Topographical cornea mapping for corneal vision correction

A method for corneal topographical contour mapping and corneal reshaping for vision correction, said method comprising the steps of:

• a) directing a coherent light beam to the anterior surface of a cornea;
• b) splitting the beam so that a portion of the beam is directed to a reference object having a predetermined shape;
• c) capturing the reflected light from the cornea;
• bringing into coincidence the image of the cornea and the image of the reference surface and forming a recognizable interference pattern;
• and
• d) using the interference pattern to determine deviations of the anterior shape of the cornea from the known reference shape, wherein a topographical contour map of the anterior surface of the cornea is obtained by directing a spatially collimated light from a pulsed narrow spectrum laser to the cornea through a beam splitter, which directs a portion of the light to the cornea and another portion of the light to a reflective surface of known curvature;
• and thereafter causing reflected light rays from the cornea and from the reflective surface to interfere with each other to form said contour topographical map, which is superimposed on the image of the cornea;
• and capturing the topographical map of the cornea with a video camera
• e) determining from said captured topographical map the degree of curvature of the anterior shape of the cornea necessary for said corneal reshaping for vision correction;
• and
• f) removing a portion of tissue with a tissue removal means, from the anterior of the cornea, which portion of tissue defines a deviation of said curvature of the anterior shape of the cornea from the anterior shape of the cornea of the topographical map, to effect the vision correction wherein the tissue removal means comprises a water jet and wherein the portion of the cornea comprising the deviation of said curvature of the anterior shape of the cornea from the anterior shape of the cornea of the topographical map is shaped by a template to provide a regular surface, wherein said water jet cuts along the regular surface to effect the vision correction.

A method for corneal contour mapping, for use in producing an elevation map of a cornea and derivation maps thereof, said method comprising the steps of:

• (a) directing a spatially coherent beam of light to a beam splitter, comprising a partially transparent mirror, to produce two nominally identical beams which follow non-coincident paths;
• (b) causing one of said identical beams to illuminate an anterior surface of the cornea to be mapped;
• (c) causing the other of said identical beams to illuminate a stationary reference surface having a precisely pre-determined shape;
• (d) arranging, the beams, the anterior surface of the cornea and the reference surface, into a relative geometry such that an illuminated image of the anterior surface of the cornea overlaps an illuminated image of the reference surface, as observed through the beam splitter, wherein each of the anterior surface of the cornea and reference surface are in a position of a mirror image of the other;
• and wherein overlapping images have a superimposed interference pattern which directly measures displacement along the axis of the surface of one image from the other;
• e) constructing an elevation map of the corneal surface from the interference pattern
• f) determining from said elevation map the degree of curvature of the anterior shape of the cornea necessary for said corneal reshaping for vision correction;
• and
• g) constructing, with a computer constructing means, a derivation map of the cornea with the reshaped curvature of the anterior shape of the cornea for use in defining a deviation of the curvature of the anterior shape of the cornea between the elevation map and the derivation map, which deviation is defined for the removal thereof by a tissue removal means wherein the tissue removal means comprises a water jet and wherein the portion of the cornea comprising the deviation of said curvature of the anterior shape of the cornea from the anterior shape of the cornea of the topographical map is shaped by a template to provide a regular surface, wherein said water jet cuts along the regular surface to effect the vision correction.

A device for topographical mapping of the anterior surface of a cornea for selective removal of tissue from the anterior of the cornea;

• said device comprising:
• 1) an optical interferometric system comprising:
• i) a coherent light source, comprising a single frequency pulse laser with output pulses short enough not to be affected by eye movement and with a wavelength above 1.4 microns;
• ii) a beam splitter;
• iii) a predetermined reference shape;
• iv) capturing means for capturing reflected beams from the cornea and the reference object as the respective images thereof;
• and
• v) means for forming an interferometric pattern between the captured respective images showing a topographical map of the cornea and its deviation from the reference shape
• 2) means for determining a desired shape of the anterior of the cornea and the deviation of the desired shape from the anterior of the cornea in said topographical map for removal by a corneal tissue removal means wherein the tissue removal means comprises a water jet and wherein the portion of the cornea comprising the deviation of said curvature of the anterior shape of the cornea from the anterior shape of the cornea of the topographical map is shaped by a template to provide a regular surface, wherein said water jet cuts along the regular surface to effect the vision correction.