The most common cause of dry eye is lack of tears. In order to stimulate tears, cut up a raw onion and let the vapours rise into your eyes for a couple of minutes.
At bedtime and in the morning, rub the palms of your hands against each other and place the balls of the palms on your eyes. Repeat ten times. Also use pure rose-water drops one in each eye at bedtime. Twice a day, massage the inner corners of the eye sockets very gently with your thumbs to help stimulate the tear glands.