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Inferior ophthalmic vein

The inferior ophthalmic vein is an important vascular structure within the orbit, responsible for draining venous blood from the lower parts of the orbit. It courses along the floor and medial wall of the orbit, ultimately draining into the cavernous sinus or pterygoid plexus. Its anatomical and imaging features are essential knowledge for radiologists, ophthalmologists, and surgeons dealing with orbital and cranial pathology.

Synonyms

  • Vena ophthalmica inferior

  • Inferior orbital vein

Function

  • Drains venous blood from the lower and medial portions of the orbit.

  • Collects blood from structures including the inferior rectus, inferior oblique muscles, lacrimal sac, and eyelids.

  • Contributes to the venous outflow of the eye and supports orbital drainage to the cavernous sinus or pterygoid venous plexus.

MRI Appearance

  • T1-Weighted Imaging:

    • Appears as a flow void (signal loss) due to fast-flowing blood.

    • Surrounding soft tissues display intermediate to high signal, highlighting the vein as a dark linear structure.

  • T2-Weighted Imaging:

    • Also seen as a flow void, similar to T1, unless blood flow is slow or thrombosed, in which case it may become hyperintense (bright).

    • Thrombosed inferior ophthalmic vein appears hyperintense (bright) on T2.

  • STIR (Short Tau Inversion Recovery):

    • Vein itself usually presents as a flow void (dark), but surrounding orbital edema or inflammation will be highlighted with high signal intensity.

    • Thrombosis or abnormal content within the vein may result in increased signal (hyperintensity) on STIR images.

CT Appearance

  • Non-contrast CT:

    • The inferior ophthalmic vein may not always be visible unless it is enlarged, thrombosed, or there is adjacent pathology.

    • Normally seen as a small, thin linear or tubular structure along the inferior and medial orbital wall.

  • Contrast-enhanced CT:

    • Vein enhances with intravenous contrast, becoming more conspicuous as a linear or curvilinear enhancing structure in the orbit’s inferior aspect.

MRI images

Inferior ophthalmic vein MRI coronal image