Researchers at McGill University in Montreal discovered that Tetris could be used to help correct amblyopia, commonly known as a "lazy eye." Using head-mounted video goggles, the treatment made the lazy eye focus on the falling shapes, which the researchers made high contrast, and to have the dominant eye focus only on the background grid, which was rendered in low contrast. Patients using this method showed four times the improvement rate in their vision, as opposed to those using the traditional eye-patch treatment.