Sensorium
Seen Differently

All patterns

Night blindness

You step out of the shop. Everyone else can see the street. You can't, for twenty minutes.

Typical visionWith night blindness
21 min to adjust: the street stays dark long after typical eyes have adjusted, and only the lights show.

Light
Minutes in the dark: 0The clock runs 60 times faster: one second is one minute.

Try it

You've just stepped out of the pharmacy. How many people are waiting under the street sign?

What's happening

Night blindness (nyctalopia) means your eyes adjust to the dark far more slowly than they should, or never fully. In the dark, vision depends on the rod cells of the retina, which need time to become sensitive after bright light. Healthy eyes take about 20 to 30 minutes to reach full night vision. When rods are damaged or short of vitamin A, that takes much longer, so dim streets, stairs and cinemas stay dark.

This simulation is for understanding and empathy. It is not a diagnosis and doesn't replace an eye examination.

What you might notice

Lights, but no people

You can see lamps and windows, but not the person standing under them.

Slow to adjust

Stepping from a bright shop into the street leaves you blind for minutes.

Dusk is the hardest time

As the light fades, the world goes grey and flat before anyone else notices.

Fine in daylight

In good light your vision can be completely normal.

Where it gets hard

  • Driving at dusk and at night.
  • Stairs, kerbs and steps outside after dark.
  • Cinemas, theatres and restaurants with dim lighting.
  • Finding your way at night, at home or in someone else's.

Often caused by

Conditions commonly linked to this pattern.

  • Retinitis pigmentosa, often the first sign
  • Vitamin A deficiency, a leading preventable cause in children worldwide
  • Cataract
  • Advanced glaucoma
  • Congenital stationary night blindness
  • Some medicines, and surgery or disease that affects vitamin A absorption

Treatment and support

Treatment follows the cause. Vitamin A deficiency is treated with supplements, and night vision often returns within weeks. Cataract surgery usually helps a great deal. For retinitis pigmentosa there is one gene therapy for a specific mutation (RPE65), with trials running for others. Good lighting at home, a torch, and avoiding driving after dark help in the meantime.

Looking for research you could join? Search ClinicalTrials.gov or the EU Clinical Trials register.

How to help someone with sight loss

  • Say who you are when you approach, and tell them when you leave.
  • Offer your arm rather than pushing or pulling, and mention steps and kerbs.
  • Use large, high-contrast print and good light, and read labels and doses aloud if asked.
  • Don't move their things without saying: a moved cup or key is a lost one.

Get checked the same day if

Night vision suddenly gets much worse, or comes with a loss of side vision, flashes or a curtain over your view.

If it's sudden or comes with other symptoms, go to an emergency department.

Where to learn more