Dementia and Visual Perception

How does dementia affect vision?

Dementia can have a major effect on a person's ability to process information visually.

Photo: Elina Araja, pexels.com

Examples include:

• Misperceptions: Seeing one thing as something else

• Misidentifications: Mistaking people or objects, such as a sibling for a spouse

• Reduced contrast sensitivity: Having difficulty distinguishing between objects and the background

• Reduced color vision: Having difficulty seeing different colors, especially similar shades

• Reduced ability to detect movement: Having trouble keeping up with fast-moving pictures / events

• Reduced depth perception: Having difficulty judging distances, understanding changes in elevation, and differentiating between flat and three-dimensional objects

• Changes to visual field: Having narrower peripheral vision when looking straight ahead, making it difficult to see things to the side

• Problems shifting gaze: Having difficulty changing gaze or looking in the right direction

It is critical to realize that these perceptual changes occur in the brain and have nothing to do with the eyes themselves. This is because medical issues such as strokes, Alzheimer's disease plaques, and Lewy Bodies can damage the occipital, temporal, and/or parietal lobes, where visual information is processed. It is important to maintain regular appointments with optometrists and ophthalmologists to monitor for cataracts, glaucoma, macular degeneration, and so forth to receive prompt treatment.

My loved one seems to be struggling with vision. What can I do to help?

Caregivers can modify the environment to help a person affected by dementia have less difficulty with visual perception. For instance, at mealtimes, having a high contrast between the plate and the food on it may make it easier for the person to see - such as mashed potatoes on a dark-colored plate on a contrasting placemat. Also at mealtimes, ensuring that the person is sitting at a distance where the plate can be seen - this may be closer or further from the table than where one naturally sits. Falls can also happen from the reduced contrast between the floor, steps, and objects that may be at ground level. One should also take care to speak directly and at eye level, and provide auditory and tactile cues rather than visual cues to help with recognition, identification, and perception - such as saying one's name or describing what is in front of the person ("your seat is two steps forward").

Can you suggest further reading about how dementia affects visual perception?

Read the Alzheimer's Foundation's article: https://alzfdn.org/dont-overlook-alzheimers-affect-on-eyesight

Originally published September 2024 in the NYMC newsletter.