Sensorium
Seen Differently

All patterns

Half-field loss

Half of everything is gone, and your brain doesn't tell you it's missing.

Typical visionWith half-field loss
45% of one side gone: the left side of the view is gone in both eyes, cut off by a straight line through the point you look at. Move your pointer or finger to look around.

Try it

When is the eye appointment, and how many tablets go in each dose?

What's happening

After a stroke or another injury to the brain's visual pathways, the same side of the world can disappear from both eyes. This is called homonymous hemianopia. The eyes themselves are healthy; the part of the brain that builds that side of the picture is not. It can be a quarter of the view or a full half, and the edge runs straight down the middle of your vision.

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

What you might notice

A straight edge

The missing side stops at a sharp vertical line through the point you look at.

It follows your eyes

Wherever you look, the same side is gone, in both eyes.

Reading breaks down

Words at the start or end of each line vanish, so sentences stop making sense.

You don't feel the gap

The brain papers over it, so people bump into things on that side without knowing why.

Where it gets hard

  • Reading, especially finding the start of the next line.
  • Walking through crowds and doorways, and past furniture on the missing side.
  • Driving, which is usually not permitted with this kind of field loss.
  • Eating, when food on one side of the plate goes unnoticed.

Often caused by

Conditions commonly linked to this pattern.

  • Stroke affecting the back of the brain or the visual pathways
  • Brain injury after an accident
  • Brain tumours
  • Brain surgery
  • Less often, infection or inflammation

Treatment and support

Some vision can return in the first weeks and months after a stroke. After that the lost field rarely comes back, but people learn to work around it: scanning training teaches the eyes to sweep into the missing side, and prism glasses can shift part of that side into view. An orthoptist or low-vision service can assess what helps.

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

Part of your view disappears suddenly in both eyes, or it comes with weakness, numbness, a drooping face, slurred speech or a severe headache. Treat it as a stroke and call your emergency number.

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

Where to learn more