Dementia and Eyesight: 3 Common Changes and Behaviors

Vision changes can cause strange dementia behavior

Dementia causes a variety of changes in the brain, including how the eyes see and how the brain processes the information the eyes bring in.

When seniors with Alzheimer’s disease or dementia behave in strange ways, we might assume they’re hallucinating.

Hallucination is a possible symptom, but the behavior could also be explained by changes in their vision.

But this strange behavior can be incredibly stressful for us to observe. We think the worst of our older adult’s mental state and worry that they’re declining more quickly.

Knowing about vision changes helps you understand why your older adult could be doing these things, reduces fear and worry, and makes dementia care a little easier.

In this 2 minute video, expert dementia educator Teepa Snow explains how dementia can change vision and what type of behaviors we might see because of those vision changes.

Dementia and eyesight: 3 common changes and behaviors

1. Field of vision narrows
Teepa explains that by the time we’re 75 years old, the normal changes related to aging reduce our normal peripheral vision a little bit, so we’re not able to see and notice as much as we would when we were younger (17 sec in video).

When someone has dementia, their field of vision narrows to about 12 inches around. As Teepa says, it’s like wearing binoculars (33 sec in video).

If you were to use binoculars and try to move around normally, it would be very difficult.

2. The brain shuts down information, making it harder to see things right in front of them
As dementia advances, the brain may find that the information coming in through two eyes is too overwhelming.

So, it effectively shuts down the information coming from one eye – at that point, your older adult could basically be seeing through one eye (56 sec in video).

That means they lose depth perception and can’t tell if something is two-dimensional or three-dimensional.

That makes it hard for your older adult to know if something is a pattern in the carpet or an object on the floor, a real apple or a picture of an apple, or what the chair seat’s height is (1 min 23 sec in video).

 3. Changes in vision cause behavior changes that don’t make sense to us
These changes in vision can cause someone to do things that seem strange to us.

Teepa shows how someone might seem like they’re picking at the air, but they’re actually trying to turn off the ceiling light because it seems much closer than it really is (1 min 59 sec in video).

Because they don’t have depth perception, they don’t know how far away the light really is.

Your older adult might also bend over slightly and start picking at the air around waist level.

That looks strange to us, but they could be trying to pick something up from the floor. They just don’t have depth perception to know that the floor is still a couple of feet away.

This type of behavior might look very strange to us, but your older adult is just responding to the world as they see it and it makes complete sense to them.

If we were seeing what they were, we’d probably be doing the same things.

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Dementia and Eyesight: 3 Common Changes and Behaviors