There's a lot of conversation and debate on Tumblr about the details of Matt Murdock's blindness. This is my take on my favorite theories. Please remember that these stories exist in the world of the show and not necessarily the comics. Please read and review!
It's an evil wind that blows no good, yeah... It's a sad heart that won't love like I know it should...
Matt lay back on his bed, hands folded behind his head, with the Aretha Franklin record spinning on the dresser. The music swelled, filling the room, drowning out all the other sounds of student housing. His roommate was out with some girl, Allie or Elsie or whatever, and Matt had the place to himself.
Few sounds were robust enough to drown out background noise, and they were almost exclusively produced by vinyl records. The crackling, popping, and hissing noises the player produced provided a baseline, a kind of white noise against the city; the whirring sound a record made once it began to spin provided a second layer, killing the sounds of electronics in his room and the neighbors upstairs. If he turned the music up loud enough, Matt could drown out his own thoughts and heartbeat. It was a welcome change.
His blindness was hard to explain- the "world on fire" analogy only worked to a certain point. He knew for a fact that an MRI would insist he had some vision; that part of his brain was stimulated to the point that he could make things out in front of and around him, but the truth was that his eyes didn't work at all. His field of vision was at 0%. The combination of surroundings that led to his "impressionistic painting" of the world were compiled by taste, smell, touch, and sound. This meant it didn't matter whether his eyes were open or closed; the only time he could escape a picture of his surroundings was when he was unconscious. He didn't even have to be looking at a thing to "see" it, which gave him an unusually complete and frankly overstimulating image of the world.
Laying there, listening to that record at full blast, Matt got a rare glimpse of peace and quiet. His sense of the air in the room- heat rising, the smell of a neighbor's dinner, swirled about him like a Van Gogh night scape, an abstract peace. He transcended his usual relaxation and floated into a place of true quiet.
In spite of what Stick had taught him, or maybe because of it, Matt's life was particularly exhausting. Did he really need the cane? Not if he focused. But that counted him out of so many things- walking and talking was particularly difficult, for instance. Tuning out, focusing, isolated him in the world. The whole picture required use of his whole brain. Sometimes he just didn't have that during the day.
Matt debated explaining this to his new roommate, and ultimately decided against it. In the month they'd lived together, they'd become fast friends. Foggy was a little heavy-footed, with long hair that brushed his shoulders and a deep and abiding love for the band Phish. He was unlike anyone Matt met in undergrad (though, after a decade in an orphanage, he'd jumped at the idea of a single room), immediately helpful and excitable. It was nice to have someone who grew up in Hell's Kitchen with him in the Ivy League. Foggy was a scholarship kid, unafraid to tell pompous daddy's boys to get over themselves. He studied hard and played harder. He was in the habit of explaining other people's nonverbals (shrugging, winking, waving), and Matt knew that if he told him about the whole sensing-air-currents echolocation thing, he wouldn't understand.
Matt had never had a friend like Foggy. Not ever, even once in his life. Matt spent his life holding things back, while Foggy lived in a world of broad self-disclosure. Matt didn't need another cold acquaintance; he liked Foggy and his enthusiasm.
He'd explain his talents to Foggy eventually. He'd just wait until they knew one another a little bit better.