25th December 2023

Differential diagnoses

The most important distinction in the assessment of TVL is vascular (amaurosis fugax) vs non-vascular aetiology.

Vascular causes

• Emboli
  • TVL can occur due to embolic occlusion of the retinal, optic disc, and choroidal blood vessels.
  • Often, the emboli may be visible on ophthalmoscopic examination.
• Ocular ischaemic syndrome
  • Ocular ischemic syndrome (OIS) is a disorder of ocular function that occurs subsequent to the stenosis of the carotid artery.
  • TVL occurs over seconds to minutes.
  • The eye may be red from dilated conjunctival and episcleral vessels.
  • There is usually a slow, progressive decline in visual acuity over weeks to months.
  • Characteristic features include episodes precipitated by bright light and dull ocular pain often relieved by lying down (‘ocular angina’).
• Migraine
  • May cause transient monocular visual loss due to retinal vasospasm.
  • Episodes may last minutes to hours, and there may be a history of stereotyped events.
  • An associated headache is common.
  • Mostly, the visual loss is transient, lasting 5 to 20 minutes, and may recur several times during the day.
  • Other visual disturbances include monocular positive visual phenomena (flashing lights or scintillating scotoma).
• Haematological abnormalities
  • Severe anaemia, sickle cell disease, and hypercoagulable states may cause episodes of transient visual loss.
• Vasculitis
  • vision loss in GCA may be heralded by TVL.
  • Examination reveals a swollen optic disc.
  • There may be concomitant systemic symptoms (See above section on GCA)