I'm one of those people. I code with 3/60 vision. Here's what I do.
I use an articulated arm for my monitor which holds it much closer to my face than any stand could while not forcing me to hunch over my desk to see.
I use larger font sizes, and spend a lot of time selecting the most comfortable available font, size, and syntax highlighting options possible. Personally, I have a lot of difficulty with contrast, so standard 'high contrast' schemes make me stabby. I tend toward darkish backgrounds with just off primary colours. This may not work for you. Be prepared to spend a lot of time experimenting. This can be frustrating, and you have my sympathy.
I use a backlit keyboard.
I probably format my code a bit differently to most people, I like to leave a lot of whitespace. Between lines, on the inside of brackets, between operators and operands, etc.
I generally have my monitor brightness set a bit lower than most people, and I also bias light.
For web browsing, I use browser plugins that allow me to zoom the text, currently zooWheel in Chrome since Firefox's kamikaze update schedule continually breaks my accessibility plugins. I used to use an FF plugin called greasemonkey to reformat frequently visited sites with custom CSS, but this turned out to be more trouble than it was worth.
I work with OS X a lot, but find it to be the most hostile environment for low - as opposed to zero - vision due to the complete lack of ability to change the colors of UI elements. There are third party hacks, but they are patchy and irritating. Apple's solution is to allow you to invert the color pallete. As the saying goes, now you have two problems. Also their cursor tends to get lost against dark backgrounds. I'm sporadically working on a software solution for this.
Linux obviously offers the ultimate in customisation, but will suck massive amounts of time if you allow it to.
You may have noticed that these are all pretty much the same kinds of things you'd do (or should do) and consider when setting up your working environment.
This is good news. As a coder, you are going to find that a lt of stuff that's severely challenging to many people with low vision is simply not a big obstacle for you. You are already well equipped to modify your tools and environment around your needs.
Hold on to that thought, because the most important thing is that much of the advice that anyone gives you, quite possibly including most of the above, simply won't be right for you. As an articulate, technically aware individual, you are in a position to try out solutions and decide what works for you. Reject anything which doesn't. Go custom where there are gaps.
Most importantly, be stubborn. You have some scary shit happening and it's going to present you with new challenges. Own them. Some days are going to be really frustrating, and you'll feel like you're losing. Go get some rest, come back, and just own the ass off them.