Why does my left eye get really hard to focus and water when Im really tired

I mean my right eye is fine, but my left eye always starts leaking tears and burns slightly and is hard to focus when I'm really tired.

YOU COULD HAVE A STIGMATISM OR HIGH BLOOD PRESSURE WATCH YOUR DIET CHECK FAMILY HISTORY FOR HIGH BLOOD PRESSURE OR DIABETESE BUT IF YOU HAVE A VISION PROBLEM ONE IS GENERALLY WEAKER THAN THE OTHER

see you optometrist...............