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.


Next Step  Find out why dementia changes eyesight from expert Teepa Snow (2 min 49 sec)


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By DailyCaring Editorial Team


This article wasn’t sponsored and doesn’t contain affiliate links. For more information, see How We Make Money.


  • Reply February 1, 2021

    Sajeda Du Plessis

    I take care of my mum .She is getting worse by the day she is very abusive and her anger is bad. I try telling my family about her behaviour but they say I must accept it . is there any way of controlling her anger

  • Reply July 17, 2019


    My mother has dementia. We’re guessing stage 4.
    Her eyes have become beady and glossy. If she’s looking at you when a light is behind you. It’s reflective, like the eyes of an animal in headlights. It never used to be that way. Is this a normal side effect of dementia?

    • Reply August 3, 2019


      If you’re concerned that this could indicate a medical condition or medication side effect, it would be good to contact your mother’s primary doctor or her eye doctor.

      Every person is unique and may experience different physical changes as their dementia progresses. If these issues are causing problems or pain, then it’s important to let a doctor know they’re happening and get appropriate treatment. If they’re not causing harm or distress and aren’t caused by a medical problem or medication side effect, it may be better to let them be.

      • Reply January 16, 2021

        Susanne Moses

        I noticed the same thing in my aunt after her craniotomy. I wonder too if this is a sign of dementia. Or could it mean cataracts?

        • Reply January 17, 2021


          The best thing to do would be to share this concern with your aunt’s doctor and eye doctor so they can examine her to find the cause.

    • Reply August 18, 2021


      That is exactly what I saw today when I visited my sister, Does this mean that her life is nearing the end?

      • Reply August 18, 2021


        The only person who can diagnose issues with your sister’s health is her doctor. Something like a change in eyesight or behavior alone can’t be used to draw any meaningful conclusions.

  • Reply November 30, 2018

    Dr swapna Mukherjee.

    My husband is a dementia patient with all usual symptoms and also a very bad temper towards some selected persons.As acaregiver I hardly get sleepp for more than 2 hours.He protests against keeping a helping hand.Help.

    • Reply December 2, 2018


      I’m so sorry this is happening. Unfortunately, this is common in dementia. Because he doesn’t have the judgement to be able to accept that he needs help, the hiring of caregivers may need to be done against his wishes. If you’re able to hire caregivers who have experience in dementia care, they are more likely to get him to cooperate and accept their help. It sounds like you definitely need and deserve the help.

      We also have a number of articles that may be helpful:
      — 7 Ways to Respond to Mean Dementia Behavior
      — Our section on Alzheimers & Dementia Challenging Behaviors

      • Reply January 25, 2022

        Kareen Munro

        My father cannot find/see things that are right in front of him, no recognition that it’s there!?

        • Reply January 25, 2022


          It’s possible that this could be caused by a physical change in eyesight or by a change in the way his brain is processing what his eyes see.

  • Reply October 8, 2018


    Can Dementia affect hearing?

    • Reply October 8, 2018


      That’s a great question. There isn’t a lot of research in this area, but it makes sense that damage in the brain would affect how a person understands or processes what they hear. For example, someone with dementia could easily misunderstand something that you say to them. Or, they could have a hallucination or delusion based on a noise they heard. One thing that many experts and caregivers have found is that noisy environments can cause a lot of stress and agitation in some people with dementia — they become more sensitive to noise.

  • Reply May 3, 2018


    What causes dementia and why do we hear of so many more cases now than we used to do years ago?

    • Reply May 3, 2018


      Dementia is a broad collection of symptoms that can be caused by different health conditions. Doctors and researchers aren’t sure what causes diseases like Alzheimer’s, Lewy Body, or Frontotemporal dementia, and others, but causes for conditions like vascular dementia are better understood (

      It’s possible that we’re only hearing of more cases of dementia now because the population is living longer than ever due to advances in healthcare. In previous generations, many people would have already died from another health condition before any dementia symptoms became noticeable. It’s also likely that because awareness of dementia was very low in the medical community (and is still not widespread), doctors would misdiagnose dementia or attribute dementia-like symptoms to “senility” and not investigate further.

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