Retrobulbar blood flow velocity in systemic lupus erythematosus assessed by color Doppler imaging.

OBJECTIVE: To analyze the blood flow in retrobulbar vessels in systemic lupus erythematosus (SLE) by color Doppler imaging (CDI) and to investigate the associations between immunological markers, retinal abnormalities, disease activity, and vascular parameters. METHODS: We examined 30 patients with SLE who were aged 32.1 ± 11.6 years with a disease duration of 68.0 ± 55.6 months and 30 participants in a control group. The peak systolic velocity (PSV), end diastolic velocity (EDV), pulsatility index (PI), and resistive index (RI) of the ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary arteries (PCAs) were determined. Physical and ophthalmic examinations with assessments of immunological markers were performed. All parameters were compared between SLE patients and normal controls while the correlations among parameters were analyzed. RESULTS: In the SLE group, CDI confirmed blood flow abnormalities in the CRA and PCAs, with significantly lower blood flow velocities and increased RI and PI (p < 0.05). There was a significantly negative correlation between disease duration and EDV in the CRA, PCA, and OA (p = 0.0423, 0.0453, 0.0448). There was also a significant relationship between the SLE Disease Activity Index and the PI of the OA (p = 0.0367). The patients who had received biological agents (Rituximab) had lower EDV in the CRA and PCA (p = 0.0026, 0.028). SLE patients with kidney or CNS involvement had a significant increase in the PI in the OA (p = 0.0287). The PSV and EDV in the CRA were significantly related to creatinine (p = 0.0007 and 0.0418). We also noted a significant decreased EDV in the CRA and an increased RI in the OA among participants positive for anti-dsDNA antibodies (p = 0.0331 and 0.0228). CONCLUSIONS: Retrobulbar circulatory disturbances were detected in SLE patients by CDI. These findings seem likely to affect smaller vessels like the CRA and PCA. However, the presence of measurable changes in the OA is generally indicative of a coexistent nephropathy or central nervous system (CNS) vasculitis. Creatinine, the disease activity index, being positive for anti-dsDNA, and receiving biological agents were associated with measurable changes on the retrobulbar blood flow.

Ocular Ischemic Syndrome and Its Related Experimental Models.

Ocular ischemic syndrome (OIS) is one of the severe ocular disorders occurring from stenosis or occlusion of the carotid arteries. As the ophthalmic artery is derived from the branch of the carotid artery, stenosis or occlusion of the carotid arteries could induce chronic ocular hypoperfusion, finally leading to the development of OIS. To date, the pathophysiology of OIS is still not clearly unraveled. To better explore the pathophysiology of OIS, several experimental models have been developed in rats and mice. Surgical occlusion or stenosis of common carotid arteries or internal carotid arteries was conducted bilaterally or unilaterally for model development. In this regard, final ischemic outcomes in the eye varied depending on the surgical procedure, even though similar findings on ocular hypoperfusion could be observed. In the current review, we provide an overview of the pathophysiology of OIS from various experimental models, as well as several clinical cases. Moreover, we cover the status of current therapies for OIS along with promising preclinical treatments with recent advances. Our review will enable more comprehensive therapeutic approaches to prevent the development and/or progression of OIS.

[Changes in ocular hemodynamics in patients recovered from COVID-19]. / Oftal'mogemodinamicheskie narusheniya posle perenesennoi koronavirusnoi infektsii, vyzvannoi virusom SARS-CoV-2.

PURPOSE: To evaluate the severity of hemodynamic changes in the ocular vessels of patients recovered from COVID-19. MATERIAL AND METHODS: The study included 44 patients (88 eyes) aged 28-60 years, among them 24 (54.5%) women and 20 (45.4%) men, with SARS-CoV-2 infection confirmed by PCR no more than 2 months prior to enrollment and with no ophthalmological complaints within 2 months before the disease, as well as 20 healthy volunteers (40 eyes). At the time of the study all patients had a negative PCR result for SARS-CoV-2. The patients were divided into 2 groups. The first group comprised 24 patients who did not take any anticoagulants during the treatment. The second group consisted of 20 patients who received anticoagulants (Rivaroxaban (Xarelto)) at a dosage of 10 mg per day for 1-1.5 months. The maximum systolic (Vs), end-diastolic (Vd) blood flow velocity, as well as resistance index (RI) in the ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCA) were measured in all study patients with the ultrasound imaging system VOLUSON E8 Expert («Kretz¼, USA). Additionally, the flowmetry method was used to assess the volumetric ocular blood flow (VOBF) on Ocular Blood Flow Analyzer system («Paradigm Medical Industries, Inc.¼, USA). RESULTS: In the first group, a decrease in Vs and Vd was noted amid a significant increase of RI in CRA and SPCA, as well as an increase of RI in OA compared with the age-normal values (p<0.05). In the second group, a decrease in Vs and Vd was noted amid a significant increase of RI in CRA, as well as a decrease in Vs in SPCA and an increase of RI in OA relative to the age-normal values (p<0.05). A decrease in VOBF was noted in the first group in comparison to the second group and the age norm (p<0.05). CONCLUSION: Blood flow velocity parameters in the ocular vessels are reduced in patients recovered from COVID-19 compared to the age-normal values. There was a significant decrease in volumetric ocular blood flow parameters in COVID-19 patients who did not take any anticoagulants compared to the age-normal values. Anticoagulants intake has a positive impact on hemodynamic characteristics in the ocular vessels and volumetric ocular blood flow in patients with COVID-19.

Retrobulbar blood flow in rat eyes during acute elevation of intraocular pressure.

Most studies of the effect of acute elevation of intraocular pressure (IOP) on ocular blood-flow have utilized optical coherence tomography (OCT) to characterize retinal and choroidal flow and vascular density. This study investigates the effect of acute IOP elevation on blood flow velocity in the retrobulbar arteries and veins supplying and draining the eye, which, unlike the retinal and choroidal vasculature, are not directly compressed as IOP is increased. By cannulation of the anterior chamber of 20 Sprague-Dawley rats, we increased IOP in 10 mmHg steps from 10 to 60 mmHg and returned to 10 mmHg. After 1 min at each IOP (and 3 min after return to 10 mmHg), we acquired 18 MHz plane-wave ultrasound data at 3000 compound images/sec for 1.5 s. We produced color-flow Doppler images by digital signal processing of the ultrasound data, identified retrobulbar arteries and veins, generated spectrograms depicting flow velocity over the cardiac cycle and characterized changes of vascular density and perfusion in the orbit overall. Systolic, diastolic and mean velocities and resistive and pulsatile indices were determined from arterial spectrograms at each IOP level. Baseline mean arterial and mean venous velocities averaged 30.9 ±â€¯10.8 and 8.5 ±â€¯3.3 mm/s, respectively. Arterial velocity progressively decreased and resistance indices increased at and above an IOP of 30 mmHg. Mean arterial velocity at 60 mmHg dropped by 55% with respect to baseline, while venous velocity decreased by 20%. Arterial and venous velocities and resistance returned to near baseline after IOP was restored to 10 mmHg. Both vascular density and orbital perfusion decreased with IOP, but while perfusion returned to near normal when IOP returned to 10 mmHg, density remained reduced. Our findings are consistent with OCT-based studies showing reduced perfusion of the retina at levels comparable to retrobulbar arterial flow velocity change with increased IOP. The lesser effect on venous flow is possibly attributable to partial collapse of the venous lumen as volumetric venous outflow decreased at high IOP. The continued reduction in orbital vascular density 3 min after restoration of IOP to 10 mmHg might be attributable to persisting narrowing of capillaries, but this needs to be verified in future studies.

Contrast-enhanced plane-wave ultrasound imaging of the rat eye.

Preclinical imaging, especially of rodent models, plays a major role in experimental ophthalmology. Our aim was to determine if ultrasound can be used to visualize and measure flow dynamics in the retrobulbar vessels supplying and draining the eye and the potential of contrast microbubbles to provide image and measurement enhancement. To accomplish this, we used a 128-element, 18 MHz linear array ultrasound probe and performed plane-wave imaging of the eyes of Sprague Dawley rats. Compound images were acquired by emitting unfocused wavefronts at multiple angles and combining echo data from all angles to form individual B-scans. Multiple imaging sequences were utilized, compounding up to six angles, with imaging rate of up to 3000 compound B-scans per second and sequence durations from 1.5 to 180 s. Data were acquired before and after intravenous introduction of contrast microbubbles. We found the total power of the Doppler signal in the image plane to increase approximately 20 fold after injection of contrast, followed by an exponential decay to baseline in about 90 s, The best-fit time constant of the decay averaged 41 s. While major vessels and the retinal/choroidal complex were evident pre-contrast, they were dramatically enhanced with contrast present, with details such as choroidal arterioles seen only with contrast. Ocular arteriovenous transit time determined from comparative enhancement curves in arteries and veins was approximately 0.2 s. In conclusion, plane wave ultrasound, especially with enhancement by contrast microbubbles, offers a means for the study of ocular hemodynamics using the rat eye as a model.

The Force Required to Inject a Column of Filler Through Facial Arteries.

BACKGROUND: Injectable fillers have become an integral part of facial rejuvenation, but vascular occlusion is a dreaded complication of such injections. OBJECTIVE: To determine the force required by the fingertip onto the plunger of the syringe to cause retrograde migration. METHODS: In this cadaver study, twelve 2-cm arterial segments and 4 fillers were tested. Injection pressure required to force a column of filler for 1 cm was measured. Five oculoplastics specialists were subsequently recruited and asked to inject the filler at a typical injection pressure. RESULTS: The nonhyaluronic acid filler required significantly more pressure to cause propagation of the material compared with all other fillers (p < .01). None of the other fillers differed significantly from each other. Typical injection pressures generated by experienced injectors were significantly lower than that required to cause propagation of filler at the desired velocity and significantly lower than mean arterial pressure. Measured pressure required to cause filler propagation was well within the normal range of the finger strength that can be generated by humans. CONCLUSION: Typical injection pressures from fingertip to plunger are lower than required to cause propagation of filler intravascularly.

Optic nerve sonography and ophthalmic artery Doppler velocimetry in healthy pregnant women: an Australian cohort study.

PURPOSE: Maternal ocular sonography offers a window into cerebrovascular and intracranial pressure changes in pregnancy. This study aimed to determine the Doppler velocimetric variables of the ophthalmic artery, and the mean diameter of the optic nerve sheath (ONSD), in an Australian cohort of healthy pregnant women. METHODS: A prospective observational cohort study of healthy women with uncomplicated singleton pregnancies in the third trimester was undertaken in a tertiary maternity service. A single prenatal ultrasonographic examination was performed on all participants, with a postnatal examination performed on a subgroup with uncomplicated deliveries. RESULTS: Fifty women were examined at a mean gestation of 35 weeks. The mean ± SD Doppler variables in the ophthalmic artery were peak systolic velocity (PSV) 41.89 ± 13.13 cm/s, second peak velocity 20.63 ± 8.97 cm/s, end diastolic velocity 9.29 ± 5.13 cm/s, pulsatility index 1.97 ± 0.53, resistive index 0.78 ± 0.07, peak ratio (second peak velocity/PSV) 0.49 ± 0.12, while the mean ONSD was 4.34 ± 0.4 mm. None of these variables had a demonstrable relationship with gestation or mean arterial pressure (MAP), nor did the sheath diameter have a relationship with any of the Doppler variables. CONCLUSIONS: The ocular sonographic variables observed in this population are similar to those reported in other cohorts. No clear relationship could be identified in this cohort between ophthalmic artery Doppler variables and the ONSD, and between each of these variables and gestation or MAP.

Anatomic variation of the entrance of the optic canal into the orbit.

Purpose: To characterise variations in the location of the optic canal and its entry into the orbit in relation to the sphenoid sinus. Methods: In this observational study, patients with high-resolution computed tomography (CT) scans seen by 2 specialists (RG and DR) over a period of 12 years were reviewed for study entry. The primary outcome measure was characterisation of the optic canal route in relation to the sphenoid sinus and the location of its opening within the orbit. Three-dimensional reconstructions of the bony orbits were created using the Mimics imaging software. Optic canals were classified according to the location of their entry into the orbit. Type 1 was defined as a canalicular course along the lateral wall of the sphenoid sinus and entry into the orbit through the medial wall. Type 2 was defined as a canalicular course in the superior wall of the sphenoid sinus with entry into the orbit through the roof. The angle of entry of each nerve into the orbit was calculated. Results: One-hundred patients (52 females and 48 males) contributed 100 orbits to the study. Type 1 configuration was noted in 90 orbits, whereas Type 2 was noted in 10 orbits. The mean angle (SD) of entry of Type 1 optic nerves into the orbit was 61° (10.7), whereas the angle of entry of Type 2 nerves was 32.35° (6.8). The difference was significant (p < 0.01). Conclusions: This study demonstrates variability of the path and outlet of the optic canal and presents a relatively common (10%) configuration in which the optic canal travels in the roof of the sphenoid sinus rather than the expected position in the lateral wall.

Color Doppler imaging in thyroid eye disease and its correlation to disease activity.

Purpose: To evaluate alterations in orbital color Doppler imaging (CDI) parameters and their correlation to disease activity and severity in patients with thyroid eye disease (TED). Methods: Seventy-six orbits of 45 TED patients and 40 orbits of 40 normal controls were enrolled in this cross-sectional study. According to clinical activity score (CAS), patients were categorized to active (CAS ≥ 3) or inactive disease (CAS < 3). Patients were also classified as having mild, moderate or severe disease. Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) in ophthalmic artery and central retinal artery, and maximum and minimum velocity in superior ophthalmic vein and central retinal vein were determined in all subjects. Results: There was a significant difference in maximum velocity of superior ophthalmic vein and EDV and RI of ophthalmic artery between patients with TED and normal subjects. Superior ophthalmic vein maximum and minimum velocity and ophthalmic artery RI were significantly higher in patients with active disease than inactive cases. Disease severity did not affect the blood flow parameters independently. A cutoff point of 3.99 cm/s in superior ophthalmic vein maximum velocity yielded a sensitivity of 91.2% and specificity of 81.2% in detecting active disease. Conclusion: Retrobulbar blood flow is altered in TED and is related to disease activity. Superior ophthalmic vein maximum velocity could be helpful in differentiation of active and inactive cases.

Color Doppler imaging of orbital vasculature before and after orbital decompression in thyroid eye disease.

Purpose: To measure alterations in orbital blood flow parameters using color Doppler imaging (CDI) before and after orbital decompression in patients with moderate to severe thyroid eye disease (TED). Methods: Resistance index (RI) and maximum and minimum velocity of ophthalmic artery (OA), superior ophthalmic vein (SOV), and central retinal artery (CRA) of 24 eyes (14 patients) with TED were measured before and at least 3 months after cosmetic orbital decompression procedure (single or double walls) using CDI. Complete eye examination was performed to define the severity (EUGOGO classification) and activity (clinical activity score) of TED. Results: Median OA (p = 0.003) and CRA (p = 0.001) resistance indices were significantly reduced postoperatively. Significant differences were found in maximum (p = 0.001) and minimum (p = 0.014) velocity of SOV before and after surgery. While a significant decrease in exophthalmometry was observed after the orbital decompression (p = 0.031), intraocular pressure changes were not significant (p = 0.182). Conclusion: Orbital decompression procedure led to a significant reduction of RI in both CRA and OA in patients with TED.

Effect of intravitreal aflibercept (Eylea®) on retrobulbar hemodynamics in patients with neovascular age-related macular degeneration.

PURPOSE: To investigate the short-term effect of single intravitreal aflibercept injection on retrobulbar blood flow in patients with neovascular age-related macular degeneration (nAMD). METHODS: Twenty eyes of 20 patients with nAMD scheduled for single intravitreal aflibercept (Eylea®) injection and 20 fellow eyes (uninjected) were enrolled in this prospective interventional study. The hemodynamic parameters of the ophthalmic artery (OA), central retinal artery (CRA) and posterior ciliary artery (PCA) comprising peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) were measured by using color Doppler ultrasonography (CDU) in both injected and uninjected fellow eyes at baseline and 1 week after the injection. RESULTS: The measured first-week values of PSV and EDV in the CRA, OA and PCA showed a statistically significant reduction when comparing baseline values in both injected and uninjected fellow eyes (p = 0.0001). Also, it was found a significant increase in the post-injection RI values of all the CRA, OA, PCA in injected eye and OA in the uninjected eye (p = 0.0001). There was any significant difference between pre- and post-injection RI values of the CRA and PCA in the fellow eyes (p = 0.137, p = 0.736, respectively). CONCLUSION: Single intravitreal administration of aflibercept alters retrobulbar blood flow velocities (BFVs) in both injected and uninjected fellow eyes in the short-term period.

Doppler ultrasonographic measurement of short-term effects of valsalva maneuver on retrobulbar blood flow.

BACKGROUND: To investigate the effects of Valsalva maneuver (VM) on retrobulbar blood flow parameters in healthy subjects. METHODS: Participants without any ophthalmologic or systemic pathology were examined in supine position with color and pulsed Doppler imaging for blood flow measurement, via a paraocular approach, in the ophthalmic artery (OA), central retinal artery (CRA), central retinal vein (CRV), nasal posterior ciliary artery (NPCA), and temporal posterior ciliary artery (TPCA), 10 seconds after a 35- to 40-mm Hg expiratory pressure was reached. Peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistivity index (RI) values were recorded for each artery. PSV and EDV values were recorded for CRV. RESULTS: There were significant differences between resting and VM values of PSV and EDV of CRA, RI of NPCA, and PI, RI, and EDV of TPCA. Resting CRA-EDV, CRV-PSV, and CRV-EDV were positively correlated whereas resting OA-PSV and CRA-PI, and OA-PSV, CRA-PSV, and CRA-EDV during VM, were negatively correlated with age. CONCLUSIONS: VM induces a short-term increase in CRA blood flow and a decrease in NPCA and TPCA RI. Additional studies with a longer Doppler recording during VM, in a larger population sample, are required to allow definitive interpretation. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:551-555, 2017.

[Influence of long-time video operation on hemodynamics of the retrobulbar arteries in operators].

Objective: To investigate the influence of long-time video operation on hemodynamics of the retrobulbar arteries in operators. Methods: From March to October, 2015, a total of 120 soldiers for office work engaged in video surveillance were enrolled as study group, and 155 fire fighters were enrolled as control group. The incidence of eye discomfort was compared between the two groups. Color Doppler ultrasound was used to measure and compare the peak systolic velocity (PSV) , end-diastolic velocity (EDV) , and resistance index (RI) of the central retinal artery (CRA) and the short posterior ciliary artery (SPCA) , and the correlation of video operation time with the hemodynamic parameters of the retrobulbar arteries was analyzed. Results: The study group had a significantly higher incidence rate of eye discomfort than the control group (P<0.05) . Compared with the control group, the study group had significant reductions in the PSV and EDV of the CRA and the SPCA and a significant increase in the RI of the CRA (P<0.05) . Video operation time was negatively correlated with the PSV and EDV of the CRA and the SPCA (r=-0.61, -0.54, -0.65, and-0.68, all P<0.05) and positively correlated with the RI of the CRA and the SPCA (r=0.56 and 0.63, P<0.05) . Conclusion: Long-time video operation can increase the incidence of eye discomfort and lead to increased blood resistance of the CRA and the SPCA and reduced retinal perfusion.

Ocular perfusion pressure and color Doppler imaging of the external ophthalmic artery of rabbits treated with sildenafil citrate.

BACKGROUND: It has been proposed that sildenafil citrate can increase ocular blood flow, and that this property can be used to treat ocular disorders that involve reflex vasoconstriction. This study therefore proposes to ascertain the vasodilator effect of the drug on retrobulbar circulation in healthy rabbits. For this matter rabbits treated with sildenafil citrate or saline solution had their intraocular pressure (IOP), mean arterial pressure (MAP), ocular perfusion pressure (OPP) and color Doppler imaging of the external ophthalmic artery measured prior to treatment and on days one (moment M1), seven (when M2), fourteen (moment M3), twenty-one (moment M4), and thirty (moment M5) of treatment. RESULTS: The MAP and OPP values of treated group were lower than those of control group at all times, and the mean values differed statistically at moments M1 (S = 71.52 mmHg, C = 84.76 mmHg, p = 0.0356) and M5 (S = 71.38 mmHg, C = 85.52 mmHg, p = 0.0252). The IOP and color Doppler values of the external ophthalmic artery did not differ between tested groups. CONCLUSIONS: The dose of 10 mg of sildenafil citrate administered to healthy rabbits causes systemic vasodilation and consequently lower values of MAP and OPP. However, it does not induce changes in IOP and retrobulbar hemodynamics identifiable by color Doppler assessment of the external ophthalmic artery.

Ocular perfusion pressure and ophthalmic artery flow in patients with normal tension glaucoma.

BACKGROUND: Vascular insufficiency has been reported to be a cause of normal tension glaucoma (NTG). The aim of this study was to compare ocular perfusion pressure (OPP) and ophthalmic artery flow (OAF) between patients with NTG and those without glaucoma. METHODS: We considered one eye each from 31 NTG and 15 non-glaucoma control patients. Blood pressure and intraocular pressure (IOP) were measured in the sitting position, for calculation of OPP. Humphrey visual field (HVF) assessment was then carried out on NTG patients. All patients then underwent Transcranial Doppler ultrasound measurements of OAF parameters, including mean flow velocity (MFV), end diastolic velocity (EDV), peak systolic velocity (PSV) and resistive index (RI). We looked at differences in OPP and OAF parameters between the two groups, and their correlations in NTG patients. T-tests, χ (2), ANOVA and Pearson Correlation tests were performed, with p < 0.05 considered statistically significant. RESULTS: There were no statistically significant differences in OPP between the NTG and control groups (60.5+/-8.7 mmHg and 62.9+/-10.2 mmHg respectively, p = 0.393), and also no statistically significant differences in MFV, EDV, PSV and RI (all p > 0.05). In the NTG group, there were positive correlations between OPP and both MFV (r = 0.416, p = 0.020) and EDV (r = 0.369, p = 0.041). There were no statistically significant correlations between HVF mean deviation and OPP or OAF parameters (all p > 0.05). CONCLUSION: There is no difference in OPP and OAF parameters between patients with NTG and non-glaucoma controls, suggesting that vascular insufficiency or dysregulation by themselves may not account for the pathogenesis of NTG.

Effect of enhanced extracorporeal counterpulsation in patients with non-arteritic anterior ischaemic optic neuropathy.

PURPOSE: The purpose is to study the effect of Enhanced Extracorporeal Counterpulsation (EECP) in patients with non-arteritic anterior ischaemic optic neuropathy (NAION). METHODS: EECP is a noninvasive, mechanical, and circulatory support therapy. Sixteen patients with unilateral NAION were treated with EECP (twelve 1-h daily treatment sessions for each patient). Color Doppler imaging (CDI) was applied to measure the mean flow velocity (MFV), peak-systolic velocity (PSV), end-diastolic velocity (EDV) of the ophthalmic artery (OA) and central retinal artery (CRA). Intraocular pressure (IOP) was measured by Goldmann applanation tonometry. Measurements were collected before and immediately after the first and the last sessions of EECP in both eyes, and they were compared with the baseline measurement before EECP. The measurements were also compared between the NAION eyes and the normal fellow eyes. Visual acuity (VA) and visual field (VF) were assessed before EECP and after the last EECP. RESULTS: EECP progressively increased blood flow velocities of the OA and CRA and progressively decreased IOP in both eyes (P < 0.05). After the first session of EECP, there was a 16 ± 5.3% increase in EDV and a 13.9 ± 9.5% increase in MFV of the OA, and a 17.1 ± 2.5% increase in PSV, a 21.2 ± 9.3% increase, in EDV and a 16.5 ± 3.3% increase in MFV of the CRA in NAION eyes. After the last EECP treatment, there was a 16.8 ± 6.7% increase in EDV and a 14.0 ± 5.1% increase in MFV of the OA, and a 17.7 ± 12.3 % increase in PSV, a 23.1 ± 6.3% increase in DSV, and a 21.1 ± 8.4% increase in MFV of the CRA in NAION eyes (P < 0.05). The change of the PSV, EDV, and MFV in the CRA were more significant in NAION eyes than that of their fellow eyes (P < 0.05). VA was improved and VF mean deviation was decreased in NAION eyes after the last EECP treatment (P = 0.003 and 0.049, respectively), and VA improvement was correlated positively with the blood flow parameter. CONCLUSIONS: EECP could be a clinically effective and safe treatment for NAION.

Reproducibility of retrobulbar blood flow velocity measurements in normal subjects using two different CDI devices.

PURPOSE: This study was done to evaluate the intra- and inter-operator reproducibility of colour Doppler imaging (CDI) in assessing blood flow velocity in the ophthalmic (OA), central retinal (CRA) and short posterior ciliary arteries (SPCA) in healthy subjects. MATERIALS AND METHODS: The right eye of two groups of eight healthy volunteers was examined. Two radiologists and two ophthalmologists, divided into pairs, measured peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistivity index (RI) of each vessel using a different CDI device for each group. The concordance between two measurements was evaluated with Lin's concordance correlation coefficient (CCC). RESULTS: Globally, very good degrees of intra-operator concordance were obtained for the PSV (0.859 cm/s), EDV (0.834 cm/s) and RI (0.859) of the OA. There was moderate concordance for PSV (0.574 cm/s) and EDV (0.594 cm/s) and good concordance for RI (0.694) for the CRA. Good degrees of concordance were obtained for the SPCA measurements. However, inter-operator concordance was found globally poor. CONCLUSIONS: These data show that CDI measurements in retrobulbar vessels are operator dependent. To increase the intra-operator and inter-operator concordance, rules should be adopted for timing of the examination and positioning of the probe to minimise the pressure applied on the eye.

Role of nitric oxide synthase isoforms for ophthalmic artery reactivity in mice.

Nitric oxide synthases (NOS) are involved in regulation of ocular vascular tone and blood flow. While endothelial NOS (eNOS) has recently been shown to mediate endothelium-dependent vasodilation in mouse retinal arterioles, the contribution of individual NOS isoforms to vascular responses is unknown in the retrobulbar vasculature. Moreover, it is unknown whether the lack of a single NOS isoform affects neuron survival in the retina. Thus, the goal of the present study was to examine the hypothesis that the lack of individual nitric oxide synthase (NOS) isoforms affects the reactivity of mouse ophthalmic arteries and neuron density in the retinal ganglion cell (RGC) layer. Mice deficient in one of the three NOS isoforms (nNOS-/-, iNOS-/- and eNOS-/-) were compared to respective wild type controls. Intraocular pressure (IOP) was measured in conscious mice using rebound tonometry. To examine the role of each NOS isoform for mediating vascular responses, ophthalmic arteries were studied in vitro using video microscopy. Neuron density in the RGC layer was calculated from retinal wholemounts stained with cresyl blue. IOP was similar in all NOS-deficient genotypes and respective wild type controls. In ophthalmic arteries, phenylephrine, nitroprusside and acetylcholine evoked concentration-dependent responses that did not differ between individual NOS-deficient genotypes and their respective controls. In all genotypes except eNOS-/- mice, vasodilation to acetylcholine was markedly reduced after incubation with L-NAME, a non-isoform-selective inhibitor of NOS. In contrast, pharmacological inhibition of nNOS and iNOS had no effect on acetylcholine-induced vasodilation in any of the mouse genotypes. Neuron density in the RGC layer was similar in all NOS-deficient genotypes and respective controls. Our findings suggest that eNOS contributes to endothelium-dependent dilation of murine ophthalmic arteries. However, the chronic lack of eNOS is functionally compensated by NOS-independent vasodilator mechanisms. The lack of a single NOS isoform does not appear to affect IOP or neuron density in the RGC layer.

Retrobulbar and common carotid artery haemodynamics and carotid wall thickness in patients with non-arteritic anterior ischaemic optic neuropathy.

PURPOSE: To evaluate retrobulbar and common carotid artery (CCA) haemodynamics and CCA wall thickness in the patients with acute unilateral non-arteritic anterior ischaemic optic neuropathy (NAION) by colour Doppler imaging (CDI). METHODS: Twenty-two patients with acute unilateral NAION and 28 age- and sex-matched controls were included in this prospective study. By CDI, the peak-systolic velocity (PSV) and end-diastolic velocity (EDV) of the ophthalmic artery (OA) and central retinal artery (CRA) in both eyes were measured or calculated. Intima-media thickness (IMT) and blood flow velocity were measured in both CCAs. Measurements on the affected side of the patients were compared to the contralateral healthy side and the controls. RESULTS: Compared to the controls, the blood flow velocities in the CRA were significantly decreased (p < 0.05), and IMT of CCA was greater (p < 0.001) on the affected side, while the blood flow velocities in the OA and CCA showed no statistically significant difference. The blood flow velocities in the CRA tended to be reduced bilaterally in the patients with NAION, and the difference of PSV and EDV was insignificant between the affected eyes and fellow eyes (p = 0.69, 0.86 respectively). No marked differences between the controls and the unaffected sides were detected, neither for the blood flow velocities in CRA, OA, CCA nor for the IMT of CCA. CONCLUSION: Decreased blood velocities of CRA and increased carotid wall thickness were found on the affected side of acute NAION compared to healthy controls. These findings might be potentially useful in the treatment monitoring of NAION.