Signs
 

Reduced Visual Acuity

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Overview

  • Testing visual acuity is useful as a screening test for identifying reduced vision which may be due to ocular or neurologic disorders.
    • How to Elicit

    • Ask the patient to cover one eye, look at a Snellen chart (wall-mounted at 6m or handheld at arm's length) and identify the smallest line that they can read.
  • If the patient wears corrective lenses, perform the test with and without them.
  • If the patient's visual acuity is poor, use a pin hole over their eye to test for refractive error.
    • Causes of Poor Visual Acuity

    • Refractory error
    • Corneal opacification - cataract, infection, trauma
    • Vitreal opacification - intraocular haemorrhage
    • Retinal disorders - macular degeneration, retinal detachment, diabetic retinopathy, retinal artery occlusion
    • Optic nerve disorders - glaucoma (raised intraocular pressure), ischaemia, optic neuritis
    • Intracranial disorders - pituitary disorders, aneurysm
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