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Visual disturbance

"Eye patch" is a common cause of unilateral visual loss. Check your patient is not wearing an "eye patch" before examining. If you manage to remove it, you may cure the condition.

Definition

Epidemiology

Common.jpgHappens a lot. Go figure.

Differential Diagnosis

Visual loss is generally split up, at least with regards to a differential, in terms of time.

Acute (possibly)

These are the really important ones. If you don't identify them, then somebody might go blind - or die.

Not acute (probably)

Clinical and Associated Features

Acute

  • Retinal vein occlusion - painless unilateral visual loss like a "light dimming" or "shade coming down". Often noticed on waking. On fundoscopy: engorged veins; haemorrhage with 'cotton wool' exudates (infarcts); retinal oedema; swollen optic disc; new vessel proliferation; papilloedema; vitreous haemorrhage.
  • Retinal artery occlusion - sudden visual loss in any possible field of vision. Uncommon but dangerous. Sudden, painless visual loss; poor direct light reflex, consensual is normal; pale and opaque retina; arteries pale, appear as red "threads"; fovea becomes "cherry red spot"; optic atrophy after a few weeks - optic disc goes white.
  • Giant cell arteritis - headache, scalp tenderness, blurred/lost vision, fever
  • Optic neuritis - inflammation of the optic nerve. Symptoms: variable central visual loss for 2-6 weeks; aching in region of the eye, aggravated by movement; central scotoma; loss of colour vision; relative afferent pupillary defect (RAPD); reduced visually-evoked response (a clever test)
  • Closed-angle glaucoma - visual disturbance (leading to visual loss), eye pain (can be in the eye, around the orbit or just a generalised frontal headahce), nausea & vomiting. Often it's due to the pupil getting caught on the lens which blocks aqueous outflow. As such, it often happens when the pupil is mid-dilation e.g. during stress or excitement, watching TV in dim lighting, in patients on mydriatics.
  • Wernicke's encephalopathy - if there's confusion and ataxia and the dude has a history of alcohol problems, think this.

Not acute

  • Diabetic retinopathy - gradual visual deterioration; on fundscopy: microaneuryms, exudates, 'cotton wool' spots, haemorrhages, neovascularisation
  • Age-related macular degeneration - gradual visual deterioration - usually starts with a central scotoma which gets bigger, causes difficulty with reading
  • Cataracts - lens opacities. Gradual visual loss; difficulty reading, recognising faces, watching TV; diplopia (double vision)
  • Papillloedema - bulging optic disc caused by raised ICP
  • Squints - double vision, moving head to compensate
  • Amblyopia/"lazy eye" - visual disturbance with no physical signs ("both the doctor and the patient see nothing")
  • Optic tract disorders - this will usually be vascular or a tumour. Look for the visual defect
  • Central nerve palsy - anything causing a palsy in nerves II, III, IV, V, VI could cause visual problems

Investigations

Generally, there are clever eye tests like visually-evoked responses and badass opthalmoscopy using clever machines but nothing particular.