لماذا يلبس الأعمى نظارة سوداء وهو لا يرى ؟

Dear reader,

I am going to try very hard to be polite here. It isn't easy because this question makes my blood boil. I am often harassed by people who take exception to the combination of my white cane, my glasses and the printed book that I am reading on the train. But since you asked, I will try to clear this up for once and for all. Read this next sentence very carefully please.

Most "blind people" can see some.

There are people who are totally blind. Some of them where glasses. Some reasons might be 1. to cover disfigured eyes and thus gain a bit in social acceptance, 2. to protect their face from branches and other obstacles and 3. to let other people know they can't see (again in order to avoid social problems and as a traffic safety measure).

However, 90 percent of legally blind people can see something, even if just light. Those who can see only light are often light-sensitive and bright light can cause pain. If they can't see much beyond light, they will rarely have a warning when bright light is coming. So, dark glasses are a real necessity.

And then there are the rest of us, i.e. most people who are legally blind who can actually see some but not much. We often wear glasses in order to improve our vision. There are legally blind people with an extremely narrow field of vision (sometimes called tunnel vision) who can otherwise see pretty well but only in a small area. A person with that kind of vision problem may or may not need glasses.

Then again many legally blind people are simply extremely nearsighted. This is my specific vision impairment. I am so nearsighted that my eyes focus about an inch from the lens. Very heavy glasses push this point out to about two inches, which may not sound like a big improvement but it significantly improves what I can see at ten feet. Everything at ten feet is still really blurry either way but without glasses it is just a massive blur with no distinction. With glasses there are lumpy fuzzy large objects. So, glasses make a big difference. Contact lenses are actually more effective in my case (explaining why would take a very long scientific explanation of optics and the distances between lenses). But the extraordinarily thick contact lenses I wear tend to damage your cornea, so I can't wear them very often. Thus the glasses.

And just to complete the explanation (although I know you aren't the irate train conductor from yesterday who didn't believe that I'm legally blind because I was reading The Little House in the Big Woods in print to my daughter on the train with my white cane propped on my knee) I can see reasonably well at two inches. That is why I was reading the book so close. (No, please do not mash the book into my face and claim that you are helping me get it closer as so many people have or I will stop being polite.) I cannot, however, see the gray-on-gray steps on the train and if I don't use a white cane (or a good memory and some echolocation) I might trip. I also use the white cane to tell you why my eyes are a bit squinty and why they move erratically. The fact that I have a white cane will tend to make you realize that I probably can't see well. Otherwise, most people immediately assume I have a mental or developmental disability. Given the choice, I prefer the nasty social things most people do to blind people over the nastier social things most people do to people with developmental disabilities. So, even though I can usually get around pretty well (even over those gray-on-gray steps) with echolocation and memory, I have started carrying a white can in order to avoid endless explanations and ostracism.

Ironically, the other most common reason I am harassed in public over my vision impairment is when I wear contact lenses instead of glasses. I can't count the times a complete stranger has lectured at me about how I need to go to the eye doctor and get glasses, when they see how close I'm holding my book. I have heard many people insist that glasses can always "cure" any nearsightedness. I have tried to explain the principles of optics to them and the fact that nearsightedness can only be corrected so far and that, in any case, there are these wonderful new things that came out... oh... about fifty years ago called "contact lenses" and I'm wearing a state-of-the-art example that works far better than any glasses.

The point of all this and the answer that you didn't ask for is this. Please, dear reader, don't bug people about their glasses or lack there of or their cane or lack there of or their wheelchair or their hearing aid or any such thing or lack there of. It is their device and their responsibility. If they are your friend (or on Quora) and you're curious, they'll probably be happy to explain, if you ask politely. The fact that someone has a disability card that says they are blind and yet they don't have a white cane and they either do or don't wear glasses does not mean that they have forged the disability card. It means they have good orientation and mobility skills, some ability with echolocation and rhino skin when it comes to the social world. Doctors are in charge of diagnosing vision problems and helping people determine what sorts of glasses or other optical aids they need. It is not your job to attempt to give such advice on the subway or in the workplace or at school or anywhere, unless you're medical vision specialist (in which case I hope you're laughing by now).