Neuro and opthal OSCE examination

Question 1

full assessment of eye

Answer 1

• Visual acuity testing
• Near vision and colour vision
• Pupillary defects
• Visual fields and blind spot
• Extraocular testing (H)
• Slit lamp (fluoresceine stain and Mydriatics (tropicamide, atropine)
• Fundoscopy
• Optical coherence topography or US

Question 2

visual acuity testing uses

Answer 2

Snellens (6m)

Question 3

Visual acuity

Answer 3

• 6 metres (in exam will be given 3 metre chart- still use 6/6/ terminology)
• Ask if is she wearing glasses or contact lenses
  o If you see them with glasses on lap, ask them to put it on
• Do one eye at a time, covering the other eye
• If patient cant read a certain line add Pinhole (refracts light)

Question 4

snellen: If the patient cant see anything

Answer 4

• Try pinhole first
• If pinhole not working: reduce distance to 3m
• If 3m not close enough: go to 1m
• Use fingers at 50 cm (HM)
• Then move to 30cm etc
• Then move to wave
• Then move to light (on or off) (PL – perception of light)

Question 5

Near vision chart

Answer 5

• With reading glasses
• Test one eye at a time
• Ask them to read it where the patients usually reads comfortable
• Documentation: write the label for the size of the line

Question 6

colour vision

Answer 6

How to use Ishihara plates
If the patient normally wears glasses for reading, ensure these are worn for the assessment.

1. Ask the patient to cover one of their eyes.
2. Then ask the patient to read the numbers on the Ishihara plates. The first page is usually the ‘test plate’ which does not test colour vision and instead assesses contrast sensitivity. If the patient is unable to read the test plate, you should document this.
3. If the patient is able to read the test plate, you should move through all of the Ishihara plates, asking the patient to identify the number on each. Once the test is complete, you should document the number of plates the patient identified correctly, including the test plate (e.g. 13/13).
4. Repeat the assessment on the other eye.

Question 7

testing pupils involves

Answer 7

Direct and consensual
Swining light test: RAPD
Accomodation reflex

Question 8

general inspection and pupillary examination

Answer 8

Pupil size
Normal pupil size varies between individuals and depends on lighting conditions (i.e. smaller in bright light, larger in the dark).

Pupils can be smaller in infancy and larger in adolescence, then often smaller again in the elderly.

Pupil symmetry
Note any asymmetry in pupil size (anisocoria). This may be longstanding and physiological or be due to acquired pathology. If the difference in pupil size becomes greater in bright light such as when facing a window in daylight, this would suggest that the larger pupil is the pathological one. This is because the normal pupil will constrict in brighter light accentuating the difference in size. If the difference is more pronounced in dim lighting, this would imply the smaller pupil is abnormal as the larger pupil would then dilate while the pathologically small pupil remains the same size.

Examples of asymmetry include a larger pupil in oculomotor nerve palsy and a smaller one in Horner’s syndrome.

Pupil shape
Pupils should be round. Abnormal shapes can be congenital or due to pathology (e.g. posterior synechiae associated with uveitis) or previous trauma and surgery.

Peaked pupils in the context of trauma are suggestive of globe rupture (the peaked appearance is caused by the iris plugging the leak).

Pupil colour
Asymmetry in pupillary colour is most commonly due to congenital disease.

Question 9

direct and consensual

Answer 9

Shine onto the nasal retina (from an angle- less uncomfortable for patient)
- one eye at a time - look at both eyes to see constriction

Question 10

swinging light test (RAPD)

Answer 10

Move the pen torch rapidly between the two pupils to check for a relative afferent pupillary defect

Swing the light back-and-forth between the eyes. Normally, the pupil will constrict with one eye, dilate a little as the light passes over the nose, and constrict again with the other eye. Thus, you get constrict – constrict – constrict – constrict.

However, when one eye doesn’t see as well, the pupils don’t constrict quite as well. In fact, the pupils appear to dilate a little when you hop over to the bad eye with that flashlight. Thus, you get constrict – dilate – constrict – dilate.

Question 11

causes of RAPD

Answer 11

Relative afferent pupillary defect (Marcus-Gunn pupil)

Normally light shone into either eye should constrict both pupils equally (due to the dual efferent pathways described above). When the afferent limb in one of the optic nerves is damaged, partially or completely, both pupils will constrict less when light is shone into the affected eye compared to the healthy eye. The pupils, therefore, appear to relatively dilate when swinging the torch from the healthy to the affected eye. This is termed a relative…. afferent… pupillary defect. This can be due to significant retinal damage in the affected eye secondary to central retinal artery or vein occlusion and large retinal detachment; or due to significant optic neuropathy such as optic neuritis, unilateral advanced glaucoma, compression secondary to tumour or abscess and ischaemic optic neuropat

retinal artery occlusion
optic neuritis (MS, syphillis, sarcoidosis)
retinal detachment

Question 12

Accommodation reflex

Answer 12

1. Ask the patient to focus on a distant object (clock on the wall/light switch).
2. Place your finger approximately 20-30cm in front of their eyes (alternatively, use the patient’s own thumb).
3. Ask the patient to switch from looking at the distant object to the nearby finger/thumb.
4. Observe the pupils, you should see constriction and convergence bilaterally.

Question 13

what actually occurs in accomodation reflex

Answer 13

It is dependent on cranial nerve II (afferent limb of reflex), superior centers (interneuron) and cranial nerve III (efferent limb of reflex)

• Edwinger westphal nucleus (parasympathetic)

Features

• Pupil constriction
• Lens accommodation (bi-convex) - ciliary muscles contract, causing increased refractive power
• Convergence.

Question 14

visual field testing

Answer 14

• Using neurotip (white and red)
  o Bright room – red tip
  o Dark room- white tip
• Only show top of neurotip
• Test one eye at a time
  o Horizontal
  o Quadrants
• Cover same eye as patient
• Ask patient to look at neurotip so they recognise it
• Test visual field against your own in the pattern of the the pictures above
• Switch arms when testing the nasal visual fields

Question 15

Blind spot

Answer 15

• Cover same eye a each other
• Ask patient to look in your eye
• Take it from the midline laterally and back
  o Do horizonal then vertical once found
• Should both have similar blindspot

Question 16

fundoscopy basics

Answer 16

If eye not dilated use smaller white light. If dilated use big light
Set up the ophthalmoscope as you need it

• Use your right eye for their right eye
• Use their left eye for their left eye
• May use both eyes or cover one eye
• Ask their prescription , may need to change numbers on dial
• Ask patient to look into distance to prevent pupil constriction

Question 17

fundoscopy and red reflex

Answer 17

1) Start a distance away till you see a red reflex (can put hand on forehead) at 45 degree angle
2) Red reflex will start to clear as you get closer, use the red reflex as the key into the eye
3) Then as you get closer you will start to see vessels
4) Follow vessel on the fundus and follow to find a branch (will look like an arrow) – will point towards the optic disc
5) Then ask patient to look at light directly to look at macula (will be more ucomfortable)

Assess

• optic nerve
• retina
• macula

Question 18

cover tests

Answer 18

Question 19

Preparation for fundoscopy

Answer 19

1. It is essential to darken the room for the examination. Make sure the patient is positioned seated prior to turning out the lights to avoid accidents.
2. Dilate the patient’s pupils using short-acting mydriatic eye drops such as tropicamide 1%. You will be unable to monitor pupil reactions once dilating drops have been applied, furthermore assessing vision, colour vision, double vision and visual fields will be less accurate once drops are instilled.
3. Ask the patient to look straight ahead for the duration of the examination (asking the patient to fixate on a distant target such as a light switch can cause confusion if you then obstruct the view of this target).

Question 20

Causes of an absent fundal (red) reflex

Answer 20

Absence of the fundal reflex in adults is often due to cataracts in the patient’s lens blocking the light. Other causes include vitreous haemorrhage and retinal detachment.

Absence of the fundal reflex in children can be due to congenital cataracts, retinal detachment, vitreous haemorrhage and retinoblastoma.

Question 21

extraocular eye testing

Answer 21