[Choice of neuroradiological methods in ophthalmology--the optic nerve, muscles of the eye and orbit].

Optimal imaging of the orbital structures presents a challenge. Images of this region may be disturbed by ocular movements, and orbital fat may prevent visualisation of the optic nerve and retrobulbar lesions. In this article, we intend to provide practical guidelines for the evaluation of orbital abnormalities, on the basis of our own experiences and a study of selected literature. Computed tomography (CT) and magnetic resonance imaging (MRI) are both useful for the detection and characterisation of orbital abnormality. However, for diagnostic work-up of the optic nerves, contrast-enhanced, fat-suppressed MRI best demonstrates the pattern and severity of optic nerve abnormality and allows assessment of the intracranial part of the optic nerves and associated intracranial abnormality. In the case of bony involvement, spiral CT imaging is the modality of choice. It is quick, inexpensive and allows multiplanar reconstruction. Not uncommonly, CT as well as MRI may be needed to characterise an orbital lesion.