The Market - Some Facts
  
There is a significant commercial demand and related opportunity for such a system:
There is an estimate that approximately 1.3 billion people in the world live with some form of
vision impairment. With regards to distance vision, 188.6 million people have mild vision
Impairment, 217 million have moderate to severe one, and 36 million are blind:
https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment
More than 3.4 million Americans in age of 40 and older are either legally blind or visually impaired:
https://www.nih.gov/news-events/news-releases/visual-impairment-blindness-cases-us-expected-double-2050
It has been estimated that there are 35,000 - 40,000 deaf-blind people in the US:
https://nationaldb.org/library/page/1934
In the UK, there are almost 2 million people living with the sight loss, and around 360,000
are registered as completely or partially blind:
https://www.nhs.uk/conditions/vision-loss
Visual impairment is assumed to be around 80,000 to 500,000 blind and 215,000 to 1 million
visually impaired persons in Germany. The table shows some data for Rhineland, one of the
largest areas in Germany:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3402073/