JUN 01, 2009
The authors of this study obtained and examined magnetic resonance images using a 3-Tesla MRI of five patients (seven eyes) who had undergone implantation with the Ex-PRESS miniature shunt. The Ex-PRESS shunt is a miniature stainless steel glaucoma device that is inserted to create an ostium during trabeculectomy. Since the shunt is made of stainless steel, ophthalmologists have been concerned that imaging artifacts during MRI of the optic nerve, orbit and brain may occur in individuals implanted with the device. However, the FDA has deemed magnetic resonance imaging safe in patients using the device.
The authors quantified visualization of the orbit, optic nerve and brain in the study's subjects. Optic nerve visualization was judged to be of sufficient quality on average (3.3 out of 5) and whole brain imaging of good quality (4.2 out of 5). The data suggested that images of the brain and orbit were minimally affected by artifacts caused by the device. However, optic nerve imaging quality was decreased.
This information is important for clinicians and radiologists caring for patients with glaucoma who might need to undergo imaging studies in the future. Some of the optic nerve effects might be minimized by using pulse sequence optimization.
Dr. Edward is a consultant to Alcon Laboratories, Inc., and Allergan, Inc. He receives lecture fees from Alcon Laboratories and Allergan and grant support from Alcon Laboratories and Pfizer Ophthalmics.