Twitter added a feature to enter description to the images and hence the company extended the service to visually impaired people, thereby those people can access the description via assistive devices such as screen readers and barille displays. These improvements increases its audience numbers and thereby a wider people can participate in conversation and can share experience together.
This feature is available in android and iOS twitter apps and it can enable using compose image descriptions options in accessibility settings of the twitter apps. Users can add a description in image of maximum 420 characters.