Understanding the biology
Each of our eyes processes a right and left ‘visual field’; this refers to everything we can see at any given time. Your optic nerve sends the information from your left visual fields to the right side of your brain, and from your right visual fields to the left side of your brain.
As a result, the right side – or ‘hemisphere’ – of your brain is responsible for understanding the information sent from your left visual fields.
Our brains are structured into two hemispheres. Usually, an incident like a stroke will occur in one of these two hemispheres, leaving the other one unaffected.
When a person has a homonymous hemianopia, half of the visual field in both eyes is lost.
How might that affect your vision?
It depends on the exact location of any issue or event in your brain. Your level of vision will change depending on your circumstances. While there are specific names for different types of visual field loss – including homonymous hemianopia, quadrantanopia, and incongruent hemianopia – they all cause a functional change in vision.