Like many users of the internetz, I too have a vision problem. It's -2.50 / -2.25 based on the last checkup which was months ago.
Vision will have a great impact on your play in Starcraft whether you'd like to believe it or not, and the way you approach your Vision whilst playing Starcraft will have an impact on your life.
There are three main conditions that your average Starcraft II player may have and they are Myopia, Hyperopia and Astigmatism, all of which can be treated with eyeglasses / contact lens.
With stronger vision (or weaker conditions), it is possible to play / use the computer without the use of eyeglasses / contact lens (From a myopia standpoint, anything greater than ~-2.50). If you are able to comfortably use your computer for hours without the use of glasses / contact lenses, I strongly reccomend that you do not use them as they are not perfect in correcting your eyes and the effect that they have works both ways. What I mean by this is that if you aren't able to see things that are far away, they will enhance whatever you see to be able to see clearly. Although they help you see things that are far away, they also make it more difficult to see things that are closer to you - your eyes have to strain extra hard to focus on something closer. This in turn will have an overall effect on you causing you to be more tired the longer you use them. If you wear / have worn contact lenses, you'll know what i mean. Wear them and go out for the whole day and when you get home, try to remember what it feels like when you take them off. The next day, wear them and play Starcraft all day - when you take them off, your eyes will feel worse due to having to strain to see something close up. This will actually cause your vision to become worse!
With weaker vision (or 'stronger' conditions), it will be pretty much impossible to use the computer without glasses / contact lens (I'm talking about ~-3.00 and less) unless you're really close up/using a retarted resolution on your monitor. In these cases, glasses / contact lenses are kind of a "duh!".
If you are unable to use the computer comfortably without glasses, the best thing to do is to have a second pair of glasses / set of contact lenses which will allow you to see anything upto your computer very clearly. So for example, if your vision is -5.50/-5.50, order glasses with a power of like -4.00/-4.00 (or use your old, weaker glasses). You will still be able to see clearly without as much of a backdraw on your energy levels. If you cannot tolerate glasses and must have contact lenses, just buy one extra packet of weaker contact lenses for every three or four packets you buy for an edge during those days where you wake up, eat breakfast and head on for a 8 hour Starcraft marathon.
Another problem with wearing strong glasses / contacts is that your vision may suffer even more if most of your work is at the desk (this is especially relevant at teenage years where your body is still developing) and so having an extra pair is the smart thing to do.
TLDR: Get weaker glasses / contact lenses if you REALLY require assistance whilst playing Starcraft / using the computer, otherwise, dont use them as they are slightly detrimental to your health.
Day[9] #123: Try to squeeze a little bit more advantage, a little bit more juice ... :D