Fig. 12. Orbital venous flow malformation. This 77-year-old woman presented with a 10-year history of left enophthalmos. A. and B. Hertel measurements were 12 mm on the right and 8 mm on the left at a base of 96. With Valsalva maneuver the patient demonstrated 4 mm of proptosis on the left side. C. and D. This proptosis resolved 10 to 15 seconds after the Valsalva maneuver ended. (Courtesy of Dr. John V. Linberg, University of West Virginia, Morgantown, WV)