My suggestion is to use paper / cards & sounds.
Have everyone make their estimates with their cards / paper. Then everyone shows their estimate at the same time.
At this point the visual members look around and you even hear folks say, hmm, 5,5, 2, hey bob, what's up with your 2? etc
So expand a little more on that verbal part.
Have everyone make their estimates, show their card / paper and very quickly have everyone (in turn) say their numbers. Do that one-by-one (but quickly) so within 2-3 seconds you hear 5,2,5,4,5,5. The visually impaired person will then know the range of values and also who's voice goes with with ticket which is probably essential (and also helps avoid the need for everyone to sit in the same spot each time).
Similarly if folks change their estimates during discussion make sure they verbalize any changes.
To avoid the all-critical 'influenced by' consider having members write down their initial choices on scraps of paper (or use playing cards). Folks would choose the intended card initially and put the others down. Then, when the 'going around' is done people would hold up their initially selected and only card AND say the points at that moment.
This is pretty close to what you are doing, the main change being to have each member verbalize their choice themselves, rather than you reading them all "for Bob" - which makes the "read for Bob" a distinct process which is not good socially for Bob. It singles him out as being different and having special needs.
Try to make these techniques integral to your flow so that an outsider wouldn't notice differences easily. Avoid any sort of "now lets 'say' our choices' or 'whoops I forgot about Bob'. You can forget but if you do just say the number without discussion and apology and move on immediately.
Braille cards are good but remember that they make "Bob"'s impairment stand out, new/visiting team members have to be coached, Bob can't work on other scrum teams without them learning how the cards will be used. All of which is a lot of focus for Bob which is one of the things you want to avoid for someone with special needs. This is why I think the verbal approach avoid much of that.