For me, this is the worst case scenario... a permanent blindness... There is a freaking (and absolutely harmless) trick that you can do and experiment a total blindness situation for a few minutes. This trick is explained in mind hacks like this:
First, hold your eyeball perfectly still. You could use calipers to do this, or a drug that paralyses the eye muscles, but my favourite method is to use my thumb and index finger. Using the sides of your thumb and finger, press on the bone of the eye socket, through your upper and lower eyelids. Do this gently. Try it with one eye first, closing the other eye or covering it with your hand.
With your eye fixed in position, keep your head still and soon you will experience the strangest thing. (You will have to stop reading at this point. I don 19t mind. We will pick up when you have finished). After a few seconds the world in front of you will fade away. As long as you are holding your eyeball perfectly still, you will very quickly discover that you can see nothing at all. Blink, or move your head, let go of your eye and the world will come back.
Do this, and within seconds your vision will start to black-out until you won't see anything. What is really happening? Actually, your eye is sensing the exact same pattern of light on the retina. Since this pattern is not changing, the photo-receptors start sending messages to the brain less often. As time passes, less and less information is passed tot he brain, until the brain receives no info at all.