A patient presented with unilateral proptosis which was compressible and increases on bending forward. On examination no thrill or bruit was present. MRI done showed a retro orbital mass with enhancement. What is the MOST likely diagnosis?

On the basis of the presentation and MRI patient is most likely suffering from orbital varix. Orbital varix is associated with a variable exophthalmos that changes with body position or with variations in intrathoracic pressure and has no audible bruit. The varix can be variably positioned deep within the orbit or in the subcutaneous tissues anterior to the orbital septum. A varix can be identified by using Valsalva maneuver, ultrasonography, CT scanning or MRI. Treatment of this condition is usually not necessary. Surgical decompression is indicated only in cases of ocular or neural compression by acute hemorrhage. Ref: Clinical Neuro-Ophthalmology: A Practical Guide edited by Ulrich Schiefer page 135.