Colour Doppler imaging of superior ophthalmic vein in thyroid-associated eye disease

One of the possible etiologies of proptosis in patients with thyroid-associated eye disease is stated to be passive orbital venous congestion caused by the occlusive and constrictive changes of the superior ophthalmic vein (SOV). In an attempt to clarify the validity of this claim, quantitative information on the flow velocity of the SOV was obtained by colour Doppler imaging in 24 patients with thyroid-associated eye disease and compared with data from the control group.

On clinical examination, ocular motility, proptosis, soft tissue involvement, and the presence of optic neuropathy were evaluated. The interaction of these signs with the flow velocity of the SOV was investigated in conjunction with computed tomographic (CT) findings such as extraocular muscle enlargement, dilatation of the SOV, and apical crowding of the orbit.

The mean blood flow velocity was significantly decreased in patients compared to the control group (P <.05). The CT measures that contributed to significant decreases in SOV blood flow velocity were apical crowding (P <.05) and the coexistence of horizontal and vertical extraocular muscle involvement (P <.05). Among the clinical measures, significant decreases could be attributed to soft tissue findings (P <.01) and to optic neuropathy (P <.05).

External compression of the SOV may contribute to the SOV blood flow decrease in orbits afflicted with thyroid eye disease, but proptosis is not relevant to the SOV blood flow decrease.