Secondary studies that are performed for specific indications include venography, arteriography, and stereotactic navigation. Although these studies are rarely used, they may be helpful in specific cases.
Before the advent of CT and MRI, orbital venography was used in the diagnosis and management of orbital varices and in the study of the cavernous sinus. Contrast material is injected into the frontal or the angular vein to reveal a venous abnormality. Subtraction and magnification techniques have been used to increase the resolution of venography. Because moving blood generates a signal void during MR imaging, larger venous abnormalities and structures can be visualized well on MR venography. Some orbitocranial vascular malformations or fistulas are best accessed directly via the superior ophthalmic vein, both for diagnosis and for possible treatment.
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.