Orbital Vasculature Research Articles

Color Doppler imaging of the eye: normal ranges, reproducibility, and observer variation.

Color Doppler ultrasonography has numerous potential applications in the diagnosis and monitoring of many ocular disease processes. One of its advantages over other investigative and diagnostic tests is its safety and repeatability. To be able to fully assess this technique it is important to have good control data and to know the reproducibility of the technique for each of the retrobulbar vessels. Color Doppler ultrasonography was performed on 80 volunteers, and normal ranges of blood velocity were calculated for the ophthalmic artery and for the central retinal artery and vein. Reduction in the peak systolic and end diastolic velocities in the ophthalmic artery and an increase in resistive index in the central retinal artery and vein were noted with advancing age. With regard to reproducibility of the retrobulbar vessels, 15 healthy persons were chosen at random and intra- and interobserver studies performed. The most reliable and reproducible vessels were the ophthalmic artery and central retinal artery and vein. Greater variation was noted in the posterior ciliary vessels, whereas the superior ophthalmic and vortex veins were unreliable in both detection and velocity measurement. The results provide normal ranges for future studies and demonstrate that reproducible results can be obtained for the orbital vasculature using color Doppler imaging.

Central Retinal Vein Occlusion, an Investigation by Color Doppler Imaging: Blood Velocity Characteristics and Prediction of Iris Neovascularization

To determine pulsatile blood velocities in the orbital vasculature in patients with central retinal vein occlusion (CRVO). The ophthalmic artery, central retinal artery, and vein of 80 patients with CRVO and 95 control subjects were investigated by color Doppler imaging. The patients were examined by ophthalmoscopy, relative afferent pupillary measurement using cross-polarized filters, fundus fluorescein angiography, and electroretinography to estimate the degree of retinal ischemia. Blood flow velocities in the central retinal vein and artery of eyes with CRVO were significantly lower than in fellow eyes and controls. The measurements from the vein were most reduced and in some cases absent in those eyes with "ischemic" CRVO. Velocities also were reduced in the central retinal artery of the affected eyes, but no correlation with "ischemia" was detected. The risk of iris neovascularization in patients examined within 3 months of onset of CRVO can be determined from the flow velocities with a high degree of predictability (75% sensitivity and 86% specificity). Blood velocity was reduced in the retinal circulation of patients with CRVO and reduced even further in the "ischemic" variant of CRVO. The results indicate that noninvasive color Doppler imaging could play a major part in the routine assessment of patients with CRVO within 3 months of onset.

Retinal vasospasm associated with visual disturbance in preeclampsia: Color flow Doppler findings

This case report demonstrates retinal vasospasm during a period of visual disturbance in a patient with preeclampsia. Doppler assessment of the orbital vasculature was performed during and after the episode. Central retinal artery blood velocity increased, and resistance decreased, after resolution of symptoms. Visual disturbances in preeclampsia may be associated with retinal artery vasospasm and ischemia.

Colour Doppler velocimetry of the arterial vasculature of the optic nerve head and orbit

Blood flow in the orbital vasculature can be investigated by colour Doppler velocimetry which allows simultaneous imaging of B-scan and Doppler ultrasound. In this paper we review the results of our recent studies on the arterial vasculature of the orbit and optic nerve head. A control study is described in which reliable measurements were obtained from the ophthalmic artery at the orbital apex, the medial orbit, and the complex of the central retinal artery and posterior ciliary arteries. Patients with occlusion of the central retinal artery and posterior ciliary arteries were examined. The results indicate that readings at the optic nerve head primarily represent blood flow in the central retinal artery. A study of the effects of posture on velocimetry demonstrated no change in the measurements obtained. Finally, topical timolol 0.5% was found to reduce the resistive indices of flow in the central retinal artery.

Experimental intravenous digital subtraction angiography (DSA) of orbital and choroidal circulation: preliminary study.

The development of the radiologic technique, digital subtraction angiography (DSA), has substantial importance in studying the uveal vasculature and its orbital blood supply. After rapid intravenous injection of commercially available contrast material, images of the orbital and uveal vessels of rabbits, cats, and the nonhuman primate can be observed. Advantages and limitations of this new technique for visualization of uveal and orbital vasculature were evaluated in serial experimental animal studies. Future potential clinical applications are discussed.

Ultrasonic examination of orbital vasculature

Patients with orbital varices form a diagnostically important group of those referred for ultrasonic study of orbital proptosis. Two cases are presented in which diagnosis of dilated orbital blood vessels was established by B scan ultrasonography. The echographic appearance of normal and dilated orbital vessels is discussed.

Orbital vascular anatomy and embryology.

Serial direct magnification angiography enhances detailed orbital vasculature apart from the surrounding vessels and aids in the diagnosis of orbital neoplasms. Selective techniques show branches of the internal and external carotid arteries supplying the orbit and their important anastomotic channels. The dual blood supply to the orbit is structured on embryological origins.

Studies of intracranial and orbital vasculature of the rhesus monkey (Macaca mulatta)

Studies of intracranial and orbital vasculature of the rhesus monkey (<i>Macaca mulatta</i>)