It is important to determine whether the vision loss occurred suddenly or gradually and establish the duration of symptoms. Ask if the problem is monocular or bilateral and also whether pain has featured.
A logical and calm approach is important to help make an appropriate working diagnosis and appropriately timed referral.
The most common cause for blind registration in the UK is senile macular degeneration.
Red flag symptoms
- Red eye
- Rapid onset
- Focal neurology
- Diabetic patient
- Amaurosis fugax
In the early stages vision becomes distorted; for instance straight lines appear bendy. Such patients should be referred urgently to the ophthalmology outpatient clinic.
Transient vision loss
Painless and sudden transient loss of vision in one eye is most common and generally reflects vascular pathology.
Termed amaurosis fugax, it is often described 'like a curtain descending'.
It should be treated as a warning sign of more permanent change. Ask about symptoms suggestive of temporal arteritis or TIA.
TIAs should be risk stratified using the ABCD score1, and aspirin commenced and appropriate referral made.
Vision loss with pain
In the case of pain and sudden visual deficit, acute glaucoma must be considered. This can affect one or both eyes. The eye usually appears red and feels hard to the touch. The pupillary response is lost. Any patient presenting with these features should be seen by the ophthalmology team the same day. Early intervention can be sight saving.
Optic neuritis causes a less severe eye pain, usually worse on movement, associated with reduced acuity. Optic neuritis is associated with multiple sclerosis.
Sudden complete blindness
Sudden complete blindness is thankfully rare. Causes include bilateral occipital strokes or trauma, rapidly progressive compression from space-occupying lesions, bilateral optic nerve damage or severe bilateral papilloedema, for instance from methanol ingestion.
In these circumstances eye pain is not usually a feature, although headaches, vomiting and neurological signs are likely.
Retinal detachment may develop slowly or suddenly. Often a history of head or eye trauma precedes onset of flashing lights prior to blanket vision loss.
Diabetes and hypertension are associated with chronic retinopathy. Tight glucose and BP control can help delay change and regular diabetic checks are vital to monitor disease progression.
Symptoms may improve but referral for laser ablation is recommended. Arterial emboli are of more abrupt onset.
- Dr Cumisky is a GP locum in Bath
1. Rothwell P M, Giles M F, Flossmann E et al. A simple score (ABCD) to identify individuals at high early risk of stroke after transient ischaemic attack. Lancet 2005; 366: 29-36.