Retinitis pigmentosa causes night-blindness and a loss of peripheral vision (side vision) through the progressive degeneration of the retina. The retina is a light-sensitive tissue at the back of the eye and is crucial for vision.

Routine ophthalmic check ups are important to monitor any changes in a person’s vision and detection of further complications (e.g. cataracts).

As retinitis pigmentosa progresses, the field of vision narrows, a condition known as ‘tunnel vision’, until only central vision (the ability to see straight ahead) remains. Many people with Usher syndrome also have balance problems.

The cells on the retina, called rod cells, gradually stop sending information about changes in light levels and the shape of objects.

How vision is affected

At an early stage the central vision is unaffected, but a person may first notice visual problems at dusk or in poor light, so-called night blindness, and also a gradual reduction in the field of vision, loss of the outer edges of vision, resulting in a tendency to miss things or trip over things. Later, reading vision (detailed vision) and colour vision are affected.

Some people experience changes to the cone cells in the centre of the retina, although this is quite rare. This is the area that is responsible for detail and reading vision. A person with loss of central vision may have useful side vision that, for instance, helps them to find their way around.

Varied deterioration

The pattern of vision loss is highly individual. The age at which symptoms start is variable and may vary with the three different types of Usher syndrome. The rate at which vision deteriorates is also variable but is generally very slow with changes occurring over years rather than months.

Many people retain their central tunnel of useful vision until quite late in life, thereby being able to recognise faces and continue reading. 

People with Usher are often sensitive to bright light and have difficulty adapting from one lighting level to another. They might also have difficulty judging depth or seeing some colours. People will adapt to these challenges, particularly in familiar situations.

Does Usher syndrome lead to blindness?

Few people with Usher lose their sight completely – that is, have no light awareness. The extent to which vision changes, and the rate that it changes, will vary. It is now known that these variations are linked to the specific gene that is responsible for a particular person’s Usher.

Many people with Usher become night blind in their teens or even earlier, but will keep normal vision in daylight and will be able to read and see fine detail. Loss of visual field also occurs over time. This influences the person’s ability to see around them and move around safely, particularly in unfamiliar areas.