Week 1 - Neuro 1.1 Flashcards
What is the definition of Neuro-ophthalmology?
The branch of medical science dealing with the relationship of the eyes to the central nervous system.
What are some Symptoms and Signs in neuro-opthalmology?
- Decreased vision
- Double Vision
- Transient visual loss
- illusions/ hallucinations
- nystagmus
- Pain
- Headache
- Ocular motility problems
- pupillary abnormalities
- eyelid/facial/head abnormalities
- Higher cortical function
- ataxia/hemiparesis/hemisensory weakness
What are the 3 important points you should focus on when the Px has a history of reduced vision?
• Associated symptoms
• Unilateral/bilateral
• Time course
What do Unilateral vs bilateral differences indicate?
• Unilateral: lesion anterior to chaism
• Bilateral: either bilateral optic nerve or retinal, chiasmal or retrochiasmal disease
• Specific reference to homonymous hemianopia: often regarded by patients as monocular involvement on side of affected hemifield
Time course rules of thumb:
• Minutes: ischaemic retinal event
• Hours: most commonly ischaemic, more likely optic nerve
• Days-weeks: more frequently inflammation (may reflect ischaemia)
• Months-years: compressive
• There could be overlap
• Patients can become suddenly aware of a chronic problem when fellow eye covered
What 6 techniques/tests are done for a neuro examination?
• Best corrected visual acuity
• Pupillary testing
• Fundus examination
• Visual field testing
• Colour vision
• Contrast sensitivity
What are the two pupillary pathways?
• Sympathetic innervation (dilator pupillae)
• Parasympathetic innervation (sphincter)
What is the sympathetic innervation pathway?
From eye to brain:
• Short ciliary nerves > Ciliary ganglion > Edinger westphal nucleus > inhibitory sympathetic pathway > hypothalmic center
From brain back to eye:
• Ciliospinal center> inferior cervical ganglion > (C8 and T1) superior cervical ganglion> Long ciliary nerve
What is the parasympathetic innervation pathway?
• Afferent and Efferent pathways
- Afferent : Eye > optic chiasm > branches to right/left pretectal nuclei
- Efferent : Prelectal nuclei > edinger-westphal nucleus > 3rd nerve > ciliary ganglion > short ciliary nerves > sphincter
When doing pupillary testing, what is observed and what is Anisocoria?
- Observe size, shape and asymmetry of pupils A distant, non-accommodative target in dim light
• Anisocoria
- Diff. of >0.4mm is anisocoria
- 25% of Normals have this in dim light, 10% in room light
What can differences in pupil size indicate : examples?
• If anisocoria is present, measure pupil sizes in dim and bright light
• Difference remains constant: likely to he normal
• Difference largest in dim light: possibly normal; possibly problem with dilation of smaller pupil
• Difference largest in bright light:possibly problem with constriction of larger pupil
What 4 things are tested with pupils?
- Observe size, shape and asymmetry of pupils
- Check for direct and consensual reflexes
- Swinging flashlight test (check for RAPD)
- Check for near reflex
How is “checking for direct and consensual reflexes” done?
• Shine pen torch onto RE, observe R pupil reaction, remove - R direct
• Shine pen torch onto RE, observe L pupil reaction, remove - L consensual
• Shine pen torch onto LE, observe L pupil reaction, remove - L direct
• Shine pen torch onto LE, observe R pupil reaction, remove - R consensual
How and why is the swinging flashlight test done?
• To check for relative afferent pupillary defect (RAPD)
- Shine light into one eye, observe direct and consensual response After 2-3 seconds, QUICKLY swap the light to the other eye, looking for any change in pupil size of this eye
- After 2-3 seconds, QUICKLY swap the light to the first eye, looking for any change in pupil size of this eye
How is checking for near reflex done?
• Look at distant, non-accommodative target
• Look at near, accommodative target
What is a RAPD and what are the 3 responses to a swinging flashlight test?
RAPD
• Impaired optic nerve function
• Gross retinal abnormality (VA 6/60 or worse), in one eye or asymmetric
• Asymmetric chiasmal compression
• 3 types of response:
• Pupil stays constricted (normal) = no RAPD
• Pupils dilate fully = total RAPD
• Pupils dilate a little bit and slowly; sluggish response = partial
RAPD
Why is visual fields measured from a neuro perspective with and how is choice selection selected?
• Supplements acuity in assessing visual loss
• Helps localise lesion along afferent visual pathway
• Quantifies defect and assesses change over time
Choice of field testing:
- Degree of detail required
- Patient’s ability to co-operate
• Confrontational, Amsler, Perimetry
What and why do certain colour vision defects occur?
• Optic neuropathies manifest red-green defects
• Red desaturation, “maroon”
• Optic nerve: dyschromatopsia > visual acuity loss
• Macula: dyschromatopsia = visual acuity loss
• Persisting defect even after visual recovery
Why and how is contrast sensitivity measured?
• Visual acuity tested at a high level of contrast
• Contrast sensitivity more sensitive
• Useful in detection and quantitation of visual loss in presence of normal visual acuity
Examples:
• Grating tests - Vistech
- Difficulty to administer and reliably reproduce
• Pelli-Robson
- Single size optotype with gradually diminishing contrast level
What are the definitions of Optic: neuropathy, atrophy, oedema and neuritis (and the type behind optic nerve head?)
• Optic Neuropathy = disease/dysfunction of one or more peripheral nerves. Damage to the optic nerve due to any cause. Both swelling and atrophy give signs of optic neuropathy.
• Optic atrophy: Atrophy = wasting away
• Optic oedema: edema = swelling
• Optic neuritis: ‘itis’ = inflammation
- Kanski: inflammation, infection or demyelinating process of the optic
nerve
- Retrobulbar neuritis = behind the optic nerve head
What is the definition of optic neuropathy?
Neuropathy = disease or dysfunction of one or more peripheral nerves
Damage to the optic nerve due to any cause
Both swelling and atrophy give signs of optic neuropathy
