Well, this part of my question I can at least answer now: there is also a yellow armband with three black dots that I’ve seen in Europe. I think that awareness and adoption of this symbol is very low, though. I very rarely see blind people wearing it; most of them just use a white or red-and-white cane, usually without sunglasses. A lot of German pedestrian crossings have this symbol emblazoned on a special signal box, which means that an audio signal can be activated by pressing a concealed button on the underside of the box. But the general public seems to have no clue what this is for. Practically every day I see sighted people touching the front of the signal box (which has no effect) or pressing the hidden button underneath, mistakenly thinking that it’s necessary to trigger the traffic lights.
In Fielding’s case, that probably didn’t apply. It is now known that he was blinded in a botched eye operation by the surgeon, James Wilkie.
All I know is that in the 20th (and21st century) people signal over the phone that they have a headache by using a hoarse voice (because you can’t do ‘headache’ over the phone). 
Or per Langston Hughes:
That Justice is a blind goddess
Is a thing to which we black are wise:
Her bandage hides two festering sores
That once perhaps were eyes
Given that we know:
- portraits of this period often use symbols to say something about their subject
- a blind person may have worn a black bandage over their eyes
- Sir John Fielding, even after he was blinded, was a prominent magistrate, known for the soundness of his judgment and the fact that he could recognise criminals by their voices alone
…I suggest that the band being raised above his eyes for the portrait might symbolise his clear-sightedness in the sense of clarity of discernment - and perhaps even a heightened sense of this - despite his disability.
In my state all pedestrian crossings are audio-enhanced. Some click all the time, some only when the pedestrian crossing button is pressed.
I’ve known this to baffle foreigners – they can’t get their head around the idea that street lights and zebra crossings all make a noise — but it seems very ordinary to those of us who live here
(You can, by special request, get the sound turned off if it’s near your home and bothers you at night. But If a sight-handicapped person asks for it to be turned on again, that has priority)
A greatAustralian design for the same thing. The central strip vibrates (it’s the middle of the arrow shaft) and is used for visually and hearing impaired pedestrians to know when the crossing lights are on.
Sir John’s eyes are not the only things to have changed in his portrait over the last 13 years.
Alright, I don’t know why this zombie thread is revived, but I’m a professional artist, professional art nerd, with a degree in art nerdery. It’s not often something on the dope is this far in my wheelhouse.
Mostly other people have touched on the answers, but I can expand on some of it.
First, art such as this painting is usually predicated on some manner of art historical symbolism, which is more or less well defined and established as a specific vocabulary.
Going through my books on art history and symbology helped illuminate blindness and the blind depicted in art (Signs and Symbols in Art by Mark O’Connell yielded the best results, tho Hidden Symbols in Art by Sarah Carr-Gomm and a few other books had some insights).
As mentioned, it’s well established that the blind or blindness is art is usually depicted by a blindfold. This can indicated either willful blindness or covering of injury or unsightly cataract eyes or empty sockets (just look how Pieter Bruegel portrayed the blind).
Most “blindness” portrayed in classical art falls under “willful” or moral blindness: The Rota Fortunae often depicts FATE as being morally and spiritually blind, as fate favors none over any other. Blind Justice is another well known trope.
In masonic/freemason symbolism, the blindfolded man (depicted in my book with literally a black band around his eyes) symbolizes spiritual blindness–removing the blindfold (as initiates will eventually do) indicates spiritual illumination.
Bringing it back to the portrait series of Sir John Fielding, Hone invoked the classical trope of “moral blindness” and the depiction of the removal of the blindfold to represent a sense of enlightenment (relating to Fielding’s renown moral blindness regarding the law, in spite of his literal blindness. He was said to know the voice of criminals and able to pick them out based on that alone). Hone painted a series of these paintings, starting with this miniature reproduction with Fielding and his family.
According to Georgina Cole, Hone:
Finally, regarding the literal painting the OP is commenting on, it is said that:
So this is not some established direct symbolism–a black headband meaning you are blind, but rather a lifted blindfold–which is a VERY well established art-historical symbol representing blindness–shown to show that this blind man’s blindness is not an impediment but rather a source of enlightened, even-handed enlightenment.
The statue of Justice on the Irish Law Courts from the British period isn’t blindfolded. She faces towards the Castle (seat of the Viceroy), rather than looking out over Dublin.
All of which led to this little ditty:
*There She stands,
Above her station,
With her face to the Crown,
And her arse to the Nation.
*
I’m not an expert on this aspect, but over the years I recall seeing multiple old paintings of blind people and the give-away was that they had a bandage/band around the head covering the eyes to indicate the affliction - even poor people and especially beggars. I don’t recall any colour being significant. I would expect that the guesses above are correct - that he would (sometimes?) wear this around his eyes, but for a portrait (as opposed to an allegory or story painting) the full face was preferable so it was simply pushed up, to indicate that the problem existed while not blocking out a significant part of the face in the portrait.
Perhaps the bandage is analogous to the dark glasses often worn by blind people today - again, a superfluous but symbolic attribute.
Thanks so much, dontbesojumpy, for your edifying post!
Yes, that was very interesting.
I absolutely mangled that last sentence and missed the edit window because it was Thanksgiving…the GF wanted more pie…the puppy was being unruly…there was alcohol running afoul…and other excuses.
I’d like to take another swing at it–
So this is not some established direct symbolism–a black headband meaning you are blind–but rather a *lifted *blindfold, which is a VERY well established art-historical symbol representing blindness. It is portrayed to distinguish that *this *man’s blindness is not an *impediment *but rather a source of enlightened, even-handed judgement.