A blind chihuahua is able to navigate her world after learning verbal cues such as "careful" or "walk straight".<br /><br />Grace, 12, started to lose her eyesight two years ago after her owner Shelby Salmela, 30, noticed her right eye had become enlarged and watery.<br /><br />After a series of tests, vets diagnosed Grace with glaucoma in both of her eyes.<br /><br />Glaucoma is a chronic eye disease that damages the optic nerve. <br /><br />The condition in her right eye was so severe that it had to be removed.
