Blurry vision


A 21yo female presents to your emergency department with visual changes.

You are to take a history, outline your differential diagnosis and discuss what Ix the patient might need. You are NOT to examine the patient.

Domains to be examined

  • medical expertise
  • communication

Instructions for the actor:


  • for the past 6 days you have noticed ‘blurring’ of your vision
    • your vision has steadily been getting worse and now you do not feel safe to drive
    • on further questioning, you mean that you have been noticing double vision
    • this is present all the time and is worse when looking left/right/down
  • during this time you have also noted heaviness of your eyelids which is always present but worse through the day
    • find that you have to consciously need to ‘pull your eyelids open with my forehead’
  • if specifically asked about limb weakness
    • for the past 4 days you have been finding it very tiring to walk around at the end of the day
    • also noticed poor performance in cardio at the gym due to rapid fatigue of limbs
  • you were recently treated for a kidney infection in the same ED 10 days ago
    • presented with classic features of pyelonephritis (fever, right flank pain, dysuria)
    • give IV antibiotics overnight and DC’d home from the ED on oral Abx
    • all of these symptoms have resolved
  • relevant negatives
    • no pain on eye movement
    • no weakness in the limbs (just returned from a hiking trip in NZ 2 weeks ago)
    • no headaches
    • no speech changes
    • no difficulty swallowing/chewing
    • have noticed some weight loss recently, ~5kg over the past 3 months without any dieting/exercise
    • occasionally waking up in the night with sweats


  • asthma
  • family Hx of lymphoma
    • mother and brother have both had this in their early 20s
    • you are very worried that these symptoms mean you have lymphoma
  • meds: OCP
  • social
    • non-smoker
    • social etoh
    • no illicit drugs
    • studying media at university

Questions to ask the candidate:

  • what do you think I have? (if they have not reached a differential)
  • is that definitely what I’ve got?
  • what tests do i need to have?


  • this patient presents with a classic history of myasthenia gravis
  • exacerbator may be gentamicin which had recently used to treat the patient’s pyelonephritis (for highly performing candidates)
  • DDx is certainly difficult:
    • note the constitutional symptoms and strong family Hx of lymphoma
    • gives the DDx of Eaton-Lambert (this is for highly performing candidates), GBS variant
  • Important parts
    • identifying primary DDx
    • identifying that the symptoms are rapidly progressive, thus the patient needs inpt admission and neurology review
    • that some tests can be sent from the ED (need only broad headings)
      • bloods: Anti-ACh-R Abs, anti-Musk Abs
      • spirometry: given this patient has limb involvement, it is important to identify any potential respiratory muscle weakness
      • CXR or CT chest (less urgent): looking for a thymoma
      • nerve conduction studies/EMGs


blurry-vision-osce (printable version)

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