Symptom

Halos around lights

Sudden painful halos are an emergency

Medically reviewed by · Last reviewed 2026-07-06 · How review works

When to get urgent help

  • Sudden halos with a painful, red eye
  • Halos with a headache, nausea or vomiting
  • Halos with sudden blurring or loss of vision
  • Halos soon after eye surgery with pain or redness

Common causes

Halos come from light scattering as it passes through the eye. These are common reasons.

Cataracts A cloudy lens scatters light, causing halos and glare at night. Glaucoma Acute glaucoma causes sudden halos with a painful red eye and nausea. Astigmatism An uneven focus can cause glare and starbursts around lights. Keratoconus A distorted cornea causes glare, halos and ghosting.

What can help

  • Book an eye test, as cataracts and focusing problems are common causes
  • Treat sudden painful halos with nausea as an emergency
  • Take care driving at night if glare affects your vision

Frequently asked questions

What causes halos around lights at night?

The most common cause is cataracts, along with refractive problems such as astigmatism. Sudden halos with eye pain and nausea can signal acute glaucoma and need emergency care.

Are halos around lights serious?

Usually not, when they come on gradually with cataracts. But sudden halos with a painful red eye, headache or nausea are an emergency and need immediate care.

Can glasses or surgery help halos?

Yes. Updating your glasses can reduce halos from focusing problems, and cataract surgery often removes halos caused by a cloudy lens.

Trusted sources

This page reflects established clinical guidance. For further reading, consult these authoritative eye-health organisations: