Geordi may have been the only crew-member with a VISOR but he wasn't the only blind character in Star Trek to use a sensing device.
In the original series, Miranda Jones uses an advanced Sensor Web to view her surroundings. The capabilities of this piece of kit seem very similar to Geordi's VISOR. Note that neither Kirk, nor Spock show bafflement at the technology itself, just the cleverness with which it's been hidden.
MCCOY: I'm sorry, Miranda, but you must be realistic. You are blind, and there are some things you simply cannot do.
(Spock touches the decorated over-dress she always wears.)
SPOCK: Evidently a highly sophisticated sensor web. My compliments to you, and to your dressmaker.
KIRK: Yes, of course. It's the only reasonable explanation. You can't see and Kollos can't hurt you.
SPOCK: An elegant solution. but I fail to understand why you apparently try to conceal your blindness, Doctor Jones.
KIRK: I think I understand. You said it. Pity is the worst of all.
MIRANDA: Pity, which I hate. Do you think you can gather more information with your eyes than I can with my sensors? I could play
tennis with you, Captain Kirk. I might even beat you. I am standing
exactly one metre, four centimetres from the door. Can you judge
distance that accurately? I can even tell you how fast your heart is
It's fairly obvious that in the future, blindness is relatively rare. When added to the quasi-military nature of Starfleet, that would certainly explain the relatively small number of blind characters that we see.