Visual Loss/Disturbance

NB Most visual disturbance diagnoses are based on examination but a good history is key too.

History

  • What kind of disturbance?
    • Central vs peripheral? (macular degeneration vs retinitis pigmentosa)
    • Fields? (neurological/optic pathways)
    • Blurriness? (Acuity problem/cataract)
    • Double vision? (cranial nerve palsy/strabismus)
    • Curtain-like? (occlusion/amaurosis fugax)
    • Haloes? (glaucoma)
    • Floaters/flashes? (detachment/vitreous haemorrhage)
  • Timing?
    • Superacute vs Acute vs Gradual vs Chronic
    • Progressive/single episode/episodic
  • Associated symptoms?
    • Pain?
    • Headache?
    • Vomiting/nausea? (closed-angle glaucoma)
    • Confusion?
  • Family History; Medical History; Drug History (antihistamines, anticholinergics, thiazides, indomethacin, ethambutol, antimalarials etc); social history

Examination

NB This is the full visual examination.  Most patients will only require certain sections of this where there is a relevant history and/or clinical suspicion.

Inspection

  • The eye, eyelids and lacrimal ducts should be looked at to check for any redness, proptosis, lid abnormalities etc etc
  • Lid lag should be looked for when appropriate by asking the patient to follow your finger down in the vertical line, checking if you can visualise sclera above the iris
  • Fluoroscein should be used to inspect the cornea where ulceration/abrasions etc are suspected.
  • The lids should be everted to inspect the conjunctiva in conjunctivitis

Visual Acuity (NB This is a test done in almost every patient)

  • With one eye at a time (with glasses on), test far sight with a Snellen chart at 6m.
    • If the patient cannot read to 6/6, a pinhole may be used to improve acuity (in an OSCE it is unlikely you will have to do this
    • If the patient cannot read the top line, bring the chart to 1m and ask again; If this is still difficult, ask to count fingers/hand movement/ light
  • IF the patient is complaining of central loss, check close reading with appropriate charts

Visual Fields (NB should only really be tested if there is suspicion of a field defect.  This could be suggestive of a central (CNS) cause of visual loss or a vascular cause)

  • To test for homonymous defects
    • With you sitting 1 metre away at the patient’s level, with both eyes open and the patient focusing on your eyes:
      • Hold both arms out and wiggle a finger of one hand.  Ask the patient to point to the one that moves.
      • Do this at 10/2 o’clock and 4/8 o’clock
    • For sensory inattention
      • Move both fingers at the same time and check the patient responds to both
  • For peripheral fields
    • Test each eye separately (i.e. ask the patient to cover one eye while you cover your opposite (corresponding) eye)
    • With your finger at the corner of each quadrant moving centrally, ask the patient to say when they see your finger entering their vision
      • NB if you finger is equidistant from you and the patient, this should occur at the same time as your finger enters your visual field.
    • Repeat for the opposite eye
  • For Central visual field and colour desaturation
    • Use a red hatpin to test each eye individually, again comparing to your own
    • With the hatpin as close to fixation as possible, ask what colour it is
      • e.g. pink/white (colour desaturation- e.g. optic neuritis)
    • Do a similar test as for peripheral fields but with the hatpin, asking at what stage does it go from black to red
  • For Blind spot (in practice rarely actually done)
    • In the same configuration as the previous tests, find your own blind spot (slightly inferotemporally) and compare that of the patient’s

Strabismus and Cover tests/Diplopia AND Eye movements

  • Inspect for a manifest squint/ obvious muscle weakness
  • From about 1m away, ask the patient to look at your pen-torch and observe the reflection off the cornea (should be central- a weak eye will have an off-centre reflection)
  • Ask the patient to follow your finger in a cross and an ‘H-shape’ and ask where diplopia is maximal, inspecting the eye movements for any problems.
    • On down gaze you may have to lift the lids up a bit
    • Look for nystagmus too and describe it if present e.g. direction and location, fast/slow/rotational etc
  • Cover tests
    • Cover one eye with the patient fixating on your pen torch
    • Observe the non-covered eye the first time.  Repeat and observe the covered eye as it is uncovered.
      • If either eye has to move to fixate, a manifest squint is present (eso/exotropia)
    • Repeat with the other eye
    • Next, cover one eye, then move to cover the other and then continue alternating, observing any eye movement as you do so
      • If there is eye movement, a latent squint is present (eso/exophoria)

Pupillary Examination

  • On shining a pen-torch into one of the eyes, look for both direct and consensual light reflexes
  • Check convergence/accommodation by bringing your finger from a distance towards the patient’s nose while asking them to look at your finger.  (Pupils should constrict)

Colour vision(rarely done in clinic)

  • Use ishihara slides.

Direct Ophthalmoscopy

Should be in a dimly lit room.  In general, use the same hand and eye as the patient’s eye you are examining.

  1. Check the red reflex
    1. Standing 1m away, with the lens at 0 and the scope at largest diameter/full brightness, shine the light onto each eye, looking for the red reflection of the retina.
      1. Comment on clarity, brightness etc
  2. Inspect the eye from front to back.  Ask the patient to look straight ahead on a fixed point.
    1. Dial the lens (clockwise) to the black 10 (+ve).
    2. Come towards the eye until the cornea (front of the eye) is in focus.  If done at roughly 45°, you should be able to see the optic disc most quickly.
    3. Inspect the cornea and conjunctiva briefly, commenting on any abnormalities seen e.g. FB, ulceration, abrasion, injection etc
    4. Dial down the lens and come closer to the eye until the retina is in focus
      1. In a ‘normal’ eye this is at lens 0.
      2. In a myopic eye, you may require to dial further into negative lenses (the reverse may be true for hypermetropic eyes)
      3. Similarly, you may have to adjust for any refractory error of your own eye.
    5. Examine the retina- 6-point examination
      1. Optic disc
        1. Cup
          1. the outer rim should normally be less than 50% of the diameter (a cup to disc ratio of 0.3 is normal and above 0.5 is pathological)
        2. Colour
          1. Normally orange/pink.  If pale, may be an optic neuritis? or other nervous pathology
        3. Contour
          1. Regular/irregular
      2. 4 vascular arcades- follow the vessels and describe any pathology e.g. hard/soft exudates; cotton wool spots; dot/blot haemorrhages; flame haemorrhages; drusen; laser scarring; detachment etc etc.  Start with superotemporal
      3. superonasal
      4. inferotemporal
      5. inferonasal
        1. NB it may be helpful for the patient to look in the opposite direction for you to have a better look at each corner of the eye.  Always ask in an exam.
      6. Macula
        1. traditionally viewed by asking the patient to look directly into the light, although, again, can often be viewed fairly well without this aid.
  3. Repeat on the other eye.

Potential Causes

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