1
Q
what equipment is required for the cranial nerves examination?
A
- pen torch
- Snellen chart
- Ischihara plates
- opthalmoscope and mydriatic eye drops
- cotton wool
- neurotip
- tuning fork (512Hz)
- glass of water
2
Q
what is looked for in general inspection?
A
- speech abnormalities
- facial asymmetry
- eyelid abnormalities
- pupillary abnormalities
- strabismus
- limbs
- walking aids
- hearing aids
- visual aids
- prescriptions
3
Q
how is the olfactory nerve (CN I) tested?
A
- ask patient if they have noticed any recent changes to their sense of smell
- can be tested more formally using different odours (e.g. lemon or peppermint) or using the University of Pennsylvania smell identification test
4
Q
what are some causes of anosmia?
A
- mucous blockage of the nose
- head trauma
- genetics
- Parkinson’s disease
5
Q
how is the optic nerve (CN II) tested?
A
- assess pupil size
- assess pupil shape
- assess pupil symmetry
- assess and record visual acuity
- direct pupillary reflex
- consensual pupillary reflex
- swinging light test
- accommodation reflex
- Ischihara plates
- visual neglect/inattention
- visual field assessment
- blind spot assessment
- fundoscopy
6
Q
how is visual acuity assessed?
A
- use a Snellen chart
- if patient usually uses distance glasses, ensure they’re worn
- ask patient to cover one eye and read the lowest line they’re able to
- record the lowest line the patient was able to read (e.g. 6/6 (metric) is equivalent to 20/20 (imperial))
- you can have the patient read through a pinhole to see if this improves vision
- repeat with other eye
7
Q
how is visual acuity recorded?
A
- chart distance in metres (numerator) over the number of the lowest line read (denominator)
- if patient reads the 6/6 line but gets 2 letters incorrect, you would record it as 6/6 (-2)
- if patient gets more than 2 letters wrong, the previous line should be recorded as their acuity
- when recording the vision state whether this vision was unaided (UA), with glasses or with a pinhole (PH)
8
Q
what are further steps for patients with poor vision in visual acuity?
A
- reduce the distance to 3 metres from chart (3/denominator)
- reduce the distance to 1 metre from chart (1/denominator)
- assess if they can count the number of fingers you’re holding up (CF)
- assess if they can see gross hand movements (HM)
- assess if they can detect light from a pen torch shone into each eye (PL or NPL; perception of light)
9
Q
what are causes of decreased visual acuity?
A
- refractive errors
- amblyopia
- ocular media opacities e.g. cataract or corneal scarring
- retinal diseases such as age-related macular degeneration
- optic nerve pathology e.g. optic neuritis
- lesions higher in the visual pathways
10
Q
how is the direct pupillary reflex tested?
A
- dim lights and shine the light from the pen torch into their pupil and observe for pupillary restriction in the ipsilateral eye
- a normal direct pupillary reflex involves constriction of the pupil that the light is being shone into
11
Q
how is the consensual pupillary reflex tested?
A
- dim lights and shine the light from the pen torch into their same pupil, but this time observe for pupillary restriction in the contralateral eye
- a normal consensual pupillary reflex involves the contralateral pupil constricting as a response to light entering the eye being tested
12
Q
how is the swinging light test performed?
A
move the pen torch rapidly between the two pupils to check for a relative afferent pupillary defect
13
Q
how is the accommodation reflex tested?
A
- ask patient to focus on a distant object
- place your finger 20-30cm in front of their eyes
- ask patient to switch from looking at the distant object to the nearby finger/thumb
- observe the pupils, you should see constriction and convergence bilaterally
14
Q
how can you use the Ishihara plates to test colour vision?
A
- ask patient to cover one of their eyes
- ask patient to read the numbers on the Ishihara plates; the first page does not test colour vision and assesses contrast sensitivity
- if patient can read the test plate, move through all the plates, asking patient to identify the number on each
- once complete, document the number of plates identified correctly, including the test plate
- repeat on other eye
15
Q
what are some causes of colour vision deficiencies?
A
- optic neuritis
- vitamin A deficiency
- chronic solvent exposure
