Magnetic resonance imaging is a non-invasive technique that uses strong magnetic fields and radio waves to produce detailed cross-sectional images of soft tissues, including the brain, orbits, and optic nerves. It does not involve ionising radiation.
Technique
The patient lies within a scanner while sequences are acquired that highlight different tissue characteristics. Contrast agents may be injected intravenously to enhance certain structures or lesions.
- Provides excellent soft tissue contrast for brain and orbital structures
- Multiplanar views show the course of the optic nerves and chiasm
- Specialised sequences can assess blood vessels or inflammation
- Contraindications include some metallic implants and severe claustrophobia
Ophthalmic Applications
MRI is widely used to investigate optic neuropathies, orbital tumours, demyelinating disease, and unexplained visual field defects. Findings guide diagnosis, prognosis, and treatment planning.
- Helps differentiate compressive from inflammatory or ischaemic lesions
- Useful in assessing pituitary and chiasmal pathology affecting vision
- Serial scans monitor progression or response to therapy
- Results are interpreted with clinical examination and visual function tests
