The type of sight impairment resulting from the stroke depend upon where, in the brain, the stroke occurs.
Visual field loss
This is common after a stroke and means that the person cannot see a full field of view. The degree of loss can be assessed by an opthamologist who can measure how much a person can see to the left or right of the centre of the field of vision. This is called a field test.
Once someone has become aware of this impairment to their sight, they can often learn to adjust to it so that it has less affect on their day-to-day lives.
Visual problems after a stroke often resolve themselves in time as the problem is not in the eye itself but is a result of damage to the brain at the time of the stroke.
Meaning ‘without half-vision', Hemianopia is a type of visual field loss where the person only sees either the right half or the left half of things out of each eye. For example, they may only see the left side of a piece of paper, or they will only see the right side of a TV screen
This can be very slight to a more severe visual loss. Difficulties in reading or missing food on one side of a plate can occur. However, just as with Visual field loss, once a person is aware of the problem, they can be taught strategies to compensate for these difficulties.
With visual neglect the eye and visual pathways to the brain are intact. However there can be an alteration in awareness and perception of the world due to physical damage to the brain. A person will be unaware of objects and people on the affected side and can bump into things or ignore people.
Other visual problems can also occur after a stroke including Quadrantanopia when a ¼ of the visual field is missing. There can also be abnormal eye movements, double vision or blurred vision.