Neuro Ophthalmology Flashcards
(139 cards)
What are the 2 different visual pathways controlling pupil reactions?
Sympathetic- Dilator
Parasympathetic- sphincter
When is the pupil at its max dilation and minimum constriction?
Dilation- apprehensive in the dark
Constriction- bored while sunbathing
What is the primary driver of pupil light responses?
Parasympathetic pathway
What is the process from afferent to efferent response?
The afferent section allows RGCs light signals to reach midbrain (Edingerwest phal nucleus). This is responsible for generating afferent to efferent constriction signal.
What does the sympathetic pathway contributes to?
Light response via activation of dilatory muscle
Where does the sympathetic pathways passes over in the body?
Sites that exposes nerve fibre to local and systemic diseases i.e. lung tumours and internal carotid artery
What conditions do not give rise to an RAPD?
- Cataracts
- Amblyopia
- Visual pathway lesions post to Chiasm
When is it an exception for a post to the chiam lesionto cause an RAPD?
If more in 1 eye than the other, INCONGROUS homo hemiamopia or quadrantanopia
When is an RAPD caused?
If there is an imbalance in strengths of right and left afferent signals
What conditions that are associated with RAPD?
- Anterior Ischaemic Optic Neuropathies (Arteritic or non Arteritic?
- Optic Neurits
- Advanced glaucoma
- Unil ON tumour
- Tumours compressing ON
- Unil ON Trauma
- Orbital disease
What are key signs for an RAPD to be present?
Unilateral and Aysmmetric VF defects
Also depends on degree and depth/extent
Which area is effected to cause AION or NA AION?
Short posterior ciliary arteries
What tumours may cause an RAPD?
Meninginoma, pituitary lesion, ON glioma
What are the conditions that show a normal reacting pupil?
- Physiological anisocoria
2. Horners syndrome
What are the conditions that show an abnormal reacting anisocoia?
- Adies tonic pupil
2. 3rd nerve palsy
What are the signs of a physiological anisocoria and how common is it?
15-20% of the population Asymptomatic
Normal vision
No GH association
No ptosis
Which pathway is effected in horners syndrome?
Sympathetic pathway
What are the causes of horners syndrome?
- Brainstem damage
- Carotid or Aorotic artery dissection
- ‘Pancoast tumour’ (Apical lung tumour)
Where are the potential pathologys located to cause horners syndrome?
- Sup cervical symp ganglion
- Internal carotid artery
- Long ciliary nerve
- Ciliary ganglion
What symptoms are likely to be seen in an carotid artery dissection?
HAs Numbness/weakness Neck and shoulder pain (If ophthalmic artery effected- Amarausis fugax) Painful acute horners syndrome
What is a carotid artery dissection?
A tear in the internal artery wall
What are the ocular signs of horners syndrome?
- Miosis
- Ptosis
- Anhidrosis
Which muscle has reduced innervation in ptosis?
Superior or inferior tarsal muscles
If both upper and lower tarsal muscles were seen to have reduced innervation, what may this be misdiagnosed as?
Endophthalmos