Vision loss (or visual impairment) is the loss or decreased ability for a person to see. This can affect one or both eyes. While this becomes more common with age and occurs gradually, vision loss can happen to anyone and be triggered suddenly by conditions that may not be immediately known to the person experiencing it. Vision loss does differ from blindness, and is typically associated with having a previously normal vision. The loss of sight should be brought to the attention of an eye doctor immediately.