Color Doppler imaging makes it possible for the first time to assess the blood flow velocity of orbital vessels. Especially in Graves disease, with its increase of orbital contents, this technique allows detection of changes in the perfusion of retrobulbar arteries and veins. We examined 23 patients (19 female, 4 male, average age 47.9 years) with thyroid ophthalmopathy using color Doppler imaging. Central retinal artery and vein, posterior ciliary arteries, vortex veins, superior orbital vein and ophthalmic artery were located and their Doppler spectra analysed. Results were compared with observations recorded in a control group consisting of 105 healthy volunteers. The thicknesses of extraocular muscles were measured echographically.
Results: There was no significant difference in blood flow velocity in central retinal artery and vein, posterior ciliary arteries and vortex veins between patients with Graves disease and the control group. The maximal blood flow velocity in superior orbital vein was significantly decreased (P = 0.01 on right eye, P = 0.04 on left eye). There was a slight correlation between reduced venous outflow in the superior orbital vein and the severity of the disease (r = 0.52 on right eye, r = 0.5 on left eye).
Conclusion: Color Doppler imaging is a new, noninvasive technique that could be used to examine patients with thyroid ophthalmopathy. Reduced venous outflow may contribute to exophthalmus by creating perivenous edema and consequent swelling of orbital fat.