| 摘要 |
A method and apparatus in which a predetermined index is projected onto the cornea of an eye to be examined and the shape of the cornea determining the refractive power, the degree of astigmatism, the direction of astigmatic axis, etc. of the cornea is measured from the general elliptical shape of the image of the index reflected by the cornea. Independently of the center of the ellipse, arbitrary position coordinates of at least five points of the image reflected by the cornea are detected, whereby the elliptical shape is calculated without enhancing the alignment accuracy in a plane perpendicular to the optical axis. The image reflected by the cornea may be electrically detected by position detects such as CCDs, whereby automation of the measurement is provided, coupled with the later signal processing. A strobo light is used for the projection of the index. Further, the shape of the cornea is obtained so that no measurement error may occur depending on a variation in operating distance, that is, without enhancing the positional accuracy in the direction of the optical axis.
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