Related Experiment Video
Updated: Aug 15, 2026
Doppler Optical Coherence Tomography of Retinal Circulation
Published on: September 18, 2012
Flow velocity of central retinal artery and retrobulbar vessels during cardiovascular operations
K Orihashi1, Y Matsuura, T Sueda
1First Department of Surgery, Hiroshima University School of Medicine, Japan.
Insights
Monitoring central retinal artery blood flow using orbital vessels can determine critical closing pressure and confirm the circle of Willis patency. The eye serves as an acoustic window into intracranial blood flow during cardiovascular surgery.
Area of Science:
- Ophthalmology
- Cardiovascular Surgery
- Neuroscience
Background:
- Adequate cerebral perfusion is critical during cardiovascular operations, necessitating both blood flow and pressure monitoring.
- Transcranial Doppler ultrasonography can yield inconsistent signals, particularly during cardiopulmonary bypass.
Purpose of the Study:
- To evaluate the central retinal artery's blood flow as a reflection of carotid artery obstruction.
- To assess the utility of orbital vessel monitoring in cardiovascular surgery.
Main Methods:
- Utilized a 5 or 7.5 MHz echocardiographic probe in 28 patients.
- Correlated maximal velocity in the central retinal artery with systolic blood pressure.
- Examined central retinal artery and retrobulbar vessel blood flow during various perfusion and circulatory support techniques.
Main Results:
- Blood flow in the central retinal artery was visualized and pressure-dependent, disappearing below a critical threshold.
- Systolic blood pressure strongly correlated with maximal velocity (r = 0.6902, p < 0.0001).
- Determined a "critical closing pressure" of 35.8 +/- 14.8 mm Hg, with individual variations observed. Pulsatility index significantly increased post-cardiopulmonary bypass (p < 0.0001).
Conclusions:
- Orbital vessel monitoring effectively provides critical closing pressure of the central retinal artery.
- This method confirms the patency of the circle of Willis, offering insights into intracranial blood flow.
- The eye acts as a valuable "acoustic window" for monitoring cerebral blood flow during cardiovascular procedures.
Objective:
Both blood flow monitoring and pressure monitoring are necessary to avoid inadequate cerebral perfusion during cardiovascular operations. Inasmuch as transcranial Doppler ultrasonography does not provide a consistently good signal, especially during cardiopulmonary bypass, we examined the blood flow through the central retinal artery, which has proved to reflect an obstruction of the carotid artery.
Method:
Twenty-eight consecutive cases were examined with a 5 or 7.5 MHz conventional echocardiographic probe. Correlation between the maximal velocity at the central retinal artery and systolic blood pressure was examined. The blood flow of the central retinal artery and retrobulbar vessels was examined during selective or retrograde cerebral perfusion or intraaortic balloon pumping.
Results:
Blood flow could be clearly visualized but disappeared below a certain pressure in every case. With data from 478 measuring points, systolic blood pressure correlated with maximal velocity (r = 0.6902, p < 0.0001). The blood pressure-axis intercept, known as "critical closing pressure," was 35.8 +/- 14.8 mm Hg, varying among individuals and bilateral eyes. Pulsatility index increased after cardiopulmonary bypass (1.095 +/- 0.245 to 1.525 +/- 0.268, p < 0.0001). Patency of the circle of Willis was confirmed by the blood flow during anastomosis of the ipsilateral artery. During retrograde cerebral perfusion, blood flow was detectable at the retrobulbar vessels. During intraaortic balloon pumping, the central retinal artery flow was augmented on inflation of the balloon.
Conclusion:
Orbital vessel monitoring provides the critical closing pressure of the central retinal artery and confirms patency of the circle of Willis. The eye can be "an acoustic window" into intracranial blood flow during cardiovascular surgery.
