Atkinson Hyperlegible was modified from Helvetica style san-serif fonts, but with a few tweaks to make similar letters appear different. For instance, the capital I has serifs to help readers distinguish it from a lowercase L, a numeral 1, or an exclamation point!
As someone with significant vision loss from a detached retina, I found it was easy to distinguish B and 8 in Atkinson, as well as other tough ones for me like "nn" and "m" or "vv" and "w," even in my damaged eye with no glasses.
Applied Design created the font and gave a great talk on the challenges and their solutions:
Image: Braille Institute