Topography is a computer assisted diagnostic tool that creates a three-dimensional map of the surface curvature of the cornea. The cornea is responsible for about 70 percent of the eye's focusing power. An eye with normal vision has an evenly rounded cornea, but if the cornea is too flat, too steep, or unevenly curved, less than perfect vision results. The advantage of corneal topography is its ability to detect irregular conditions invisible to most conventional testing. Corneal topography produces a detailed, visual description of the shape and power of the cornea. This type of analysis provides fine details regarding the condition of the corneal surface. These details are used to diagnose, monitor and treat various eye conditions. They are also used in fitting contact lenses and for planning surgery, including laser vision correction. For laser vision correction the corneal topography map is used in conjunction with other tests to determine exactly how much corneal tissue will be removed to correct vision and with what ablation pattern.