Orbital CT is a targeted scan of the eye sockets: mainly their bony walls, but also the eyeball, eye muscles, optic nerve and lacrimal glands. It is most often ordered after an injury or when a tumour is suspected.
- Duration5 min; with contrast 20–30 min
- Contrastif indicated
- Preparationnone (fasting if contrast is used)
- Report30 min – 1 hour
What it shows
- Fractures of the orbital walls, bleeding into the orbit
- Metal foreign bodies
- Benign and malignant tumours of the eyeball and orbital walls, spread of tumours from the nasal sinuses
- Thyroid (autoimmune) eye disease, thickened eye muscles
- Inflammatory infiltrates in the orbit
- Changes of the optic nerve
- Lacrimal gland disease
When it is recommended
- Facial or head injury with a suspected orbital fracture or eyeball contusion
- Suspected foreign body in the orbit
- Eye pain, sudden loss of vision, or bulging eyes (exophthalmos) of unclear cause
- Paralysis of the eye muscles
- Suspected orbital tumour, assessing its spread
- Eye examinations that have not given enough information
- Contraindications to MRI
Preparation
- If contrast is planned, come on an empty stomach.
Good to know
- No contrast is needed for a suspected fracture; to tell a benign from a malignant tumour, the scan is usually done with contrast.
- 3D reconstruction of the images is available and helps clarify the injury.
- MRI shows the eyeball and muscles in more detail, while CT is best for bone; with a metal foreign body MRI is contraindicated, so CT is used.
General information about CT — safety, contraindications, contrast and what to expect — is on the CT page.