Methods and apparatus for laser sculpture of the cornea

Claim 2

Sculpture apparatus for making a uniform-depth constant-area ablated removal of corneal tissue in preparation for reception of a corneal transplant in an optically used area of the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam on a central axis of beam delivery to said area, the intensity distribution of laser-beam projection on said axis exhibiting substantially the same profile of fall-off in all radially outward directions from said axis, whereby for a given exposure of only said beam to said area, a curvature-decreasing change is effected at the anterior surface of the cornea, with depth of tissue-ablating penetration greatest at the center of said area and with penetration depth exhibiting substantially the same profile of fall-off in all radially outward directions from the center of said area, and controllable means for variably limiting the sectional area of said beam at impingement with the cornea, said controllable means including at least one indexible mask having a plurality of annular mask apertures of progressively changing inner radius, and control means connected to said laser means and to said controllable means for so controlling successive exposures via a succession of indexed mask apertures as to produce a curvature-increasing change, to the extent that a net substantially uniform depth of ablation of corneal tissue is achieved to said greatest depth over at least said optically used area.

Claim 3

Sculpture apparatus for making a uniform-depth constant-area ablated removal of corneal tissue in preparation for reception of a corneal transplant in an optically used area of the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam on a central axis of beam delivery to said area, the intensity distribution of laser-beam projection on said axis exhibiting substantially the same profile of fall-off in all radially outward directions from said axis, whereby for a given exposure of only said beam to said area, a curvature-decreasing change is effected at the anterior surface of the cornea, with depth of tissue-ablating penetration greatest at the center of said area and with penetration depth exhibiting substantially the same fall-off in all radially outward directions from the center of said area, and controllable means for variably limiting the sectional area of said beam at impingement with the cornea, said controllable means including (a) a zoom-lens system and (b) at least one indexible mask having a plurality of annular mask apertures of progressively changing inner radius, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of a plurality of indexed apertures of said mask as to produce a curvature-increasing change, to the extent that a net uniform-depth ablation of corneal tissue is achieved to said greatest depth over at least said optically used area.

Claim 4

Sculpture apparatus for making a uniform-depth constant-area ablated removal of corneal tissue in preparation for reception of a corneal transplant in an optically used area of the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam on a central axis of beam delivery to said area, the intensity distribution of laser-beam projection on said axis exhibiting substantially the same profile of fall-off in all radially outward directions from said axis, whereby for a given exposure of only said beam to said area, a curvature-decreasing change is effected at the anterior surface of the cornea, with depth of tissue-ablating penetration greatest at the center of said area and with penetration depth exhibiting substantially the same fall-off in all radially outward directions from the center of said area, and controllable means for variably limiting the sectional area of said beam at impingement with the cornea, said controllable means including (a) a zoom-lens system and (b) at least one indexible mask having a plurality of annular mask apertures of progressively changing inner radius, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of a plurality of indexed apertures of said mask as to produce a curvature-increasing change, to the extent that a net uniform-depth ablation of corneal tissue is achieved to said greatest depth over at least said optically used area.

Claim 5

Sculpture apparatus for operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional are of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum optically used area to be ablated and being symmetrical with respect to an axis of beam-projection to the cornea, and flux-density distribution across the beam-projection axis being at maximum near the beam-projection axis and diminishing with distance away from the beam-projection axis; said controllable means including; (a) at least one indexible mask having a plurality of circular mask apertures of progressively changing radius; (b) at least one indexible mask having a plurality of annular mask apertures of progressively changing inner radius; and (c) control means connected to said laser means and to said controllable means for so controlling the successive use of said masks as to produce a uniform-depth ablation of corneal tissue at least over said optically used area.

Claim 6

Sculpture apparatus for operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional are of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum optically used area to be ablated and being symmetrical with respect to an axis of beam-projection to the cornea, and flux-density distribution across the beam-projection axis being at maximum near the beam-projection axis and diminishing with distance away from the beam-projection axis; said controllable means including; (a) at least one indexible mask having a plurality of circular mask apertures of progressively changing radius; (b) at least one indexible mask having a plurality of annular mask apertures of progressively changing inner radius; and (c) control means connected to said laser means and to said controllable means for so controlling the successive use of said masks as to produce a uniform-depth ablation of corneal tissue at least over said optically used area.

Claim 7

Sculpture apparatus according to claim 3, in which successive of the annular mask apertures are characterized by outer radii which progressively expand outwardly of the maximum radius of the circular-mask apertures.

Claim 8

Sculpture apparatus according to claim 3, wherein said controllable means further includes at least one indexible mask having a plurality of elongate rectangular apertures of progressively changing width, and selectively operable means for orienting the said rectangular apertures for successive rectangular-spot delivery wherein the elongation extends diametrically through the axis of beam projection to the cornea and at an angular orientation to effect an astigmatism correction.

Claim 9

Sculpture apparatus for operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum optically used area to be ablated and being symmetrical with respect to an axis of beam-projection to the cornea, and flux-density distribution across the beam-projection axis being at maximum near the beam-projection axis and diminishing with distance away from the beam-projection axis; said controllable means including: (a) at least one masking means for producing circular-spot delivery of progressively changing radius; (b) at least one masking means for producing annular-spot delivery of progressively changing inner radius; and (c) control means connected to said laser means and to said controllable means for so controlling the successive use of said respective masking means as to effect at least a predetermined depth of stroma-penetration over the entire optically used area of the cornea as well as a predetermined anterior-surface contour.

Claim 10

Sculpture apparatus for operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum optically used area to be ablated and being symmetrical with respect to an axis of beam-projection to the cornea, and flux-density distribution across the beam-projection axis being at maximum near the beam-projection axis and diminishing with distance away from the beam-projection axis; said controllable means including: (a) at least one masking means for producing circular-spot delivery of progressively changing radius; (b) at least one masking means for producing annular-spot delivery of progressively changing inner radius; and (c) control means connected to said laser means and to said controllable means for so controlling the successive use of said respective masking means as to effect at least a predetermined depth of stroma-penetration over the entire optically used area of the cornea as well as a predetermined anterior-surface contour.

Claim 11

Sculpture apparatus according to claim 6, in which said masking means for producing annular-spot delivery is further characterized by production of outer radii which progressively expand outwardly of the maximum radius of circular-spot delivery.

Claim 12

Sculpture apparatus for curvature-correcting operation upon the anterior surface of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being limited per unit time to ablate but a fraction of a predetermined maximum depth of ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of the apertures of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement of the cornea with an accompanying diopter change in the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, the number of mask apertures and the relation of area change between one and the next mask aperture through the progression of area change being selected for limitation of requisite zoom-lens magnification to the range 1:1.414 or less, for each of the indexed positions of said mask, whereby the variation in energy density at the cornea is within the range 1:2.

Claim 13

Sculpture apparatus for curvature-correcting operation upon the anterior surface of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being limited per unit time to ablate but a fraction of a predetermined maximum depth of ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of the apertures of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement of the cornea with an accompanying diopter change in the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, the number of mask apertures and the relation of area change between one and the next mask aperture through the progression of area change being selected for limitation of requisite zoom-lens magnification to the range 1:1.414 or less, for each of the indexed positions of said mask, whereby the variation in energy density at the cornea is within the range 1:2.

Claim 14

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising pulsing laser means for producing a succession of tissue-ablating pules in an output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being such that corneal-tissue ablation per pulse is but a fraction of desired maximum ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so variably controlling zoom-lens setting for each of an indexed plurality of apertures of said mask as to deliver a plurality of pulses in the course of zoom-lens variation for each of said indexed plurality of mask apertures whereby to achieve a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, the number of mask apertures and the relation of area change between one and the next mask aperture through the progression of area change being selected for limitation of requisite zoom-lens magnification to the range 1:1.414 or less, for each of the indexed positions of said mask, whereby the variation in energy density at the cornea is within the range 1:2.

Claim 15

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising pulsing laser means for producing a succession of tissue-ablating pules in an output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being such that corneal-tissue ablation per pulse is but a fraction of desired maximum ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so variably controlling zoom-lens setting for each of an indexed plurality of apertures of said mask as to deliver a plurality of pulses in the course of zoom-lens variation for each of said indexed plurality of mask apertures whereby to achieve a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, the number of mask apertures and the relation of area change between one and the next mask aperture through the progression of area change being selected for limitation of requisite zoom-lens magnification to the range 1:1.414 or less, for each of the indexed positions of said mask, whereby the variation in energy density at the cornea is within the range 1:2.

Claim 16

Sculpture apparatus according to claim 8 or claim 9, in which the mask apertures are circular and or progressively changing radius, whereby to effect a relatively smoothly profiled myopia-correcting diopter change.

Claim 17

Sculpture apparatus according to claim 8 or claim 9, in which the mask apertures are elongate rectangular and of progressively changing lateral width, and selectively operable means for orienting the elongation axes of said apertures in accordance with a predetermined orientation of desired astigmatism correction, whereby to effect a relatively smoothly profiled cylindrical diopter change.

Claim 18

Sculpture apparatus according to claim 8 or claim 9, in which the mask apertures are circularly annular and of progressively changing inner radius, and in which said mask apertures are of outer radius which when projected to the cornea via said zoom-lens system is greater than that of the maximum curvature-correcting area to be ablated, said controllable means further including continuously variable-iris means for varying said outer radius, said control means so coordinating iris aperture with zoom-lens setting and with currently indexed mask aperture as to effect a relatively smoothly profiled hyperopia-correcting diopter change within said maximum curvature-correcting area and also to effect a relatively smoothly beveled annular zone of blending slope outwardly from said area of diopter-changing curvature correction.

Claim 19

Sculpture apparatus according to claim 8 or claim 9, in which the mask apertures are circularly annular and of progressively changing inner radius, and in which said mask apertures are of outer radius which when projected to the cornea via said zoom-lens system is greater than that of the maximum curvature-correcting area to be ablated, and a further circular mask aperture interposed between said controllable means and the location of beam delivery to the eye, said further mask aperture being of such radius as to limit beam delivery to the radius of said area of diopter-changing curvature correction.

Claim 20

The sculpture apparatus of claim 8 or claim 9, in which said controllable means includes shutter means operable to preclude laser-beam impingement at the cornea, said control means being operative to preclude laser-beam impingement at the cornea upon completion of beam exposure for each utilized mask aperture and for the period (1) of mask-indexing into the operative position of the next mask aperture in said progression and (2) of zoom-lens resetting for operative use of said next mask aperture.

Claim 21

Sculpture apparatus according to claim 8, in which said control means is connected to determine a different time of beam exposure and of zoom-lens utilization for operative use of each of a succession of mask apertures of said mask.

Claim 22

Sculpture apparatus according to claim 9, in which said control means is connected to determine a different number of pulses of beam exposure for each of a succession of apertures of said mask.

Claim 23

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being limited per unit time to ablate but a fraction of a predetermined maximum depth of ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of the apertures of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said mask being one of a plurality of circular discs which are in axially separated array and which are so connected to said control means as to be separately indexible about the same axis of index rotation, each of said discs having a differently characterized progression of apertures of varying beam-transmitting sectional area, and one of the apertures of each disc having an opening area as to avoid beam-section limitation upon the beam-section-limiting ability of any aperture of any other disc of said plurality.

Claim 24

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being limited per unit time to ablate but a fraction of a predetermined maximum depth of ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of the apertures of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said mask being one of a plurality of circular discs which are in axially separated array and which are so connected to said control means as to be separately indexible about the same axis of index rotation, each of said discs having a differently characterized progression of apertures of varying beam-transmitting sectional area, and one of the apertures of each disc having an opening area as to avoid beam-section limitation upon the beam-section-limiting ability of any aperture of any other disc of said plurality.

Claim 25

Sculpture apparatus for curvature-correcting operation upon the anterior surface of an eye, said apparatus comprising pulsing laser means for producing a succession of tissue-ablating pulses in an output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being such that corneal-tissue ablation per pulse is but a fraction of desired maximum ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so variably controlling zoom-lens setting for each of an indexed plurality of pulses in the course of zoom-lens variation for each of said indexed plurality of mask apertures whereby to achieve a relatively smooth variation of the sectional are of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said mask being one of a plurality of circular discs which are in axially separate array and which are so connected to said control means as to be separately indexible about the same axis of index rotation, each of said discs having a differently characterized progression of varying beam-transmitting sectional area, and one of the apertures of each disc having an opening of such sufficiently large beam-transmitting sectional area as to avoid beam-section limitation upon the beam-section-limiting ability of any aperture of any other disc of said plurality.

Claim 26

Sculpture apparatus for curvature-correcting operation upon the anterior surface of an eye, said apparatus comprising pulsing laser means for producing a succession of tissue-ablating pulses in an output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being such that corneal-tissue ablation per pulse is but a fraction of desired maximum ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so variably controlling zoom-lens setting for each of an indexed plurality of pulses in the course of zoom-lens variation for each of said indexed plurality of mask apertures whereby to achieve a relatively smooth variation of the sectional are of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said mask being one of a plurality of circular discs which are in axially separate array and which are so connected to said control means as to be separately indexible about the same axis of index rotation, each of said discs having a differently characterized progression of varying beam-transmitting sectional area, and one of the apertures of each disc having an opening of such sufficiently large beam-transmitting sectional area as to avoid beam-section limitation upon the beam-section-limiting ability of any aperture of any other disc of said plurality.

Claim 27

Sculpture apparatus according to claim 17 or claim 18, in which the mask apertures of at least one of said disc are circular and of progressively changing radius, whereby to effect a relatively smoothly profiled myopia-correcting diopter change.

Claim 28

Sculpture apparatus according to claim 17 or claim 18, in which the mask apertures of at least one of said discs are elongate rectangular and of progressively changing lateral width, and selectively operable means for orienting the elongation axes of said apertures in accordance with a predetermined orientation of desired astigmatism correction, whereby to effect a relatively smoothly profiled cylindrical diopter change.

Claim 29

Sculpture apparatus according to claim 17 or claim 18, in which the mask apertures of at least one of said discs are circularly annular and of progressively changing inner radius, and in which said mask apertures are of outer radius which when projected to the cornea via said zoom-lens system is greater than that of the maximum curvature-correcting area to be ablated, said controllable means further including continuously variable-iris means for varying said outer radius, said control means so coordinating iris aperture with zoom-lens setting and with the currently indexed mask aperture as to effect a relatively smoothly profiled hyperopia-correcting diopter change within said maximum curvature-correcting area and also to effect a relatively smoothly beveled annular zone of blending slope outwardly from said area of diopter-changing curvature correction.

Claim 30

Sculpture apparatus for curvature-generating operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement of the cornea, the area variation being over a range which at least includes a maximum optically used area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, said controllable means including (a) a zoom-lens system and (b) at least one indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of apertures of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement of the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, the number of mask apertures and the relation of area change between one and the next mask aperture through the progression of area change being selected for limitation of requisite zoom-lens magnification to the range 1:2 of less, for each of the indexed positions of said mask, whereby the variation in energy density at the cornea is within the range 1:4.

Claim 31

Sculpture apparatus for curvature-generating operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement of the cornea, the area variation being over a range which at least includes a maximum optically used area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, said controllable means including (a) a zoom-lens system and (b) at least one indexible mask having a plurality of mask apertures of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of apertures of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement of the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, the number of mask apertures and the relation of area change between one and the next mask aperture through the progression of area change being selected for limitation of requisite zoom-lens magnification to the range 1:2 of less, for each of the indexed positions of said mask, whereby the variation in energy density at the cornea is within the range 1:4.

Claim 32

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting data to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being limited per unit time to ablate but a fraction of a predetermined maximum depth of ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask openings of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of the openings of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said controllable means further including means for varying the intensity of the laser beam, said last-mentioned means being so continuously coordinated with the control of zoom-lens setting as to compensate for flux-density dilution as a function of instantaneous zoom-lens magnification.

Claim 33

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising laser means for producing a tissue-ablating output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting data to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being limited per unit time to ablate but a fraction of a predetermined maximum depth of ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask openings of progressively changing area, and control means connected to said laser means and to said controllable means for so controlling zoom-lens setting for each of an indexed plurality of the openings of said mask as to produce a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said controllable means further including means for varying the intensity of the laser beam, said last-mentioned means being so continuously coordinated with the control of zoom-lens setting as to compensate for flux-density dilution as a function of instantaneous zoom-lens magnification.

Claim 34

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising pulsing laser means for producing a succession of tissue-ablating pulses in an output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being such that corneal-tissue ablation per pulse is but a fraction of desired maximum ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask openings of progressively changing area, and control means connected to said laser means and to said controllable means for so variably controlling zoom-lens setting for each of an indexed plurality of openings of said mask as to deliver a plurality of pulses in the course of zoom-lens variations for each of said indexed plurality of mask openings whereby to achieve a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said controllable means further including means for varying the intensity of the laser beam, said last-mentioned means being so continuously coordinated with the control of zoom-lens setting as to compensate for flux-density dilution as a function of instantaneous zoom-lens magnification.

Claim 35

Sculpture apparatus for curvature-correcting operation upon the anterior surface of the cornea of an eye, said apparatus comprising pulsing laser means for producing a succession of tissue-ablating pulses in an output beam and controllable means for variably limiting the sectional area of said beam at impingement on the cornea, the area variation being over a range which at least includes a maximum curvature-correcting area to be ablated and being symmetrical with respect to a beam-projection axis which coincides with the optical axis of the eye, the intensity of laser-beam projection being such that corneal-tissue ablation per pulse is but a fraction of desired maximum ablation into the stroma region of the cornea, said controllable means including (a) a zoom-lens system and (b) an indexible mask having a plurality of mask openings of progressively changing area, and control means connected to said laser means and to said controllable means for so variably controlling zoom-lens setting for each of an indexed plurality of openings of said mask as to deliver a plurality of pulses in the course of zoom-lens variations for each of said indexed plurality of mask openings whereby to achieve a relatively smooth variation of the sectional area of said beam at impingement on the cornea with an accompanying diopter change at the cornea, said relatively smooth variation being as compared with the stepped variation produced by use of the mask alone, said controllable means further including means for varying the intensity of the laser beam, said last-mentioned means being so continuously coordinated with the control of zoom-lens setting as to compensate for flux-density dilution as a function of instantaneous zoom-lens magnification.

Claim 36

Sculpture apparatus according to claim 23 or claim 24, wherein said last-mentioned means includes a microprocessor having an intensity-control connection to said laser means and a magnification-control connection to said zoom-lens system.

Claim 37

Sculpture apparatus according to claim 23 or claim 24, wherein said last-mentioned means includes variable-density filter means interposed between said laser means and said zoom-lens system.

Claim 38

Sculpture apparatus according to claim 23 or claim 24, wherein said last-mentioned means includes variable-density filter means interposed between said laser means and said zoom-lens system, said variable-density filter means comprising two like variable-density filters in mutually opposite directions of varying density and coupled for opposing displacements through the laser beam in synchronism with variation of zoom-lens setting.

Claim 41

The method of claim 28, in which the annular-spot delivery of the curvature-increasing procedure of step (d) involves varying outer radius which increases radially outwardly of the outer radius of the procedure of step (c).

Claim 42

The method of claim 28, in which the intensity distribution of beam projection to the optically used area exhibits a cross-sectional fall-off in the radially outward direction from said axis, and wherein the exposure time for the procedure of step (d) exceeds that for the procedure of step (c).

Claim 43

The method of claim 28, wherein said substance is epithelium tissue.

Claim 48

The method of claim 32 or claim 33, in which the annular-spot delivery procedure of step (c) involves varying outer radius which increases radially outwardly of the outer radius of the procedure of the circular-spot delivery procedure.

Claim 49

The method of claim 33, in which step (c) involves a further curvature-changing procedure involving varying width of elongate rectangular-spot delivery wherein the elongation extends diametrically through the optical axis and at angular orientation to effect an astigmatism correction.

Claim 52

The method of claim 26, wherein said area is a circle having a radius which is held constant throughout steps (a) and (b).

Claim 53

The method of claim 36, wherein in the course of performing steps (a) and (b) an annular area of the cornea adjacent to and radially outside said optically used area is subjected to tissue-ablating exposure which is annular and of progressively expanding radius.