Ocular anatomy and cross-sectional imaging of the eye

Ocular cross-sectional imaging is usually obtained as an adjunct to clinical ophthalmologic examination and ocular ultrasound. Computed tomography/magnetic resonance imaging (CT/MRI) are complimentary for ocular imaging and are performed for evaluation of the vitreous cavity, choroid, retina, sclera, and potential spaces and for the assessment of extension of disease beyond the globe into the orbit or brain. CT has superior spatial resolution aided by the natural contrast between bone, soft tissues, air, and fat. The short scanning time is advantageous to reduce motion effects and the need for sedation. CT is also the modality of choice for evaluation of traumatic injury and for visualization of foreign bodies. Potential clinical indications for MRI include staging of retinoblastoma and other causes of leukocoria, assessment of retinal or choroidal detachments for underlying retinal mass or hemorrhage, uveal melanoma, ocular metastases, choroidal hemangioma, and buphthalmus, staphyloma, and coloboma. Last, but not least, MRI has the advantage of no ionizing radiation.