MR imaging features of giant reservoir formation in the orbit: an unusual complication of Ahmed glaucoma valve implantation.

We report the MR imaging findings of an unusually large fluid collection, so-called giant reservoir, around an Ahmed glaucoma valve implant that caused progressive proptosis in a patient with posttraumatic glaucoma. Although other cystic lesions of the juxtalacrimal area of the orbit, such as dermoid cyst, can present similar imaging findings, the characteristic morphology and location should lead the radiologist to the correct nature of this cystic lesion.