| 摘要 |
A videokeratograph has a placido disc with rings concentric about a central axis, a center positioned on the central axis, and an observation opening at the center. A plurality of fixation points are positioned in the placido disc spaced from the center opening and distributed circumferentially around the central axis, whereby rings on the placido disc spaced from the center are reflected from the central zone of the cornea. A video camera positioned on the center axis behind the placido disc observes an image of the placido disc reflected from the cornea. A processor coupled to the video camera determines the shape of the central zone of the cornea. |
