Why do my eyes water and burn when I lay down?

I do use a computer a lot (I'm a college student), but this issue predates my heavy computer usage. I also know I have dry eyes, but it gets so much worse when I lay down. Normally, my eyes will water intermittently throughout the day (but they don't burn), and my optometrist has tried everything. At this point it's just something I have to learn to deal with. Wearing my contact lenses has helped a bit during the day, but at night I take them out (obviously). Often, I'll be laying in bed, either reading or talking on the phone or doing homework, wearing my glasses, and my eyes will start to water uncontrollably. It gets to the point where I have to use a towel to wipe my eyes, because a tissue would tear with all the liquid. It also burns terribly. It only subsides when I take my glasses off and go to sleep, when my eyes are closed. I don't know what to do about this issue, and my optometrist has been no help. I know it has to be something other than just dry eyes, because it's nothing like the issues I have during the day. And I spend a lot of time on the computer, not just in the evenings, but even if I'm in a dark room sitting in a chair at the computer I don't have this problem. It only happens when I'm laying down.

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