The legal status of anabolic steroids varies from country to country. In the ., anabolic steroids are listed as Schedule III controlled substances under the Controlled Substances Act , which makes the possession of such substances without a prescription a federal crime punishable by up to seven years in prison.  In Canada, anabolic steroids and their derivatives are part of the Controlled drugs and substances act and are Schedule IV substances, meaning that it is illegal to obtain or sell them without a prescription. However, possession is not punishable, a consequence reserved for schedule I, II or III substances. Those guilty of buying or selling anabolic steroids in Canada can be imprisoned for up to 18 months. Importing or exporting anabolic steroids also carry similar penalties.  Anabolic steroids are also illegal without prescription in Australia,  Argentina, Brazil, and Portugal,  and are listed as Schedule 4 Controlled Drugs in the United Kingdom.
They reduce your immune system response, not boost. I do not know about eye problems, but steroids for my lung problem were a lifesaver for me, I had inflammation 4+ months out of each year. Finding the source of my problem and working on that would have taken a long time considering the inflammation cycle I was in, and breathing is important (as is stopping possible eye damage caused by your own body). I was able to stop using the steroids b/c the inflammation cycle I was in was interrupted by dampening it for a short time with the medication. I think your biggest question should be "how long do I need to take these?" Long term steroids can cause major immune system problems, whereas in the short term they can be very helpful. I am grateful for medical science in the handling of acute problems. Again....I don't know about eyes tho.
If you're going to use any injectable gear, then of course you're going to need some "darts." You can pick up syringes at your local pharmacy unless your state has certain restrictions. Also, you can purchase needles online. Just do a little searching around and you'll find several places that'll hook you up. Syringes will run you around 50 cents apiece. Note that it'll be more difficult to obtain needles (at least from the larger, more "legit" companies) if you live in California and Illinois. You'll usually need a doctor's prescription in those states. Still, if you look around enough, you can get what you need.