neurology

Question 1

causes of optic atrophy

Answer 1

• Demyelination
• Trauma
• Compression eg pituitary tumour or meningioma
• Diabetes
• Toxic eg methanol
• Secondary to papilloedema

Question 2

signs of optic atrophy

Answer 2

Optic neuropathy: signs 
• Pale disc 
• Loss of visual acuity 
• Loss of red colour vision 
• Central scotoma 
• Afferent pupillary defect (the Marcus Gunn pupil)

Question 3

explain optic neuritis in demyelinating disease

Answer 3

With demyelinating disease, optic neuropathy is a relatively common presentation. The eye is
often painful and the patient complains of blurred vision in the affected eye, particularly
centrally- “like looking through the bottom of a beer glass”. Red colour vision is lost early- so
the world looks bluer through the affected eye. About 80% have retrobulbar neuritis- where
initial examination of the fundus is normal. The remaining 20% have a demyelinating plaque
right at the front of the optic nerve: this gives the appearance of papilloedema. After about 6
weeks, patients will have recovered most, but not all, of their vision and fundoscopy will then
reveal a pale disc- optic atrophy. Sometimes this is called primary optic atrophy- due to a
primary problem with the nerve, rather than secondary to papilloedema or tertiary, in
association with disease of the retina.