Meta information labeled as Visual Impaired is typically found in video files. However, different kind of Visual Impaired information can also be found in image and document files. Usually, any kind of file that contains visual data like text, moving or still images can contain a help for people with a visual impairment or disability.
There is something most Visual Impaired features have in common: they make up for the lack in visual content shown to a visually impaired person by providing audio information that explains what is visually shown in a video or image or is represented as typed text.
For example, a video designed for visually impaired people to enjoy as well, most likely contains a certain audio track that explains the setup of a video, informs the listener when people move and interact, etc.
Image files can contain mostly textual information about the motif of the picture or photo which can be interpreted by software that reads out information to a visually impaired person.