Optic Nerve Flashcards
The axons leave the eyeball through the?
Lamina crirosa sclerae
How does the optic nerve differe from all the other nerves?
It is not a peripheral nerve but rather a central nervous system tract and it has no ability to regenerate if it is damaged
What makes up the retrobulbar part of the optic nerve?
- The intra-orbital
- Intracanalicular
- Intra-cranial
What is theocular part made of?
The optic disk
What makes the retro-bulbar relatively resistant to ocular occlusion?
There is a complex anastomosis of various branches of the internal carotid artery
Why is the optic disk prone to vascular occlusion?
Because it has short posterior ciliary branches of the internal cariotid artery
What are the symptoms of optic nerve disease?
- Loss of vision
- Retrobulbar pain occurs only in optic neuritis
What are the signs of optic nerve damage?
- Decreased VA
- Decreased VF
- Pupil:sluggish reaction to light
- Disc appearance may appear swollen because of raised intracranial pressure
- or pale due to optic atrophy
What are the 4 characteristics of the optic disc that we must always assess on opthalmoscopy?
- The margin/contour and whether it is well defined
- The colour which is usually pink
- The cup or C/D ratio
- The blood vessels or venous pulsation to ensure that there is not cental retinal venous occlusion
What does this image depict?
Name 7 characteristics that is the classical appearance of optic swelling?
- Disc hyperaemia and dilated capillaries on the disc
- The disc margin/contour is indistinct
- Disc and retinal venous congestion
- Loss of retinal venous pulsation
- Cotton wool spots on and around the disc
- Hard exudates around the disc
- Nerve fibre layer haemorrhages on and around the disc
What are the two exceptions to the classical appearance
- Anterior IschaemicOptic Neuropathy
- Central Retinal Venous Occlusion
What are transient obscurations of vision?
Multiple episodes of blurred vision each which last for only a few seconds
Is optic disc swelling unilateral or bilateral?
It is usually bilateral and symmetrical
What is the Foster-Kennedy syndrome?
A condition causing unilateral optic disk swelling in raised intracranial pressure