Peripheral awareness
There is a whole world beyond the point you look at.
These demonstrations illustrate ideas about vision. They do not reproduce another person's experience, measure your eyesight or diagnose an eye condition. Real vision varies with the person, the lighting, the task and the surroundings.
Peripheral awareness
The visual field is the whole area you can see. Glaucoma damages the optic nerve and often affects side vision gradually, with no early symptoms.
Eye examinations assess more than reading letters. Rehabilitation services help with moving around, confidence and practical ways of using the sight you have.
Glaucoma does not always look like a dark tunnel. This fixed mask illustrates lost scene information, not a visual-field test or a stage of glaucoma.
Turn on JavaScript for the comparison controls and the scene selector.
Read the original sourceWhen the light changes, sight needs time
A change in the light can bring several difficulties at once. Cones handle detail and colour in brighter light. Rods handle dim light. Cone-rod dystrophy often affects cones first, with rod difficulties developing later, and the balance differs from person to person. Slow adjustment and a lasting problem in dim light are two separate things. Extra time helps with one but does not remove the other.
Think of walking into a hallway from a sunny street, or leaving a dim cafe. The difficulty changes while you stand in the same spot. Tell your eye-care team about both directions: what is hard straight away, what gets easier with time, and what stays hard.
This is a designed teaching sequence, not a measured adaptation curve. A 15 or 60 second playback is a demonstration length, not a prediction of how long anyone takes to adjust. A washed-out screen cannot reproduce light sensitivity or pain. Nothing flashes, and the rest of the page stays unchanged.
Sources checked 5 October 2026: RNIB: inherited retinal conditions, MedlinePlus: cone-rod dystrophy, Macular Society: cone dystrophy.
Beyond the picture
A change in sight can affect reading, getting around, work and recognising people. Choose a condition above for everyday examples and ideas to raise with your eye-care team.