US5423801A — Laser corneal surgery

Claim 1

Independent Claim 176 words

A method of reprofiling a cornea to correct a refractive error in an eye, the method comprising aligning a laser means for delivering a pulsed beam of laser radiation to the cornea, with an optical axis of a cornea, the cornea having an epithelial surface, an underlying stroma and a Bowman's membrane disposed between the epithelial surface and the stroma; selectively ablating and reshaping the cornea with an erodable means for masking said radiation, the masking means being disposed between the laser means and the surface, wherein the masking means has a selected composition and thickness, is erodable by radiation from the laser means and has a pre-defined profile of resistance to erosion by laser radiation such that upon irradiation a portion of the radiation is selectively absorbed by the masking means and another portion is transmitted to the surface of the cornea in accordance with the profile of the masking means to selectively erode the surface; and controlling the laser radiation so that ablation terminates substantially within the Bowman's membrane and not the underlying stroma.

Claim 2

Independent Claim 176 words

A method of reprofiling a cornea to correct a refractive error in an eye, the method comprising aligning a laser means for delivering a pulsed beam of laser radiation to the cornea, with an optical axis of a cornea, the cornea having an epithelial surface, an underlying stroma and a Bowman's membrane disposed between the epithelial surface and the stroma; selectively ablating and reshaping the cornea with an erodable means for masking said radiation, the masking means being disposed between the laser means and the surface, wherein the masking means has a selected composition and thickness, is erodable by radiation from the laser means and has a pre-defined profile of resistance to erosion by laser radiation such that upon irradiation a portion of the radiation is selectively absorbed by the masking means and another portion is transmitted to the surface of the cornea in accordance with the profile of the masking means to selectively erode the surface; and controlling the laser radiation so that ablation terminates substantially within the Bowman's membrane and not the underlying stroma.

Claim 3

Dependent Claim 24 words

The method of claim 1 wherein the method further includes varying the thickness of the masking means to provide the pre-defined profile of resistance.

Claim 4

Dependent Claim 24 words

The method of claim 1 wherein the method further comprises varying the composition of the masking means to provide the pre-defined profile of resistance.

Claim 5

Dependent Claim 45 words

The method of claim 1 further comprising the step of disposing a beam shaping means between the laser means and the cornea for varying a size of the beam of laser radiation incident upon the masking means and thereby selectively ablating and reshaping the cornea.

Claim 6

Dependent Claim 109 words

The method of claim 4 further includes the step of employing an optical system for receiving and transmitting at least a portion of the beam of laser radiation provided by the laser means, the optical system providing at least one region of divergence or convergence of the beam, and further including a beam-shaping stop means movable axially along the beam in the region of convergence or divergence, said stop means having at least one beam-shaping window and one beam-shaping stop portion, whereby the proportion of the total beam cross-section which passes through said window varies with the movement of the stop means axially along the beam in that region.

Claim 7

Dependent Claim 34 words

A method according to claim 4 in which the size of the area exposed to and eroded by the pulses of laser radiation is varied in a controlled manner by varying the beam size.

Claim 8

Dependent Claim 49 words

The method of claim 1 wherein the method of reprofiling further comprises measuring a parameter which is a function of a shape of the cornea; comparing such measurement with a desired value; and deriving a feedback control signal from such comparison to provide further control for the laser means.

Claim 9

Dependent Claim 20 words

The method of claim 7 wherein the step of measuring a parameter comprises measuring a curvature of the corneal surface.

Claim 10

Independent Claim 194 words

A system for reprofiling a corneal surface, the system comprising laser means for delivering a pulsed beam of laser radiation to the cornea, said laser means being adapted for alignment with an optical axis of a cornea, the cornea having an epithelial surface, an underlying stroma and a Bowman's membrane disposed between the epithelial surface and the stroma; beam-shaping means disposable between the laser means and the cornea for selectively ablating and reshaping the cornea wherein the beam-shaping means further includes an erodable means for masking said radiation, the masking means being disposed between the laser means and the corneal surface, wherein the masking means has a selected composition and thickness, is erodable by radiation from the laser means and has a pre-defined profile of resistance to erosion by laser radiation such that upon irradiation a portion of the radiation is selectively absorbed by the masking means and another portion is transmitted to the surface of the cornea in accordance with the profile of the masking means to selectively erode the surface; and control means for controlling the laser radiation so that ablation terminates substantially within the Bowman's membrane and not the underlying stroma.

Claim 11

Independent Claim 194 words

A system for reprofiling a corneal surface, the system comprising laser means for delivering a pulsed beam of laser radiation to the cornea, said laser means being adapted for alignment with an optical axis of a cornea, the cornea having an epithelial surface, an underlying stroma and a Bowman's membrane disposed between the epithelial surface and the stroma; beam-shaping means disposable between the laser means and the cornea for selectively ablating and reshaping the cornea wherein the beam-shaping means further includes an erodable means for masking said radiation, the masking means being disposed between the laser means and the corneal surface, wherein the masking means has a selected composition and thickness, is erodable by radiation from the laser means and has a pre-defined profile of resistance to erosion by laser radiation such that upon irradiation a portion of the radiation is selectively absorbed by the masking means and another portion is transmitted to the surface of the cornea in accordance with the profile of the masking means to selectively erode the surface; and control means for controlling the laser radiation so that ablation terminates substantially within the Bowman's membrane and not the underlying stroma.

Claim 12

Dependent Claim 25 words

The system of claim 9 wherein the masking means further comprises a masking means of a selected thickness to provide the pre-defined profile of resistance.

Claim 13

Dependent Claim 25 words

The system of claim 9 wherein the masking means further comprises a masking means of a selected composition to provide the pre-defined profile of resistance.

Claim 14

Dependent Claim 56 words

The system of claim 9 wherein the system further comprises measuring means for measuring a parameter which is a function of a shape of the cornea; comparison means for comparing such measurement with a desired value; and feedback means for deriving a feedback control signal from such comparison to provide further control for the laser means.

Claim 15

Dependent Claim 19 words

The system of claim 12 wherein the measuring means comprises means for measuring a curvature of the corneal surface.

Claim 16

Dependent Claim 42 words

The system of claim 9 wherein the beam shaping means further comprises am optical system for stopping a portion of the beam of laser radiation between the laser means and the cornea to vary the beam size and thereby provide selective ablation.

Claim 17

Dependent Claim 85 words

The system of claim 14 further includes means for providing at least one region of divergence or convergence of the beam of laser radiation, and further includes a beam-shaping stop means movable axially along the beam in the region of convergence or divergence, said stop means having at least one beam-shaping window and one beam-shaping stop portion, whereby the proportion of the total beam cross-section which passes through said window varies with the movement of the stop means axially along the beam in that region.

Claim 18

Dependent Claim 39 words

A system according to claim 14 in which the beam-shaping means further includes means for varying an area exposed to and eroded by the pulses of laser radiation in a controlled manner by varying a size of the beam.

Claim 19

Dependent Claim 195 words

A continuous procedure for laser reprofiling a cornea to correct a refractive error in the eye, said procedure comprising: aligning a laser means for delivering a pulsed beam of laser radiation to the cornea in position relative to a cornea, the cornea having an epithelial surface, an underlying stroma and a Bowman's membrane disposed between the epithelial surface and the stroma; ablating an area of the cornea by delivering pulses of laser radiation to the cornea, such that portions of said epithelial surface and Bowman's membrane are ablated concurrently by cumulative exposure to the laser radiation using an erodable mask disposed between said laser means and said epithelial layer, wherein said mask has a selected composition and thickness, is erodable by radiation from the laser means and has a predetermined profile of resistance to erosion by laser radiation such that upon irradiation, said mask erodes in a manner such as to achieve said ablation profile in said Bowman's membrane; varying the area of the cornea to which pulses are delivered to selectively ablate and reshape the cornea; and controlling the laser radiation so that ablation terminates substantially within Bowman's membrane and not the underlying stroma.

Claim 20

Dependent Claim 195 words

A continuous procedure for laser reprofiling a cornea to correct a refractive error in the eye, said procedure comprising: aligning a laser means for delivering a pulsed beam of laser radiation to the cornea in position relative to a cornea, the cornea having an epithelial surface, an underlying stroma and a Bowman's membrane disposed between the epithelial surface and the stroma; ablating an area of the cornea by delivering pulses of laser radiation to the cornea, such that portions of said epithelial surface and Bowman's membrane are ablated concurrently by cumulative exposure to the laser radiation using an erodable mask disposed between said laser means and said epithelial layer, wherein said mask has a selected composition and thickness, is erodable by radiation from the laser means and has a predetermined profile of resistance to erosion by laser radiation such that upon irradiation, said mask erodes in a manner such as to achieve said ablation profile in said Bowman's membrane; varying the area of the cornea to which pulses are delivered to selectively ablate and reshape the cornea; and controlling the laser radiation so that ablation terminates substantially within Bowman's membrane and not the underlying stroma.

Claim 21

Dependent Claim 27 words

The continuous procedure of claim 17 wherein the step of ablating the cornea further comprises ablating the cornea without pretreatment of the cornea to remove epithelial tissue.

Claim 22

Dependent Claim 24 words

The continuous procedure of claim 17 wherein said profile of resistance of said mask is obtained by selecting a mask having a non-uniform thickness.

Claim 23

Dependent Claim 24 words

The continuous procedure of claim 17 wherein said profile of resistance of said mask is obtained by selecting a mask having a non-uniform composition.

Claim 24

Dependent Claim 83 words

The continuous procedure of claim 20 further comprising the step of feedback testing of said eye to determine if said ablation profile is achieved, said feedback testing having the substeps of: measuring a parameter which is related to said ablation profile, comparing the measurement of the parameter with a predetermined value, determining the extent of achievement of said profile from said measurement comparison, and providing a feedback signal to said laser means to control said pulses of laser radiation to achieve said profile.

Claim 25

Dependent Claim 21 words

The continuous procedure of claim 21 wherein substep of measuring said parameter further comprises measuring a curvature of said Bowman's membrane.

Claim 26

Dependent Claim 38 words

The continuous procedure of claim 17 wherein said ablation profile in said Bowman's membrane is achieved by the step of varying a shape of the beam of laser radiation incident on said epithelial layer and said Bowman's membrane.

Claim 27

Dependent Claim 59 words

The continuous procedure of claim 23 wherein said step of varying the shape of the irradiating laser beam comprises having said beam traverse an optical system which reshapes said beam by providing at least one region of divergence or convergence of said beam, and further induces a beam shaping stop movable axially along said beam to shape said beam.

Claim 28

Dependent Claim 20 words

The continuous procedure of claim 23 wherein said change in shape of said beam comprises a change in beam area.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1998-06-12	1998-12-12	1999-06-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2002-06-12	2002-12-12	2003-06-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2006-06-12	2006-12-12	2007-06-13	$7700.00	Window Closed / Lapsed

Laser corneal surgery

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