Well, it is a condition in which, whenever you look at any object, you see its two images rather than one. This is also referred to as double vision. It is totally different from blurred vision, in which you see a single blurry and unclear image of an object. It can severely harm your decision-making capacity and quite often, if you insist on driving, put others as well as yours life at risk. Normally, when we look at an object, the muscles of the eyes co-ordinate with each other to focus on the same object. The brain on receiving information from the eyes processes it and come up with a 3 - dimensional image. But, what if there is lack of muscle coordination, due to some reason. The eyes cannot focus on the same object and this leads to double vision. There are many reasons which can cause the double vision, such as alcohol, stress, and injury. So you should pay more attention to it.
I have experienced this. After I have worked before the computer continuously for over a week, I suddenly feel the things I see be in blurry in the morning after I wake up. The one thing I see looks like two parts, with the double images. Then the doctor tells me that my sudden blood pressure change causes this.
Well, when I was an eighteen year old teenager, I was absorbed in video games and cyber games and could not pull myself out of them, and my vision was pretty bad. Sometimes I will experience red eyes, bloodshot eyes and even double vision when I was too tired after playing games. It was just like seeing two identical worlds and you are gonna be dizzy! Generally speaking, as long as you see things vague and cannot focus on them, then, probably you have double vision and you need medical care.