Apparatus for determining cornea contour

Claim 1

In an apparatus for determining the contour of the human cornea comprising a target structure, means for illuminating the target structure for developing light patterns on eye surfaces, means for reflecting an image of said light pattern to a viewing area, and a camera positioned at said viewing area for providing a photographic record of the pattern, the improvement in said target structure comprising a first hollow shell having a generally cone-shaped configuration, a relatively small opening defined at the small diameter end of said first shell, the opposite end of said shell defining a large diameter base portion, a second hollow shell defining a corresponding large diameter base portion at one end, said second shell defining an inwardly extending wall, means for securing the respective base portions of said shells together, means for positioning the head of the person being tested whereby an eye of the person is positioned adjacent to said small diameter end of said first shell and substantially centrally of said opening in said first shell, said first shell operating as a light guide for transmitting light from its base portion toward its small diameter end, and including a plurality of separate, light transmitting, spaced apart gaps defined by each of said shells, the arrangement of said gaps determining the light pattern projected onto an eye when said target is illuminated, said apparatus further including stepped portions defined on the interior surfaces of each of said shells, at least some of said gaps being located on said stepped portions, the stepped portions of said first shell being formed by progressively reducing the wall thickness of said first shell in the direction toward the small diameter end thereof, and the stepped portions of said second shell being formed by means of bends in the shell wall, and wherein saId target is formed of a transparent plastic material, at least one surface of the target being covered with an opaque coating in all areas except in the positions of said gaps, and including a light reflecting coating formed on the exterior of at least a portion of the target structure whereby said portion of the target structure provides a light guide for directing light to the gaps in said portion.