Reversible abnormalities in the ophthalmic arteries detected by color Doppler imaging

Effects of Obstructive Carotid Artery Disease on Ocular Circulation and the Safety of Carotid Artery Stenting

BACKGROUND

The aims of this study were to examine the ophthalmic artery flow changes in patients with obstructive carotid artery disease, evaluate the orbital blood flow changes after carotid artery stenting and assess the safety of carotid stenting procedure by using transorbital colour and spectral Doppler sonography.

METHODS

Thirty-one consecutive patients scheduled for carotid stenting with severe internal carotid artery stenosis (>60%; the study group) and 30 control subjects were included. Ophthalmic artery (OA) Doppler sonography was performed in the control group and study group before and after stenting. Peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistive index (RI) and systolic/diastolic ratio (S/D) in the ophthalmic artery were recorded. Statistical comparisons were made between controls and study group before stenting and before and after stenting in the study group.

RESULTS

Comparison between control and study group before stenting revealed a statistically significant decrease in OA PSV (51.5±14.5 vs. 39.7±19cm/sec, p= 0.008) and EDV (15.2±4.5 vs. 11.3±5.7cm/sec, p=0.004) in the study group. Differences in PI (1.3±0.14 vs. 1.36±0.4, p=0.47), RI (0.7±0.04 vs. 0.75±0.21, p=0.19), and S/D (3.5±0.6 vs. 3.6±1, p= 0.5) ratio were not statistically significant between groups. Peak systolic velocity (39.7±18.9 vs. 51.3±22.2cm/sec, p <0.001), RI (0.75±0.21 vs. 0.81±0.13, p=0.16) and S/D ratio (3.6±1 vs. 4.6±1.5, p= 0.001) were found to be significantly increased in the study group after stenting compared to baseline. There were no statistically significant differences in EDV and RI EDV(11.3±5.7 vs. 11.7±5.7cm/sec, p=0.66), PI (1.36±0.4 vs. 1.6±0.6, p =0.047) after stenting.

CONCLUSIONS

Ophthalmic artery flow parameters were significantly lower in patients with severe carotid artery stenosis compared to control, indicating compromised ocular blood flow in severe carotid stenosis. Flow indicators significantly improved after stent implantation suggesting the importance of revascularisation in restoring ocular blood flow and safety of carotid stenting.

Right-to-left-shunt detected by c-TCD using the orbital window in comparison with temporal bone windows

PURPOSE

There have been some reports on right-to-left shunt as a cause of cryptogenic stroke. Although contrast transcranial Doppler (c-TCD) can detect RLS, an insufficient temporal window has occasionally restricted its applicability. Thus, we compared the rates of detecting RLS among temporal windows for the middle cerebral arteries (MCAs) and the orbital window for the internal carotid artery (ICA) on c-TCD.

METHODS

We used c-TCD to detect RLS in patients with suspected ischemic stroke. We enrolled patients who had both sufficient bilateral temporal windows for MCAs and a right orbital window for ICA and performed c-TCD using all three windows simultaneously.

RESULTS

We enrolled 106 consecutive patients and identified microembolic signals (MES) in 30 (28%) of them. Among these 30 patients, 15 had MES from all 3 windows. When these 30 patients were defined as being positive for RLS, the rates of detection were 67%, 73%, and 80% from the right temporal, left temporal, and right orbital windows, respectively (P= .795).

CONCLUSION

The right orbital window as well as the temporal window for c-TCD could detect RLS. Insonation from the orbital window should be useful for patients who lack temporal windows.

Perimetric and retrobulbar blood flow changes following carotid endarterectomy

BACKGROUND

Carotid stenosis can produce visual changes. This study examines perimetric and retrobulbar blood flow changes following carotid endarterectomy (CEA) in patients without visual symptoms.

METHODS

Sixteen patients (13 male, three female) with bilateral carotid stenosis were included. Patients with a history of ophthalmic disease, including glaucoma, were excluded. Peak systolic velocity (PSV) in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCAs) was measured preoperatively and 12 months following CEA with color Doppler imaging (CDI), using a 7.5 MHz probe, at both the side operated upon and its fellow side. Automated static perimetry (Octopus 500 perimeter, G1x program) was performed at the same intervals. Mean sensitivity (MS), mean defect (MD), loss variance (LV) and corrected loss variance (CLV) were recorded.

RESULTS

Preoperative PSV in the OA was significantly lower in the side operated on. Preoperative perimetric parameters were significantly compromised, compared with normative data, in both eyes. Postoperatively, PSV had significantly improved in all vessels examined in the carotid that was operated on, but only in the OA and SPCAs in the fellow side. MD had significantly improved postoperatively for both eyes, whereas improvement in the other perimetric parameters examined was not statistically significant.

CONCLUSIONS

Perimetric changes occur in carotid stenosis. CEA results in the improvement of retrobulbar blood flow and perimetric parameters. Further research will be required to determine whether perimetric parameters may be used as additional indicators for carotid endarterectomy.

Reversible anterior segment ischaemia after carotid endarterectomy

Carotid artery disease has long been implicated in ocular ischaemic syndrome. The classical changes of ocular ischaemic syndrome have not been described to resolve with carotid endarterectomy. Herein, a case of documented carotid artery disease presenting with anterior segment ischaemia and retinal artery emboli is described. Prompt carotid endarterectomy resulted in resolution of most of the anterior segment ischaemic signs within a few days.

Normal reference intervals and ranges of side-to-side and day-to-day variability of ocular blood flow Doppler parameters

The study presents normal reference intervals and ranges of "normal" side-to-side and day-to-day variability of ocular blood flow Doppler parameters. Peak-systolic (PSV), end-diastolic velocity (EDV) and impedance indices in the ophthalmic artery (OA), the central retinal artery (CRA) and the short posterior ciliary artery (SPCA) of both orbits were determined with color-coded duplex sonography in 140 healthy volunteers (range 18 to 83 y; 68 men and 72 women). Decreases in flow velocities and concomitant increases in impedance indices were found in all arteries with advancing age. The PSV and the EDV values for the OA, the CRA and the SPCA in the age group less than 40 yr-old were 40.6 +/- 8.9 and 11.2 +/- 3.7, 9.9 +/- 1.8 and 3.7 +/- 0.9, 13.8 +/- 2.6 and 5.7 +/- 1.5 cm/s (mean +/- SD), respectively. In the 40 to 60 yr-old age group, the values were 35 +/- 7.9 and 10.7 +/- 4.3, 9.7 +/- 2 and 3.5 +/- 0.8, 13.5 +/- 2.9 and 5.3 +/- 1.5 cm/s. In the age group over 60 yr-old, the values were 34 +/- 8 and 8.4 +/- 3.3, 9.3 +/- 2 and 3 +/- 0.9, 12.8 +/- 2.4 and 4.3 +/- 1.2 cm/s. In the youngest age group, the EDV in the CRA and the SPCA was higher in women, while in the OA the PSV and the EDV were higher in men. Ranges of side-to-side variability in the OA, the CRA and the SPCA, determined with repeatability coefficient for the PSV and the EDV, were 24, 5.4, 7.5 cm/s and 11, 2.5, 4.2 cm/s, respectively, whereas the values for day-to-day variability were 16.8, 4.3, 6.7 cm/s and 5.6, 1.7 and 3.9 cm/s. Ocular blood flow Doppler parameters range widely and are significantly age and sex dependent. Ranges of "normal" side-to-side and day-to-day variability of the parameters can help to determine abnormal flow pattern.

Progressive changes in ophthalmic blood velocities in Beagles with primary open angle glaucoma

OBJECTIVE

To measure changes in the ocular and orbital blood flow velocities by color Doppler imaging (CDI) in beagles with primary open angle glaucoma as the disease progressed from early to advanced stages.

METHODS

CDI measurements were performed periodically on 13 glaucomatous Beagles during the nontreated mild, moderate and advanced stages of POAG over the course of 4 years. CDI was performed with the dogs lightly anesthetized (butorphanol 0.1 mg/kg IV, acepromazine maleate 0.02 mg/kg IV, and atropine sulfate 0.05 mg/kg) while the CD transducer was placed directly on the cornea anesthetized with 0.5% tetracaine hydrochloride. Intraocular pressure (IOP) by pneumatonography or TonoPen XL, heart rate and mean arterial blood pressure were measured at the beginning, middle and end of each study. The ophthalmic vessels examined included: external ophthalmic arteries and veins, long and short posterior ciliary arteries, anterior ciliary arteries and veins, primary retinal arteries, and vortex veins. Recordings of each vessel included peak systolic velocity (PSV), end diastolic velocity (EDV) and time averaged velocity (TAV), and when possible the resistive index (RI) and pulsatility index (PI) were computed.

RESULTS

CDI abnormalities were present before intraocular pressure exceeded the normal range. As the animals aged, and the glaucoma progressed with higher levels of IOP, significant changes occurred in nearly all vessels, and generally included a major increase in RI (P < 0.001) and an increase in the PI (P < 0.001). Mean arterial blood pressure (105 +/- 18 mmHg) and heart rate (118 +/- 33/min) remained reasonably constant. The IOP gradually increased as the disease progressed (early and normotensive: 19.4 +/- 3.9 mmHg; moderate: 29.7 +/- 2 mmHg; and advanced: 44.5 +/- 6 mmHg). The ocular veins seemed most influenced early on in the disease. Late in the disease, ocular venous blood flow could not be consistently demonstrated. An increase in the PI of ocular veins occurred in the moderately and severely affected glaucomatous Beagles. As the IOP increased, there were trends of increasing resistive index and pulsatility index in most arteries, and periods of marked decreased velocities of the vortex and external ophthalmic veins in severe cases.

CONCLUSION

CDI measurements in Beagles with primary open angle glaucoma during the course of 4 years indicate easily measurable and repeatable progressive blood flow abnormalities before the elevation of IOP and, thereafter, with gradually increased levels of IOP.

Use of color doppler imaging for determining the resistive index of the medial long posterior ciliary artery in clinically normal conscious dogs

OBJECTIVE

To evaluate the use of color Doppler imaging (CDI) for determining the resistive index (RI) of the medial long posterior ciliary artery (mLPCA) in clinically normal conscious dogs.

ANIMALS

18 (10 sexually intact males, 8 sexually intact females) dogs between 1 and 5 years old.

PROCEDURE

Color Doppler ultrasonography was performed on both eyes with dogs in a sitting position. Each eye was imaged from the region dorsal to the zygomatic arch with the transducer positioned in a horizontal plane. The mLPCA was localized, and RI was calculated from velocities obtained for 3 similar Doppler waveforms. To determine the reproducibility of CDI-derived RI, measurements were repeated twice at a 10-day interval.

RESULTS

Mean (+/- SD) RI of the mLPCA was 0.68 +/- 0.07 (95% confidence interval, 0.65 to 0.70; n = 36 eyes). Resistive index did not significantly differ between right and left eyes or male and female dogs. In addition, body weight was not correlated with RI. Repeated measurements of RI did not yield significantly different results (interclass correlation coefficient, 0.8297).

CONCLUSION AND CLINICAL RELEVANCE

Color Doppler imaging appears to be a valid technique for determination of RI of the mLPCA in conscious dogs. This technique may be useful for investigating the pathophysiologic processes of many ocular and orbital vascular disorders in dogs.

Ocular ischaemic syndrome

Ocular ischaemic syndrome is a rare condition. It often results in blindness and is linked to serious systemic morbidity. Its presentation is usually subtle and it can be misdiagnosed due to its diverse signs and symptoms. A case of ocular ischaemic syndrome is presented and current diagnostic procedures and treatment described. Recognition by the clinician is important because of the severe ocular and potential systemic sequelae.

Assessment of ocular perfusion after carotid endarterectomy with color-flow duplex scanning

PURPOSE

The purpose of this study was to assess the effect of carotid endarterectomy (CEA) on ocular perfusion with the measurement of the ophthalmic artery (OA) and the central retinal artery (CRA) flow velocities with color-flow ocular duplex scanning (ODS). Ocular hemodynamics also were examined in a subset of patients with visual symptoms in an attempt to characterize the origin of the ocular symptoms and their response to surgery.

METHODS

Twenty-five patients with internal carotid artery stenoses (>/=70%) underwent 29 CEAs. All the patients underwent ODS for the measurement of the peak systolic velocity (PSV) in the OA and the CRA of the ipsilateral eye before and after CEA. The preoperative and postoperative flow velocities were compared in all the patients and in the patients with and without visual symptoms.

RESULTS

The preoperative PSV in the OA was 21.6 +/- 2.2 cm/s and in the CRA was 7.7 +/- 0.7 cm/s. These values were reduced as compared with normative values (OA, 37.8 cm/s; CRA, 10.7 cm/s). After CEA, the PSV increased significantly in both vessels (postoperative OA, 38.6 +/- 2.5 cm/s, P <.0001; postoperative CRA, 12.1 +/- 0.9 cm/s, P =.0008). Fifteen of the 29 CEAs were performed for visual symptoms. The patients with ocular symptoms had significantly lower preoperative PSVs in the CRA as compared with those patients without visual symptoms (CRA with ocular symptoms, 6.5 +/- 0.8 cm/s; CRA with no ocular symptoms, 9.4 +/- 0.9 cm/s; P =.02). The PSV in the OA was not significantly lower in the patients with ocular symptoms. Eight patients (28%) were found to have reversed OA flow before surgery, but only three patients had ocular symptoms. All eight patients had normal antegrade flow in the OA after surgery.

CONCLUSION

Severe carotid stenosis may be associated with reduced ocular perfusion, which can be quantitatively evaluated with ODS. Reduced OA and CRA flow velocities are corrected with successful CEA. The patients with ocular symptoms were observed to have significant reductions in CRA flow velocities. Reversed flow in the OA was not a marker for ocular symptoms in this study. ODS can identify global ocular ischemia and may be helpful in the evaluation of patients with atypical visual symptoms or with amaurosis fugax and no evidence of retinal emboli.

The effects of carotid endarterectomy on the retrobulbar circulation of patients with severe occlusive carotid artery disease. An investigation by color Doppler imaging

OBJECTIVE

To analyze the effects of carotid endarterectomy on the retrobulbar circulation of patients with severe occlusive carotid artery disease (OCAD) by means of color Doppler imaging (CDI).

DESIGN

Prospective.

PARTICIPANTS

A total of 17 consecutive patients with severe OCAD and neurologic symptoms (with a history of transitory ischemic attack or cerebral vascular accident) participated.

INTERVENTION

All 17 patients underwent carotid endarterectomy. The CDI of both orbits was performed by one masked investigator before surgery and at 1 week and 1 month after surgery.

MAIN OUTCOME MEASURES

Peak systolic velocity, end diastolic velocity, and resistive index of the ophthalmic, central retinal, and temporal short posterior ciliary arteries were measured. The authors compared the hemodynamic parameters at all intervals.

RESULTS

Peak systolic and end diastolic velocities in the ophthalmic, central retinal, and temporal short posterior ciliary arteries increased significantly 1 week and 1 month after carotid endarterectomy (P < 0.05). After surgery, the resistive indices in the central retinal and temporal short posterior ciliary arteries decreased significantly at both intervals (P < 0.05). The six patients who had reversed ophthalmic artery flow before surgery showed forward ophthalmic artery flow after carotid endarterectomy. The contralateral orbits showed no significant hemodynamic change after endarterectomy (P < 0.05).

CONCLUSIONS

Hemodynamic changes in patients with severe OCAD undergoing carotid endarterectomy suggest improvement in the ipsilateral retrobulbar blood flow.

The effects of carotid endarterectomy on ocular haemodynamics

PURPOSE

To determine the profile of blood flow velocities and resistive indices in the ocular vessels of patients with atherosclerotic carotid disease and characterise the effect of endarterectomy on these parameters.

METHODS

Following a preliminary study on healthy volunteers, ophthalmic colour Doppler ultrasound examinations were performed on 27 male and 11 female patients with carotid disease. These measurements were compared with central retinal artery perfusion pressures and intraoperative internal carotid artery stump pressures.

RESULTS

Significant changes were seen on the endarterectomised side. The peak systolic velocity in the ophthalmic artery, and resistive indices in the ophthalmic artery, central retinal artery and nasal posterior ciliary artery, rose from pre-operative values. No correlation between colour Doppler ultrasound measurements and intraoperative internal carotid artery stump pressures was present. When compared with ophthalmodynamometry readings, a relationship was noted with maximum velocities in the central retinal vein.

CONCLUSION

Carotid endarterectomy alters the haemodynamics in selected vessels of the ocular circulation as measured by colour Doppler ultrasound, but more work is required to determine the clinical utility of this investigative modality.

Assessment of human ocular hemodynamics

Vascular abnormality and altered hemodynamics play important roles in many ophthalmic pathologies. Much of our knowledge of ocular hemodynamics was gained from invasive animal research, although a number of noninvasive methods suitable for in vivo use in humans have been developed. Data from these methods now produce a significant literature of their own. Understanding the origins of the data and appreciating their limitations can be difficult. Modern hemodynamic assessment techniques each examine a unique facet of the ocular circulation. No single facet provides a complete description of the hemodynamic state of the eye. These methods have contributed a great deal to our understanding of normal hemodynamics. More importantly, they continue to add to our understanding of altered hemodynamics found in disease. Some have found their way into limited clinical practice. The predominant ocular hemodynamic assessment techniques are reviewed with the aims of introducing the fundamental principles behind each, highlighting their inherent advantages and limitations, highlighting their contributions to understanding ocular physiology, and considering their potential to provide signs for diagnosis.