Ex-PRESS glaucoma filter: an MRI compatible metallic orbital foreign body imaged at 1.5 and 3 T

•The Ex-PRESS glaucoma filtration device is a tiny metallic orbital implant.•It can simulate a metallic orbital foreign body on imaging.•There is little information in the literature about it's MRI safety.•We report 18 MRIs performed on 7 patients including the first at 3 T.•Imaging appears to be safe at 1.5 and 3 T in patients with this device.

AimTo report on the MRI compatibility of the Ex-PRESS glaucoma filtration device, a tiny metallic implant placed into the anterior chamber of the eye that is much smaller than traditional glaucoma shunts, and to educate the radiology community regarding its appearance.Materials and methodsSeven patients with Ex-PRESS glaucoma filtration devices were identified that had undergone MRI at San Francisco General Hospital/University of California San Francisco Medical Center by searching and cross-referencing the radiology reporting system and the electronic medical record. MRI images were reviewed for artefact interfering with interpretation. Ophthalmology examinations were reviewed for evidence of complications.ResultsEighteen individual MRI examinations were performed during 12 unique MRI events on these 7 patients. 13/18 individual MRI examinations and 7/12 MRI events were performed at 3 T with the others performed at 1.5 T. Mean time from Ex-PRESS implantation to MRI was 17.5 months. Mean time from MRI to first ophthalmology examination was 1.1 months and from MRI to latest ophthalmology examination was 6.6 months. Susceptibility artefact did not interfere with image interpretation and no complications related to MRI were encountered.ConclusionThe Ex-PRESS glaucoma filtration device appears to be safe for MRI at 1.5 and 3 T and does not produce significant susceptibility artefact to affect diagnostic interpretation adversely.