Eye tracking device for laser eye surgery using corneal margin detection

Claim 5

The method of claim 1 further comprising: scanning a light spot along a substantially annular trajectory radially outward from the pupil; and measuring signals corresponding to light intensity of reflected light from discrete portions of the annular trajectory to determine a relative position of the eye.

Claim 6

The method of claim 1 wherein the reflected light includes light reflected from the sclera having a first intensity and light reflected from the iris having a second intensity less than the first intensity.

Claim 7

The method of claim 1 wherein the region of the eye is an annular region disposed radially outward from the pupil adjacent to or near the limbus between the sclera and the iris.

Claim 12

The method of claim 7 further comprising positioning the annular trajectory region adjacent to or near the limbus between the sclera and the iris and scanning the light ray around the limbus to determine a reference intensity signal.

Claim 13

The method of claim 8 further comprising tracking subsequent movement of the limbus relative to the annular trajectory by measuring changes in the intensity of the reflected light.

Claim 14

The method of claim 7 wherein the light ray is scanned around the annular trajectory at a reference frequency, the method further comprising: generating an alternating current component of the reference frequency; comparing an amplitude of the light ray signals with an amplitude of the reference frequency to determine a magnitude of eye displacement.

Claim 15

The method of claim 7 wherein the light ray is scanned around the annular trajectory at a reference frequency, the method further comprising: generating an alternating current component of the reference frequency; and comparing a phase of the light ray signals with a phase of the reference frequency signal to determine a vector angle of eye displacement.

Claim 16

The method of claim 7 wherein the light ray is scanned around the annular trajectory by oscillating mirrors positioned between a light source and the eye.

Claim 17

The method of claim 7 further comprising sequentially activating a ring of light sources to sequentially scan light rays around the annular trajectory.

Claim 18

The method of claim 7 further comprising transmitting light through one or more optical fibers to the eye and rotating a distal end portion of the optical fibers to scan the light around the annular trajectory.

Claim 19

The method of claim 7 wherein the light has a wavelength in the infrared region.

Claim 22

The method of claim 16 further comprising: directing an annular light pattern onto the eye radially outward from the pupil; and measuring signals corresponding to light intensity of reflected light from discrete portions of the annular light pattern to determine a relative position of the eye.

Claim 23

The method of claim 16 further comprising: scanning a light spot along a substantially annular trajectory radially outward from the pupil; and measuring signals corresponding to light intensity of reflected light from discrete portions of the annular trajectory to determine a relative position of the eye.

Claim 24

The method of claim 16 wherein the applying energy step comprises projecting ultraviolet radiation onto the cornea to ablate a tissue structure on the optically useful portion of the anterior surface of the cornea.

Claim 25

The method of claim 19 wherein said cornea comprises an epithelium, a Bowman's layer and a stroma, the method further comprising removing the epithelium and at least a portion of the Bowman's layer from the anterior region of the cornea to expose a selected region of the stroma and ablating a portion of the stroma within the selected region.

Claim 26

The method of claim 16 further comprising: before the applying energy step, removing a region of tissue including portions of the limbus to expose an underlying region of the cornea that is substantially non-reflective; scanning a light ray along a substantially annular trajectory, the annular trajectory including at least a portion of the non-reflective underlying portion of the cornea and a reflective portion of the eye that has not been removed; and interpolating a position of the limbus relative to the annular trajectory based on the intensity of the reflected light from said reflective portion of the eye.

Claim 27

An optical system for tracking movement of the eye of a patient comprising: a light source; an optical train for directing a light ray from the light source at a region of the eye including the sclera and the iris; a light detector positioned to receive reflected light from said region of the eye; and a controller coupled to the light detector for measuring an intensity of the reflected light to determine a relative position of the eye.

Claim 28

An optical system for tracking movement of the eye of a patient comprising: a light source; an optical train for directing a light ray from the light source at a region of the eye including the sclera and the iris; a light detector positioned to receive reflected light from said region of the eye; and a controller coupled to the light detector for measuring an intensity of the reflected light to determine a relative position of the eye.

Claim 29

An optical system for tracking movement of the eye of a patient comprising: a light source; an optical train for directing a light ray from the light source at a region of the eye including the sclera and the iris; a light direction system positioned along the optical train, the light direction system being configured to scan the light ray in an annular trajectory around the pupil of the eye; a light detector positioned to receive reflected light from said region of the eye; and a controller coupled to the light detector for measuring an intensity of the reflected light to determine a relative position of the eye, the controller comprising an electrical system coupled to the light detector and configured to measure signals corresponding to light intensity of reflected light from discrete portions of the annular trajectory.

Claim 30

An optical system for tracking movement of the eye of a patient comprising: a light source; an optical train for directing a light ray from the light source at a region of the eye including the sclera and the iris; a light direction system positioned along the optical train, the light direction system being configured to scan the light ray in an annular trajectory around the pupil of the eye; a light detector positioned to receive reflected light from said region of the eye; and a controller coupled to the light detector for measuring an intensity of the reflected light to determine a relative position of the eye, the controller comprising an electrical system coupled to the light detector and configured to measure signals corresponding to light intensity of reflected light from discrete portions of the annular trajectory.

Claim 31

The optical system of claim 23 wherein the light direction system comprises oscillating mirrors positioned between the light source and the eye and a motor for oscillating the mirrors such that the light is scanned around the annular trajectory.

Claim 32

The optical system of claim 23 wherein the light direction system comprises a ring of light sources positioned in an annular array such that sequential activation of the light sources causes light to scan around the annular trajectory.

Claim 33

The optical system of claim 23 wherein the light direction system comprises one or more optical fibers coupled to the light source for transmitting light therethrough, the optical fibers having an end portion for projecting light onto the eye, and a drive for rotating the end portion of the optical fibers to scan the light around the annular trajectory.

Claim 34

The optical system of claim 23 further comprising a calibration system coupled to the light direction system for positioning the annular trajectory substantially coincident with the limbus.

Claim 35

The optical system of claim 23 further comprising a reference synchronization system for scanning a light ray onto a reference light detector at a reference frequency and a reference intensity, and an electrical system for generating an alternating signal having a reference phase and a reference amplitude based on the reference frequency and the reference intensity.

Claim 36

The optical system of claim 28 wherein the electrical system is coupled to the light detector for generating a corneal margin signal having a corneal margin phase and a corneal margin amplitude based on a phase and an amplitude of signals from the reflected light, the electrical system further comprising a phase comparator for comparing the phase of the reflected light signal with the reference phase to determine a vector angle of eye displacement, and an amplitude comparator for comparing the amplitude of the reflected light signal with the reference amplitude to determine a magnitude of eye displacement.

Claim 37

The optical system of claim 22 wherein the light source is configured to direct an annular light pattern onto the eye at or near the limbus, the controller comprising an electrical circuit coupled to the light detector for measuring signals corresponding to light intensity of reflected light from discrete portions of the annular light pattern.

Claim 38

An optical system comprising: a laser assembly for projecting radiation onto a selected region of the anterior surface of the cornea to effect ablation of said selected region to a certain depth; and an eye tracking system for tracking movement of the eye comprising: an optical system including a light source and a light direction system configured to scan a light ray in an annular trajectory around the pupil of the eye; and an electrical system coupled to the optical system and configured to measure signals corresponding to a light intensity of reflected light from discrete portions of the annular trajectory to track a position of the eye.

Claim 39

An optical system comprising: a laser assembly for projecting radiation onto a selected region of the anterior surface of the cornea to effect ablation of said selected region to a certain depth; and an eye tracking system for tracking movement of the eye comprising: an optical system including a light source and a light direction system configured to scan a light ray in an annular trajectory around the pupil of the eye; and an electrical system coupled to the optical system and configured to measure signals corresponding to a light intensity of reflected light from discrete portions of the annular trajectory to track a position of the eye.

Claim 50

The method of claim 36 further comprising: imaging the light beam to a focus at the region so as to more precisely define the region with the beam; rotating the beam around the eye at a reference frequency in a pattern comprising an annular trajectory so as to generate a varying signal at the reference frequency; comparing an amplitude of the varying signal with a reference to determine a magnitude of an eye displacement; comparing a phase angle of the varying signal with the reference so as to determine an angle of the position of the eye; positioning the trajectory to be substantially coincident with the boundary; and adjusting a first radius of the trajectory to match a second radius of the limbus.

Claim 53

The method of claim 38 further comprising: projecting a visible light beam onto the region; imaging the light beam to a focus at the region so as to more precisely define the region with the beam; pulsing the light beam at a known frequency greater than 0.5 kHz; scanning the light beam around the eye in a trajectory to determine a position of the eye, the position being determined from a variation in the intensity of the reflected energy; synchronizing the step of pulsing with the step of scanning; overlapping a position of the light beam at maximum intensity with a previous position of the light beam at maximum intensity during the step of scanning; blanking the visible light beam around a portion of the trajectory over the detected flap; interpolating the measured intensity between measured values of the reflected energy; positioning the trajectory to be substantially coincident with the limbus; rotating the light beam around the eye at a reference frequency in a pattern comprising an annular trajectory so as to generate a varying corneal margin signal at the reference frequency; comparing an amplitude of the varying signal with a reference to determine a magnitude of an eye displacement; comparing a phase angle of the varying signal with the reference so as to determine an angle of the position of the eye; and displacing the trajectory so as to minimize the variation in intensity of the reflected energy, the location of the trajectory corresponding to the position of the eye, and a separation distance between an initial location of the trajectory and the displaced location of the trajectory being greater than a dimension across the measured region.

Claim 54

The method of claim 39 , further comprising: restricting a dimension across the measured region by selectively passing light rays from within the region to a light energy detector and excluding light rays from outside the region from the light energy detector; and deflecting the beam with a beam deflection module, the beam deflection module comprising an optical element selected from the group consisting of lenses, prisms and mirrors.

Claim 57

The method of claim 41 further comprising: projecting a beam of a visible light energy at the eye to form a visible light spot on an uncovered portion of the limbus; scanning the measured region around the eye to determine a position of the eye, the position being determined from a variation in the intensity of the reflected energy; rotating the measured region around the eye at a reference frequency in a pattern comprising an annular trajectory to generate a varying corneal margin signal at the reference frequency; comparing an amplitude of the varying signal with a reference to determine a magnitude of an eye displacement; comparing a phase angle of the varying signal with the reference so as to determine an angle of the position of the eye; positioning the trajectory to be substantially coincident with the limbus; displacing the trajectory so as to minimize the variation in intensity of the reflected energy, the location of the displaced trajectory corresponding to the position of the eye; and separating an initial location of the trajectory from a displaced location of the trajectory by a distance greater than a dimension across the measured region.

Claim 60

The method of claim 43 , further comprising; inputting a laser treatment into a laser system controller; calculating a laser treatment table, the laser treatment table comprising an offset position of the beam from the reference position; loading the laser treatment table in a random access memory of a laser system controller; aligning the eye with the laser treatment area; determining the initial position of the eye, the initial position being the position of the eye being obtained during the step of aligning; storing the initial position of the eye in the random access memory of the laser system controller; determining the current position of the eye; calculating a displacement of the eye from the initial position to the current position; comparing the displacement of the eye to a tolerance; pausing the laser treatment if the displacement of the eye is greater than the tolerance; calculating a new offset position of the eye by adding the offset position of the beam in the table to the displacement of the eye; moving an element of a laser beam deflection module according to the new offset position; pulsing the laser beam; repeating steps of determining the current position of the eye through pulsing the laser beam; and ending the laser treatment.

Claim 61

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a light source for making a light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optically non-transmitting material with an aperture formed in the material for restricting a dimension across the measured region by selectively passing the light energy from the region through the aperture to the detector, the material blocking light rays from outside the measured region; an optical train for scanning the region around the eye in a trajectory; a controller coupled to the light detector for measuring the reflected light energy to determine a relative position of the eye.

Claim 62

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a light source for making a light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optically non-transmitting material with an aperture formed in the material for restricting a dimension across the measured region by selectively passing the light energy from the region through the aperture to the detector, the material blocking light rays from outside the measured region; an optical train for scanning the region around the eye in a trajectory; a controller coupled to the light detector for measuring the reflected light energy to determine a relative position of the eye.

Claim 63

The eye tracker of claim 45 , further comprising: an imaging lens for imaging the region onto the aperture.

Claim 64

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a visible light source for making a light energy; an imaging lens for projecting the light energy onto the eye as a visible light spot; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optically non-transmitting material with an aperture formed in the material for restricting a dimension across the measured region by selectively passing the light energy from the region through the aperture to the detector, the material blocking light rays from outside the measured region; an optical train for scanning the region around the eye in a trajectory; a controller coupled to the light detector for measuring the reflected light energy to determine a relative position of the eye.

Claim 65

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a visible light source for making a light energy; an imaging lens for projecting the light energy onto the eye as a visible light spot; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optically non-transmitting material with an aperture formed in the material for restricting a dimension across the measured region by selectively passing the light energy from the region through the aperture to the detector, the material blocking light rays from outside the measured region; an optical train for scanning the region around the eye in a trajectory; a controller coupled to the light detector for measuring the reflected light energy to determine a relative position of the eye.

Claim 66

The eye tracker of claim 47 , further comprising: a light beam deflection module for scanning the light spot and the measured region around the eye in an annular trajectory; a reflecting surface for aligning the projected light spot with the measured region so as to be confocal on the eye.

Claim 67

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a display screen comprising a light spot comprising a visible light energy; an imaging lens for projecting the light energy onto the eye as a visible light spot; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; and a controller coupled to the light detector for measuring the reflected light energy to determine a relative position of the eye.

Claim 68

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a display screen comprising a light spot comprising a visible light energy; an imaging lens for projecting the light energy onto the eye as a visible light spot; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; and a controller coupled to the light detector for measuring the reflected light energy to determine a relative position of the eye.

Claim 69

The eye tracker of claim 49 , further comprising: a tunable bandpass filter for filtering a corneal margin signal; a peak hold detector for holding a signal peak; a phase comparator coupled to a reference signal for determining a phase angle of the signal peak; and a divider for dividing the signal peak by a reference.

Claim 70

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a light source for making a light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optical train for scanning the region over the eye; and a controller coupled to the light detector for automatically detecting a tissue covering the boundary, and measuring the reflected light energy from an uncovered portion of the boundary to determine a relative position of the eye.

Claim 71

An eye tracker for measuring a position of an eye, the eye having a boundary, the tracker comprising: a light source for making a light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optical train for scanning the region over the eye; and a controller coupled to the light detector for automatically detecting a tissue covering the boundary, and measuring the reflected light energy from an uncovered portion of the boundary to determine a relative position of the eye.

Claim 72

The eye tracker of claim 51 , further comprising: an imaging lens for projecting the light energy onto the eye as a visible light spot, the light energy comprising a visible light energy; an optically non-transmitting material with an aperture formed in the material for restricting a dimension across the measured region by selectively passing the light energy from the region through the aperture to the detector, the material blocking light rays from outside the measured region; a light beam deflection module for scanning the light spot and the measured region around the eye in an annular trajectory; a reflecting surface for aligning the projected light spot with the measured region so as to be confocal on the eye; a blanking circuit for blanking the projected visible light spot over the detected tissue covering the boundary, the boundary comprising a portion of the limbus; an automatic flap detection circuit for detecting a flap of incised tissue; an interpolation circuit for interpolating the measured light energy; and an offset circuit for displacing the annular trajectory to match the position of the eye.

Claim 73

The eye tracker of claim 51 wherein the light source comprises a display screen.

Claim 74

The eye tracker of claim 53 , further comprising: an imaging lens for projecting the light energy onto the eye as a visible light spot, the light energy comprising a visible light energy; a blanking circuit for blanking the projected visible light spot over the detected tissue covering the boundary, the boundary comprising a portion of the limbus; an interpolation circuit for interpolating the measured light energy; and an offset circuit for displacing the annular trajectory to match the position of the eye.

Claim 75

A laser surgery system integrated with an eye tracker, the system comprising: a laser for generating a beam of an ablative laser energy; a movable laser beam path that is variably offset from a reference position; a movable eye tracker axis, the eye tracker axis being movable so as to match a position of the eye, the eye tracker axis further being independently movable relative to the laser beam path; a laser system controller for offsetting the laser beam path according to a position of the eye tracker axis and value of a laser treatment table.

Claim 76

A laser surgery system integrated with an eye tracker, the system comprising: a laser for generating a beam of an ablative laser energy; a movable laser beam path that is variably offset from a reference position; a movable eye tracker axis, the eye tracker axis being movable so as to match a position of the eye, the eye tracker axis further being independently movable relative to the laser beam path; a laser system controller for offsetting the laser beam path according to a position of the eye tracker axis and value of a laser treatment table.

Claim 77

The laser surgery system of claim 55 , further comprising: a light source for making a visible light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; an optical train for scanning the region over the eye; an eye tracker controller coupled to the light detector for automatically detecting a tissue covering the boundary, and measuring the reflected light energy from an uncovered portion of the boundary to determine a relative position of the eye; an imaging lens for projecting the light energy onto the eye as a visible light spot, the light energy comprising a visible light energy; a blanking circuit for blanking the projected visible light spot over the detected tissue covering the boundary, the boundary comprising a portion of the limbus; an interpolation circuit for interpolating the measured light energy; and an offset circuit for displacing the annular trajectory to match the position of the eye.

Claim 78

An integrated eye tracker and laser surgery system for laser sculpting a cornea of an eye to a predetermined shape, the eye having a boundary, the system comprising: a laser for generating a beam of an ablative laser energy; a light source for making a visible light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; a laser beam deflection module for offsetting a path of the beam and an axis of the eye tracker; an eye tracker controller coupled to the light detector for automatically detecting a tissue covering the boundary, and measuring the reflected light energy from an uncovered portion of the boundary to determine a relative position of the eye; and a laser system controller for offsetting the laser beam path according to a position of the eye tracker axis and a value of a laser treatment table.

Claim 79

An integrated eye tracker and laser surgery system for laser sculpting a cornea of an eye to a predetermined shape, the eye having a boundary, the system comprising: a laser for generating a beam of an ablative laser energy; a light source for making a visible light energy; a light detector positioned to receive the light energy reflected from a region of the eye, the region including a portion of the boundary; a laser beam deflection module for offsetting a path of the beam and an axis of the eye tracker; an eye tracker controller coupled to the light detector for automatically detecting a tissue covering the boundary, and measuring the reflected light energy from an uncovered portion of the boundary to determine a relative position of the eye; and a laser system controller for offsetting the laser beam path according to a position of the eye tracker axis and a value of a laser treatment table.

Claim 80

The laser surgery system of claim 57 , further comprising: an imaging lens for projecting the light energy onto the eye as a visible light spot; a blanking circuit for blanking the projected visible light spot over the detected tissue covering the boundary, the boundary comprising a portion of a limbus of the eye; an interpolation circuit for interpolating the measured light energy; and an offset circuit for displacing the measured region to match the position of the eye.