Researchers have said that computer simulations that map the way tears move across the eye's surface could one day lead to the treatment for dry eye - a burning gritty condition that can impair vision and damage the cornea. To understand dry eye Kara Maki assistant professor in Rochester Institute of Technology's School of Mathematical Sciences had to begin with the physics and chemistry of tears. Tear film consists of a layer of water sandwiched between an oily layer of lipids on the outside to prevent evaporation and an inner mucous layer to spread the water over the eye. Maki developed a mathematical model