Sudden changes in your vision should always be taken seriously. While some causes are benign, sudden visual symptoms can indicate sight-threatening or life-threatening conditions that require immediate attention. Knowing what to look for and where to go for help could save your sight.
Symptoms that require urgent same-day assessment include: a sudden increase in floaters (especially with flashes of light), a shadow or curtain spreading across your vision (possible retinal detachment), sudden loss of vision in one or both eyes (possible retinal artery or vein occlusion, or other serious conditions), sudden severe eye pain with blurred vision and headache (possible acute glaucoma), sudden double vision, and distortion of straight lines or a central blind spot (possible wet macular degeneration).
Symptoms that require emergency assessment (A&E or 999) include: sudden complete vision loss, a chemical burn to the eye, a penetrating eye injury, sudden vision loss accompanied by weakness, numbness, or difficulty speaking (possible stroke), and sudden severe headache with vision loss or changes (possible stroke or other neurological emergency).
For urgent but non-emergency symptoms, your first call should be to your local optician. Many opticians provide same-day emergency eye care through the NHS MECS scheme and have the specialist equipment needed to examine your eyes thoroughly. This is usually faster and more appropriate than A&E for eye-specific problems. If your optician cannot see you, call NHS 111 for advice on where to go.
Time matters with many of these conditions. Retinal detachment is best treated within 24 hours. Acute glaucoma can cause permanent damage within hours. Retinal artery occlusion (an eye stroke) has a very narrow treatment window. Do not wait and see if symptoms improve — seek help immediately. It is always better to be assessed and reassured than to delay and risk permanent damage.