Distensible Venous Malformation
Distensible venous malformations of the orbit, previously known as orbital varices, are low-flow lesions that enlarge with a Valsalva maneuver. Patients may exhibit enophthalmos at rest, when the lesion is not engorged. Proptosis that increases when the patient’s head is dependent or after a Valsalva maneuver suggests the presence of a venous malformation (Fig 5-3A, C). Apart from the inducible proptosis, the ophthalmic examination is often unremarkable, with symmetric intraocular pressures (IOPs), lack of conjunctival vessel engorgement, and no reflux of blood in the Schlemm canal. The diagnosis can be confirmed with imaging such as MRI (Fig 5-3D) or contrast-enhanced rapid spiral computed tomography (CT) during a Valsalva maneuver or other means of decreasing venous return; cases show characteristic enlargement of the engorged veins. Phleboliths may be present on imaging.
Figure 5-3 Distensible venous malformation. A, Mild proptosis resulting from venous malformation of the right orbit. B, Fullness of the right superior orbit (arrow). Note the absence of dilated corkscrew conjunctival vessels. C, After Valsalva maneuver, proptosis of the right globe increases (arrow).D, T1-weighted axial MRI shows a venous malformation of the superior ophthalmic vein.
(Courtesy of Bobby S. Korn, MD, PhD.)
Management is usually conservative, with observation of relatively asymptomatic lesions. Biopsy should be avoided because of the risk of hemorrhage. Surgery is reserved for patients who have significant pain or in whom the malformation causes vision-threatening compressive optic neuropathy. Complete surgical excision is difficult, as these lesions often intertwine with normal orbital structures and directly communicate with the abundant venous reservoir in the cavernous sinus. Treatment of highly symptomatic lesions typically consists of combined embolization and excision. Sclerosants, injected either percutaneously or directly through an open approach, are an additional treatment option. However, orbital compartment syndrome may occur, requiring urgent decompression.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.