Name from west to east the four Great Lakes shared by Canada and the US Lake Superior, Lake Huron, Lake Erie, Lake Ontario Name the Great Lake that lies entirely in the boundaries of the US.
Definition of ophthalmology for English Language Learners. medical : the study of the structure, functions, and diseases of the eye.
Vision (Definition) Vision is a feature of a person's brain that allows him to see. He must have normal eyes, optic nerves (that stretch from the eyes to the back of his brain), and visual cortex (the vision center in the brain), in order to see properly. An ophthalmologist is a doctor specializing in vision.