To the Editor.
—As magnetic resonance imaging (MRI) has become an increasingly useful and necessary adjunct to patient care, the potential problem of scanning patients with intraocular metal has been noted.1 The possible presence of minute quantities of ferromagnetic materials in retinal tacks, in view of the strength of the magnetic field produced, has led to concern. A general policy has been to exclude patients with retinal tacks from MRI scanning.One previous report, testing two types of retinal tacks, suggests that MRI may be safe.2 We know of at least seven varieties of tacks available at the Bascom Palmer Eye Institute, Miami, Fla, and have included them in a study exposing them to two magnetic sources: an electromagnet of approximately 0.1 T (Mueller Giant Eye Magnet, 115 V, 60 Hz, alternating current, V. Mueller and Co, Chicago, Ill), and a 1.5-T MRI system (Picker Vista, Cleveland, Ohio).