CT and MRI of the eye and orbit

Advances in cross sectional imaging methods such as ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) have greatly contributed to the understanding and diagnosis of intraocular and retrobulbar diseases. While ultrasound is an excellent method for assessing the intraocular structure it is less capable to fully assess the retrobulbar space due to the osseous boundaries that absorb the ultrasound beam and cannot be penetrated. The intracranial portion of the optic nerve and the optic chiasm are therefore only accessible with CT and MR imaging. Both methods have their advantages and disadvantages that will be discussed in the following. Understanding the basic principles of CT and MR imaging helps with the deciding which modality would provide the best information on any given patient, and will aid in interpretation of the acquired study.