Dementia and Vision Problems

Dementia and vision problems (visoperceptual difficulties) may occur for many reasons:

Normal aging

Other medical conditions of the eye

Damage to different parts of the visual system from different types of dementia

Are common causes that must be considered when working with a person with dementia.

The person with dementia and vision problems can present differently by each individual. These “vision problems” may include

• A person seeing illusions
• Having misperceptions
• Misidentifications
• And even hallucinations.

The result of these “vision problems”  can be more severe for  a person suffering with dementia… than for an individual without dementia. This is because a person with dementia may not understand.. or remember, that they are having “vision problems”. or  have the ability  or be a able to rationalize  and  “test reality”.

Dementia and vision problems… have been reported for a number of types of dementias including:

Vascular dementia. With vascular dementia vision problems may occur if stroke-type damage occurs.. on or near the visual pathway in the brain.

Vision studies of Alzheimer’s dementia has had the  research of all the dementias. To help you to better understand what may be occurring with your family member with dementia… you must first understand … the complex nature of visual perceptual issues.

Simply put, when a person sees something they must interpret what they see. Then understand and process that information. Whether a person with dementia has good vision or not, they may try to understand what is seen. Then make a “guess” at what they are seeing.

What a person “sees” and then interprets they “see” can be very different from reality. However, it is their reality, and does affect a persons behavior.

What is accurate perception?

This is a term that refers to  a person seeing with the eyes… and  then ‘perceiving’ or interpreting the information with their eyes. As well as using their other senses.

A person without dementia, has the ability to co-ordinate all the parts of the eye system. This includes the eyes, optic muscles, retinas, and optic nerve. They then process the information from the other senses. There is also a cognitive process that must occur in this process. This requires the coordination of systems to make sense and process what was seen.

A person with dementia and vision problems… this “perception” will depend on the visual system and brain connections. The mental alertness of the person… as well as their mood,…even the of the person’s expectation of what they  ‘should’ be seeing play a part in the process.

There are many different components to the eye and sight process. The eye must adjust and maintain optimal focus.

The eyes adjust to:

• Various and changing light levels
• Perception of depth of field
• Determine white and black
• Identify colors
• Lines
• Objects
• Faces
• Identify and distinguish differences for facial recognition
• Separate objects from the background.

The eye must also make small and accurate eye movements. They follow moving objects and then send that information to the brain.

An aging person may experience many possible types and combinations of visual difficulties.

Normal Age-related Changes in Vision

Visual changes resulting from normal aging can include:.

• reduced visual acuity (sharpness– nearby objects become blurred first).
• an increase in the amount of light needed to see.
• an increase in the negative effects of glare.
• more time required to adapt to marked changes in light level (from dark to light or vice versa).
• a reduction in size of the peripheral visual field.
• decreased contrast sensitivity.
• decreased depth perception.
• changed color vision. Increased color saturation required to see colors. Gradual loss of the blue/violet part of the color spectrum. Dark colors and pastel shades become increasingly difficult to distinguish between.
• Changes in the small eye movements. These are used to track moving objects, orientate oneself in new locations, and to read.
• Blurring from ‘floaters’ (clumps of cellular debris in the vitreous humor gel in the eye).

Most people have regular sight tests. They adjust automatically to their changing vision as they get older. They can use glasses, problem-solve, or learn to compensate for visual changes. People with dementia, may not be able to do this.

Illnesses, Drugs, and Medications Can Affect Vision

Many visual disorders are commonly associated with aging.

These include cataracts, glaucoma, macular degeneration and retinal complications from diabetes. These can all result in changes such as

• Blurring
• Partial loss of visual field
• Genuine visual hallucinations
• And complete blindness.

Sometimes medications can contribute or cause to visual difficulties. Many medications taken by older people can have visual side effects.

More Visual Difficulties in Some Types of Dementia.

Dementia… related to Parkinson’s disease and Lewy body dementia… have shown to visual difficulties. In vascular dementia… if the stroke occurs along or near the visual pathway… a wide range of visioperceptual difficulties… including hallucinations, can result.

Changes in vision from strokes …may not be noticed by an individual.

Specific difficulties that have been reported in Alzheimer’s disease include:

• Reduction in number and accuracy of small eye movements.
• Color perception (loss of the blue, purple, green part of the spectrum).
• Figure-background contrast discrimination.
• Depth and motion perception.
• Visual acuity (but not initially).
• Object and facial recognition.

Some noticeable consequences of such problems include difficulties with:

• Assembling puzzles.
• Reading books, or doing visual tasks involving close eye movements.
• Watching TV shows with rapidly moving images.

Less obvious difficulties may involve the ability to:

• Play board games.
• Keep handwriting in horizontal lines.
• Find objects readily (even though they may be in front of a person).
• Copy images accurately.
• Walk confidently.

The consequences can be more severe for people with dementia… than for people without. Since they may not know (or remember) that they are making ‘visual mistakes’. Or be able or rational to ‘test reality’

Normal aging on the visual system, many cause visual disorders associated with aging.