Well, it is possible to make yourself temporarily blind if you've got low enough blood pressure and stand up quickly! Get a heater and a blanket, or just a heated blanket, and stay horizontal for a while. Once you're all warm and maybe a little tired, basically just a degree or two from throwing off the blanket, throw it off and stand up as fast as possible. Avoiding food for while will also make the effect stronger! I've found that total blindness tends to also come with hearing loss (until the blood comes back in haha) so you get both at once!

If you're not lucky enough to have low enough blood pressure, get a friend to hug you as tight as possible as soon as you stand. If you do have low blood pressure, this combination is a quick ticket to passing out, so don't do it regularly. But if you've got normal to higher blood pressure, I would expect this to be enough temporary blood loss to the head that you'll lose a sense or two. I'm afraid I only have experience with low normal and low blood pressure so your mileage may vary on effectiveness. Ensure you've got a soft surface to land on in case it goes wrong.

It is really hard to describe loss of vision for sure. The lack of vision is a little panic inducing when you open your eyes wide and nothing happens. It feels dark, like its black, but its not actually black. Maybe just the kind of color that you see as vague patterns when you squeeze your eyes shut tight in the dark, but even then its not quite right.

But I disagree with sight being the most important sense. Importance simply depends on your environment. Is it important in our society? Absolutely! But that's because we have chosen to focus on it collectively. I think its all relative, though I believe a lack of touch and/or pain is perhaps the most damaging across the board. Without pain, it's hard to detect damage and difficult to feel encouraged to avoid it. Lack of sight, sound, smell, or taste is a challenge, but rarely deadly alone. But when touch/pain is gone? Life expectancy tends to shrink simply because you no longer have a warning system to tell you when something has gone wrong!