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uk Health & medical scares new vision changes • flashing lights in vision • sudden blind spot • blurred vision sudden • new floaters and flashes • dark curtain in vision • shadow moving across vision • sudden loss of vision • one eye vision change • both eyes blurred vision • halos around lights • eye pain with blur • visual field loss • zigzag lights aura • migraine aura vision • transient vision blackout • vision changes after injury • vision changes after surgery • sudden dizziness with vision • headache with vision changes

What to do if…
you notice new vision changes like flashing lights, blind spots, or blurred vision

Short answer

Treat new or sudden vision changes as urgent. If you suddenly cannot see from one/both eyes, have severe eye pain, or think it could be a stroke, call 999 or go to A&E (do not drive yourself).

Do not do these things

  • Do not drive yourself to get help or “see if it clears” while you keep going about your day.
  • Do not rub or press on the eye, or keep “testing” your vision by straining.
  • Do not assume it’s “just migraine” if this is new for you, one-sided, or comes with a dark curtain/shadow or a sudden increase in flashes/floaters.
  • Do not use someone else’s prescription eye drops (especially steroid drops) “to see if it helps”.
  • Do not ignore vision change with face drooping, arm weakness, or speech trouble.

What to do now

  1. Go to A&E or call 999 now (and do not drive) if any apply:
    • You suddenly cannot see from 1 or both eyes (even if it comes and goes).
    • You suddenly have severe eye pain.
    • You have vision change plus possible stroke symptoms (face weakness/drooping, arm weakness/numbness, speech problems, confusion, severe sudden headache, collapse).
  2. If you do not have the emergency signs above, but you have new flashes/floaters, a new blind spot, or new blurred vision:
    • Ask for an urgent optician appointment or get help from NHS 111, especially if any apply:
      • it’s the first time you’ve had floaters or flashes
      • they started suddenly or the number suddenly increases
      • you notice a dark “curtain” or shadow moving across your vision
      • you also have blurred vision or eye pain
      • it started after eye surgery or an eye injury
  3. Make a quick “one-minute note” to take with you (or read to the call handler):
    • Exact time it started, which eye (left/right/both), and whether it’s constant or comes/goes.
    • What you noticed: flashes, new floaters, blur, blind spot, curtain/shadow, double vision, pain, headache, nausea.
    • Any recent injury, eye surgery, or new medication changes.
  4. Do one simple, safe check (no straining):
    • Cover one eye at a time and look at a fixed object to see if it’s in one eye or both.
    • If symptoms are severe or rapidly worsening, stop checking and focus on getting urgent help.
  5. Reduce risk while you’re getting help:
    • Stop driving/cycling and avoid ladders/machinery.
    • If you wear contact lenses and have redness/pain, remove them if it’s easy and comfortable—then keep them out.
  6. Prepare for assessment:
    • Bring a list of medicines (and any eye drops) and your glasses/contact lens details.
    • You may be given pupil-dilating drops (temporary blur/light sensitivity), so arrange someone to accompany you or get you home.

What can wait

  • You do not need to decide what the cause is right now.
  • You do not need to search symptoms online or compare stories.
  • You do not need to “prove” it’s serious before seeking urgent help.
  • You can leave follow-up planning (work cover, childcare, longer-term treatment decisions) until after you’ve been assessed.

Important reassurance

It’s common to feel alarmed by sudden vision changes. Many causes are treatable, and getting assessed quickly is the safest way to protect your sight and rule out emergencies.

Scope note

This guide covers first steps only: choosing the right level of urgent care, avoiding common mistakes, and recording key details. Further tests and treatment depend on what clinicians find.

Important note

This is general information, not a diagnosis. If you think you may be having an emergency, seek urgent medical help immediately.

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