Imaging the Orbit

Question 1

When do you use non-contrast CT scans for the eyes?

Answer 1

For suspected orbital trauma (acute)

Bleeds are really easy to pick up without contrast

Question 2

When do you use contrast CT scans for the eyes?

Answer 2

For most other suspected conditions that aren’t acute trauma

Question 3

4 things to exam in the orbit

Answer 3

Bones
Soft tissues (globe, lens, muscles)
Vessels
Nerves

Question 4

Orbit definition

Answer 4

The cavity or socket of the skull in which the eye and its associated soft tissue structures are situated

Question 5

The superior orbital fissure contains what 4 nerves?

Answer 5

CN 1, 4, 6, and 3

Question 6

Optic canal contains what 2 things

Answer 6

Optic nerve

Ophthalmic artery

Question 7

Inferior orbital foramen contains what what 3 things

Answer 7

CN V2
Pterygopalatine ganglion
Infraorbital artery/vein

Question 8

Does all pathology of the orbit require imaging?

Answer 8

No!

Clinical exam and patient history is usually sufficient

Question 9

Why is orbital imaging usually done?

Answer 9

To assess the extent of disease

Question 10

Extraconal space vs intraconal space

And which one is more serious

Answer 10

Extra: outside the orbital muscles
Intra: inside the orbital muscles (more serious)

Question 11

Orbital blowout fracture

Answer 11

Traumatic deformity of orbital floor or medial wall resulting from impact of blunt object larger than orbital aperture

Question 12

CT or MRI for

1. Soft tissues
2. Bones

Answer 12

1. MRI

2. CT