Many people with Alzheimer's disease complain of poor eyesight, or problems hearing. These occur in different ways, at different stages .
The complaint of 'poor eyesight' often occurs in moderate to severe dementia, and often comes from families more than from patients. Families are reacting to the apparent inability of the person to see what is in front of them. While poor eyesight can occur, the problem at that stage is more often one of the failure of the person to process the information which would allow them to recognize what is in front of them. This is the problem of 'visual agnosia ', which usually becomes evident in moderate to severe dementia.
By contrast, many people with Alzheimer's disease complain of hearing difficulties in the mild stage of the disease. This can be poor hearing, but often also reflects a problem with attention and concentration. In a distracting environment, attentional capacity becomes overwhelmed.