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Visual system examination

Introduction  

  • Wash hands
  • Introduce self
  • Ask Patient’s name, DOB and what they like to be called
  • Explain examination and obtain consent

Inspection

  • Patient: well/unwell, posture etc.
  • Around bed: mobility aids, glasses
  • Eyes inspection:
    • Pupil size and symmetry
      • Unilateral dilated pupil (mydriatic eye drops, CN3 lesion, Holmes-Adie pupil, acute glaucoma, trauma)
      • Unilateral constricted pupil (miotic eye drops, Horner’s syndrome)
    • Strabismus (CN3 lesion = pupil ‘down and out’; CN6 lesion = cannot look laterally)
    • Ptosis (unilateral = CN3 lesion, Horner’s syndrome; bilateral = myasthenia gravis, myotonic dystrophy)
    • Proptosis (thyrotoxicosis, retro-orbital tumour)
    • Sclera (erythema, lesions)
    • Around eyes (scarring, lesions, pus, discharge, swelling)

Acuity

Ask the patient to cover one eye with their palm to test each eye in turn.

Distant vision (visual acuity)

  • Test with Snellen chart (the result is recorded as distance/smallest font size read, e.g. 6/9) 
  • If the patient wears glasses, do this with glasses on (corrected visual acuity) and off (uncorrected visual acuity)
  • A standard Snellen chart is read from 6 metres away but there are smaller versions which may be used at closer distances (e.g. 1 or 3 metres) – adjust the final acuity to ‘1/…’ or ‘3/…’ respectively
  • If the patient gets more than two letters wrong, the previous line should be recorded as their acuity. If they get two letters wrong, record acuity as the font size of this line but note ‘-2’ in brackets, e.g. 6/9 (-2); and if they get one letter wrong, note ‘-1’ e.g. 6/9 (-1).

Near vision

  • Read a line of a letter/magazine

Colour vision

  • ‘I would also like to test colour vision using Ishihara plates.’

Fields

Sit the patient 1 metre directly in front of you with both your eyes at the same level.

Visual inattention

  • While the patient keeps both eyes open and focussed on you, hold out your hands in each of their outer visual fields
  • Ask them to point at the hand(s) which you are opening/closing. (Inattention to one side = contralateral parietal lesion.)

Visual fields

  • Ask the patient to cover one eye with their palm and close your eye on the same side (without using your palm if you can)
  • Ask them to stay focussed on your open eye
  • Select a white visual fields pin and bring it in from the periphery, keeping it at mid-distance between you and the patient
  • Ask them to tell you when they can see it. Move in a diagonal direction into each of the four quadrants.
  • Test both eyes individually, comparing their fields with yours
  • Pathology:
    • Mononuclear field loss = intra-ocular pathology or ipsilateral optic nerve lesion
    • Bitemporal hemianopia = optic chiasm compression
    • Left/right homonymous hemianopia = contralateral optic tract/radiation lesion, or occipital cortex if macular sparing is present

Blind spots

Offer to test blind spots.

  • While the patient keeps both eyes open and focussed on you, hold a red pin mid-distance between you
  • Check they can see it as red in the middle (central scotoma = optic nerve lesion)
  • Now move the pin horizontally towards the periphery in each direction and to tell you when it disappears
  • Map each of their blind spots against your own (large blind spot = papilloedema)
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Visual field defects

Reflexes

Accommodation

  • Ask the patient to focus on a distant object, then hold your finger close to their face and ask them to focus on it
  • Pupils should constrict and eyes should converge

Direct and consensual papillary reflexes

  • In a dimmed room, ask the patient to hold an open hand between their eyes and focus on a distant point in the room
  • Shine the light at each pupil in turn from about 45°
  • Observe for direct and consensual papillary constriction
  • Defects:
    • Afferent defect (i.e. pupils are symmetrical but when light is shone in affected eye, neither pupil constricts) = CN2 (optic nerve) lesion
    • Efferent defect (affected pupil is persistently dilated, whilst other is reactive to light being shone in either eye) = CN3 lesion 

Swinging light test

  • Swing the light between the two eyes – the pupil size should stay the same regardless of which eye the light is shone in
  • If pupils become more dilated when the light is shone in one eye, then that eye is less sensitive to light and, hence, there is a relative afferent pupillary defect in that eye (partial optic nerve lesion on that side)

Ophthalmology

  • Ask the patient to remove glasses if present; consider preparing pupils with mydriatic drops (e.g. tropicamide); and use a darkened room
  • Ask the patient to focus on a point in the distance until you tell them otherwise
  • Red reflexes: look through ophthalmoscope at patient’s pupil from 1 metre away (lost in: cataract, retinoblastoma, vitreous haemorrhage)
  • Hold the patient’s right shoulder with your left hand and the ophthalmoscope in your right to examine the right eye (and vice versa for the left). First focus the ophthalmoscope to your vision by looking through it at a point in the distance and adjusting the focus wheel. Now look in the patient’s eye and adjust the wheel to focus the ophthalmoscope on their retina. When their retina is in focus, look at:
    • Optic disc: visualised by aiming the ophthalmoscope slightly nasally. Check the 3Cs:
      • Cup – normal cup to disc ratio is 0.3 or less, i.e. the cup occupies 3/10 of the diameter of the entire disc (enlarged = glaucoma)
      • Colour (grey/pale = optic atrophy)
      • Contours (swelling = papilloedema)
    • Four quadrants: follow the blood vessels out from the optic disc in each direction to visualise each of the four quadrants. Observe for:
      • Hypertensive retinopathy signs (silver wiring, AV nipping, cotton wool spots, papilloedema)
      • Diabetic retinopathy signs (dot and blot haemorrhages, cotton wool spots, neovascularisation, retinal fibrosis) 
      • Other characteristic appearances, e.g. drusen (macular degeneration), peripheral pigmentation (retinitis pigmentosa)
    • Macula: visualise by asking the patient to focus on the light of the ophthalmoscope. Should be pink (dark = macular degeneration).

Learn more here…

Learn about the findings of conditions you may see on fundoscopy and see examples here!

Extra-ocular muscles

Ask if the patient has any double vision and to tell you if they experience any during the test. 

  • H-test: ask patient to keep their head still (you may need to hold a finger on their forehead) and, with both eyes open, to follow your finger. Make an ‘H’ shape. 
    • Pause when they are looking laterally (nystagmus = cerebellar pathology)
    • If there is complex ophthalmoplegia, ask them to look straight up while counting down from 20 (fatigability suggests myasthenia gravis)

NB: CN3 supplies all extra-ocular muscles except Superior Oblique (CN4) and Lateral Rectus (CN6) – SO4LR6

Eye movement pathology

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Actions of the extraocular muscles

To complete

  • Thank patient 
  • Summarise and suggest further investigations you would consider after a full history

Some viva questions for you

What are the stages of diabetic retinopathy and characteristic findings of each stage?

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What are the grades of hypertensive retinopathy and characteristic findings of each grade?

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What are the definitions of these pupil abnormalities: miosis, mydriasis, anisocoria?

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What are the definitions of these refractive abnormalities: hyperopia, myopia, presbyopia, astigmatism?

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Try some OSCE stations

  1. Visual cranial nerves
  2. CN6 palsy
  3. Horner’s syndrome
  4. Find more here
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