Sadly Lydia Machell has had to stop her work on Prima Vista, in a twist of fate because of problems with her eyesight.
Dorico cannot feasibly be used by a blind user at the moment, I’m afraid, which is something I very much want to remediate in the future. Sibelius has been making some good developments in this area recently, and so has MuseScore. There is no way to say it other than that Dorico lags a long way behind in this area at the moment.