According to its authors,
Optician Sans is a free typeface based on the historical eye charts and optotypes used by opticians world wide.
It features the same visual principles as the LogMAR chart (adjusted to be included in a functional display typeface), as well as a set of stylistic alternates accessible from your software’s Glyph panel.
The typeface, made with Sloan optotypes as the basis of construction, is the most effective letter selection for equal legibility. To make a typeface that ensures that all patients regardless of visual function, have the best possibility to see my commercial information, was a key goal for my new visual layout. This again shows the quality and passion I have for my profession, my practices and my patients.
Øyvind Krogh — Optometrist at Optiker-K.
Update 17 December 2018:
As of today Optician Sans was also added on Github, you can also check out the repository there.