Stroke

A stroke is said to occur when the brain does not function properly because it does not receive enough blood supply. Death of brain cells occurs.

Different parts of the brain control different body functions. If the particular part of the brain that controls a certain function does not receive it’s blood supply, that body function will be affected.

Risk factors for stroke include older age, hypertension, diabetes, smoking, high cholesterol and disturbances of heart rhythm. Strokes can be of 2 main types, ischaemic (most common type) or haemorrhagic strokes (less common).

Vision

Stroke: Left hemianopia in the right eye.

Stroke: Left hemianopia in the right eye. Image credit: AAO

When the posterior circulation of the brain is affected by a stroke and the occipital lobe is involved, vision will be affected. It is possible that only the vision is affected without other features.

When the occipital lobe is involved, vision  in each eye is affected in a pattern called a “hemianopia”.  In the case of a left hemianopia (see image to right representing right eye vision), the vision to the left of the vertical midline is affected.  Strokes cause a homonymous hemianopia meaning that both eyes are affected. The vision loss may not be apparent to the affected person. They may notice that they bump into objects or may be found by chance during a check by a healthcare professional.

These stroke related vision problems have effects on reading, driving ability and many other aspects of daily living.

Vision recovery after stroke

One-fifth of patients may make a full recover in the first month. Fifty percent will have some improvement over the first month. Most of the recovery occurs within the first 2 months post stroke but further recovery is unlikely after 6 months.

 

References:

Goodwin D. Homonymous hemianopia: challenges and solutions. Clinical Ophthalmology 2014.