Unfortunately, the eyes, like much of the rest of the body, become more susceptible to disease and other issues as we get older. Some problems are serious and can lead to blindness, if left untreated. But for people with hearing loss, even a small decrease in vision can affect the ability to lip-read and thus understand better what they hear.
The combination of vision and hearing problems can also decrease the ability to socialize, which has been linked to a greater risk of dementia.