Magnetic resonance imaging in patients implanted with Ex-PRESS stainless steel glaucoma drainage microdevice.

PURPOSE

To evaluate whether artifacts caused by a stainless steel glaucoma drainage device can alter the interpretation of magnetic resonance imaging (MRI) scans of the optic nerve and brain.

DESIGN

Consecutive case series.

METHODS

Five patients (7 eyes) with Ex-PRESS devices (Optonol Ltd, Neve Ilan, Israel) positioned at the limbus were studied. For each subject, an axial T1-weighted, axial and coronal T2-weighted with fat saturation, and whole brain proton density (PD)/T2-weighted MRI scan was obtained. Standard MRI protocol was not optimized for the imaging of patients harboring Ex-PRESS implants. The effects of the device on PD/T2 pulse sequence imaging of the optic nerve and brain were rated from 1 (optic nerve margins unidentifiable or brain details altered) to 5 (excellent visualization of the optic nerve and brain).

RESULTS

For optic nerve visualization, 1 optic nerve scored 2, 3 optic nerves scored 3, and 3 optic nerves scored 4 (mean, 3.3 +/- 0.8 standard deviation). For whole brain imaging, 4 patients scored 4 and 1 patient scored 5 (mean, 4.2 +/- 0.4 standard deviation).

CONCLUSIONS

Our data demonstrate that interpretation of MRI scans of the orbit and brain is unaffected by the artifacts caused by the Ex-PRESS shunt, whereas optic nerve imaging may be affected. We are unaware of previous reports of this finding and could find no reference to it in a computerized search using PubMed.