Visuoperceptual Impairment

Visuoperceptual distortions are problems that involve both vision and perception. Common mistakes are illusions (seeing a face in a shadow), misperceptions (mistaking a stain on the carpet for a hole), and misidentifications (difficulties distinguishing daughter from grandaughter).

Understandably caregivers might mistake these distortions as delusions. But it is important to know that what the person with dementia is experiencing is not a true delusion. It is not based on incorrect reasoning or delusional thinking. Rather, it is the result of damage to neuro-visual system. Consequences include but are not limited to:

• needing more time to adapt to changes in light levels (eg when going from a dark room into sunlight or viceversa)
• changes in the reaction of the pupil to light
• loss of peripheral vision (being able to see things outside of the direct line of vision),
• reduced ability to differentiate colours
• problems directing or changing gaze
• problems with the recognition of objects, faces and colours
• loss of ability to name what has been seen
• double vision
• problems with depth perception.

As a result a person  may:

• become lost or disorientated, even in familiar places
• have problems locating people or objects
• misinterpret reflections (i.e. seeing an 'intruder' or refusing to go into a bathroom because it appears occupied, mistaking images on the TV for real people).

Regular eye examinations are important since cataracts, glaucoma, macular degeneration and retinal complications from diabetes also cause visuoperceptual distortions.

As a caregiver, the best approach is not to point out or correct distortions unless they are disturbing to the person experiencing them.