resistance. Like the endogenous elevation of IOP, the time-dependent increase of resistance to blood flow in the rabbit ophthalmic artery during the light-dark transition period depends upon, at least partially, ocular sympathetic activities.

Nitric oxide modulation of ophthalmic artery blood flow velocity waveform morphology in healthy volunteers

Quantitative analysis of the arterial pressure pulse waveform recorded by applanation tonometry of the radial artery can track NO (nitric oxide)-mediated modulation of arterial smooth muscle tone. The changes in pressure pulse waveform morphology result from pulse wave reflection arising predominantly from smaller arteries and arterioles. Employing Doppler ultrasound to record the spectral flow velocity waveform in the ophthalmic artery, we studied the effects of NO modulation on waveforms recorded in the proximity of the terminal ocular microcirculatory bed. In healthy young men (n=10; age 18-26 years), recordings were made at baseline, following 300 mug of sublingual GTN (glyceryl trinitrate) and during the intravenous infusion of 0.25 and 0.5 mg/kg of L-NAME (N(G)-nitro-L-arginine methyl ester). Peaks (P1, P2 and P3) and nodes (N1, N2 and N3) on the arterial flow velocity waveform were identified during the cardiac cycle and employed to quantify wave shape change in response to the haemodynamic actions of the pharmacological interventions. The administration of GTN resulted in a significant (P<0.05) increase in heart rate without significant alteration in blood pressure. At the doses employed, L-NAME did not significantly alter systemic haemodynamics. With the exception of peak Doppler systolic velocity, all other peaks and nodes decreased significantly in response to GTN (P<0.05 for all points compared with baseline). In response to the administration of L-NAME, all peaks and nodes decreased significantly (P<0.05 for all points compared with baseline). The resistive index, a ratio calculated from the peak and trough flow velocities employed to assess change in flow resistance, increased significantly in response to GTN (0.77 at baseline compared with 0.85; P<0.05). Quantification of changes in the flow velocity spectral waveform during the cardiac cycle sensitively identified NO modulation of smooth muscle tone prior to alteration in systemic haemodynamics. Focusing on the resistive index, which identifies isolated points on the waveform describing the excursions of flow, may provide misleading information in relation to the haemodynamic effects of drug interventions.

Effects of pars plana vitrectomy on retrobulbar haemodynamics in diabetic retinopathy

The purpose of the present study was to determine the effects of pars plana vitrectomy on retrobulbar haemodynamics in patients with proliferative diabetic retinopathy (PDR). Colour Doppler imaging was used for measurement of blood flow velocities and resistive index of the ophthalmic artery (OA), posterior ciliary arteries (PCA) and central retinal artery (CRA) in 14 eyes of 14 patients with PDR before pars plana vitrectomy and at the 1 and 6 months after operation. The patients were also treated by laser photocoagulation before or during surgery. Twenty age- and sex-matched healthy subjects were used as control group. Mean peak systolic velocity and the end diastolic velocity of the CRA in the patients with PDR were lower and the mean resistive index was higher than in those of the control group (P < 0.05). The mean end diastolic velocity of OA in the patients was lower and the mean resistive index was higher than in the control group (P < 0.05). The peak systolic velocity of the OA and the end diastolic velocity of the CRA were significantly increased (P = 0.043 and P = 0.018, respectively) and the mean resistive index of the CRA was significantly decreased after pars plana vitrectomy (P = 0.043). No significant changes were detected among preoperative and postoperative values of peak systolic velocity, end diastolic velocity, and resistive index of the PCA and the mean velocity of the central retinal vein (P > 0.05). The blood flow velocities of OA and CRA are decreased but the resistive index is increased significantly in patients with PDR. Pars plana vitrectomy in patients with PDR may decrease resistive index and improve blood flow in the CRA.

Ophthalmic artery blood flow velocity increases during hypocapnia

The effects of anesthetic management on blood flow to the optic nerve have not been well-studied. The ophthalmic artery provides the majority of the blood supply to the optic nerve via several smaller branches. Retinal blood flow has been shown to react to carbon dioxide (CO(2)) similar to intracranial vessels, but insufficient data exist for the ophthalmic artery. The purpose of this study is to examine the CO(2)-reactivity of the ophthalmic artery. Eight healthy awake subjects aged 28 to 50 yr were tested for CO(2)-reactivity in the ophthalmic artery using transcranial Doppler (TCD) insonation of blood flow velocity (V(op)), while simultaneously recording the V(op) of the middle cerebral artery (V(mca)) as an internal control. V(op) and V(mca) recordings were made under hypocapnic, normocapnic and hypercapnic conditions. The CO(2)-reactivity slope of V(mca) was 3.27% per mmHg PaCO(2). From normocapnia to hypercapnia, V(op) did not change significantly (mean +/- SD, 18 +/- 4 cm*sec(-1) to 18 +/- 6 cm*sec(-1)), (end-tidal CO(2), etCO(2), = 43 +/- 5 mmHg to 53 +/- 4 mmHg, respectively). In contrast, V(op) increased significantly under hypocapnic conditions (etCO(2) = 26 +/- 4 mmHg) to 25 +/- 5 cm*sec(-1) (P < 0.05). The CO(2)-reactivity slope of V(op) from normocapnia to hypocapnia was 2.57% per mmHg. This study demonstrates that V(op) increases with hypocapnia, but is unaffected by hypercapnia. The anastomoses of the ophthalmic artery with the external carotid artery, which displays a relatively fixed resistance, may account for these findings.

Normal neonatal values of ophthalmic and central retinal artery blood flow velocities.

To define standard values of blood flow velocities and indices in the ophthalmic and central retinal arteries in the neonatal period. Forty-two healthy full-term neonates comprised the study population. A color Doppler with mechanical sector probe was used for measuring blood flow velocity in the ophthalmic and central retinal arteries. Systolic, end diastolic, and mean-enveloped velocities were measured, and the resistance index and pulsatility index were calculated. Ophthalmic artery Doppler velocities were similar on the first and third days of life, but increased significantly on the fifth and seventh days of life; resistance index significantly increased during the first week of life, whereas pulsatility index did not change significantly. Doppler velocities of the central retinal artery were similar on the first and third days; they show a delayed increase compared to the ophthalmic artery. Central retinal artery blood flow velocities increased significantly from the third to seventh postnatal day. Resistance index also increased between the first two days and on the fifth and seventh postnatal days, while pulsatility index did not change. These data constitute a starting point for studying the possible relationship between eye circulation and pathogenesis of retinopathy of prematurity.

Ophthalmic artery blood flow velocity changes in diabetic patients as a manifestation of macroangiopathy.

The hemodynamic characteristics of ophthalmic artery (OA) blood flow velocity in diabetic patients with ocular involvement were evaluated. Changes in OA blood flow of eyes with background diabetic retinopathy (BDR), proliferative retinopathy (PDR) and ocular ischemic syndrome (OIS) were analyzed by Color Doppler imaging. Patients with BDR and PDR had significantly lower diastolic and mean blood flow velocities and higher pulsatility indices compared to controls. Diabetic patients with OIS had significantly lower systolic, diastolic and mean anterograde OA blood flow velocities than the controls. Pulsatility indices were higher in anterograde OA blood flow measurements compared to controls. Systolic blood flow velocities in rubeotic eyes with OIS were significantly lower than in rubeotic eyes with PDR. OA blood flow measurements by color doppler imaging may detect macroangiopathies in diabetic patients as manifested by carotid atheromas and arterio- and atherosclerosis of the OA and its branches.

Effects of scleral buckling on the retrobulbar haemodynamic changes.

This study was planned to investigate blood flow changes due to scleral buckling surgery. In addition the effects on these changes of factors related to patient characteristics and operative technique were studied. Central retinal artery (CRA) and ophthalmic artery (OA) blood flow velocities were studied with colour Doppler ultrasonography after scleral buckling surgery in 25 patients with unilateral rhegmatogenous retinal detachment. The effects of the patient's age, referral time, aetiological factors, operative technique, cryotherapy width and buckling distance on the haemodynamic changes were noted. Buckling surgery reduces the blood flow velocities in the CRA, but affects OA blood flow less. Encircling is found to be responsible and it is greater in patients with anatomical success. Other factors do not have any significant effect on these changes. Good anatomical and functional results can be achieved despite these haemodynamic changes. It must be kept in mind that these changes may cause complications in some patients and the surgery must be minimized.