Older people often have vision problems. Also, many drugs can disturb the eyes' ability to focus well.
Poor vision can increase the risk of falls and injury.
It can also make communication harder. Vision plays a big role in communication. We watch the facial expressions of other people as they speak and as they listen to what we have to say. Eye contact seems to mean a lot. Also, we often use gestures, like pointing or a shrug of the shoulders, instead of words.