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US 12,728,038 B2Granted
Corneal lenticular incision using a femtosecond laser with improved scanline sweep speed profile
AssigneeAMO Development, LLC
InventorsWenzhi Gao, Hong Fu
Life of this patent
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Abstract
An ophthalmic surgical laser system and method for forming a lenticule in a subject's eye using “fast-scan-slow-sweep” scanning scheme. A high frequency scanner forms a fast scanline, which is placed tangential to a parallel of latitude of the surface of the lenticule and then moved in a slow sweep trajectory along a meridian of longitude of the surface of the lenticule in one sweep. Multiple sweeps are performed along different meridians to form the entire lenticule surface, with the orientation of the scanline rotated between successive sweeps. To reduce acceleration and jerk in the XY stage motion, especially during transition from one sweep to the next, the sweeping speed profile is a sigmoid function.
Claims18
An ophthalmic surgical laser system comprising:
- a laser source configured to generate a pulsed laser beam comprising a plurality of laser pulses;
- a laser delivery system configured to deliver the pulsed laser beam to a target tissue in a subject's eye;
- a high frequency scanner configured to scan the pulsed laser beam back and forth at a predefined frequency;
- an XY-scanner configured to deflect the pulsed laser beam, the XY-scanner being separate from the high frequency scanner;
- a Z-scanner configured to modify a depth of a focus of the pulsed laser beam;
- and
- a controller configured to control the laser source, the high frequency scanner, the XY-scanner and the Z-scanner to successively form a plurality of sweeps which collectively form at least one lenticular incision of a lens in the subject's eye, the lens having a curved surface that defines an apex and a Z axis passing through the apex, wherein each sweep is formed by:
- controlling the laser source to generate the pulsed laser beam;
- controlling the high frequency scanner to deflect the pulsed laser beam to form a scanline, the scanline being a straight line having a predefined length and being tangential to a parallel of latitude of the lens, the parallel of latitude being a circle on the surface of the lens that is perpendicular to the Z axis and has a defined distance to the apex, and
- controlling the XY-scanner and the Z-scanner to move the scanline along a meridian of longitude of the lens, the meridian of longitude being a curve that passes through the apex and has a defined angular position around the Z axis, wherein the scanline is moved at a sweeping speed having a sigmoid profile:
- v
-
- (
- η
- )
- =
- v
- center
- +
- (
- v
- edge
- -
- v
- center
- )
- /
- (
- 1
- +
- e
- -
- slope
- *
- (
- ❘
- "\[LeftBracketingBar]"
- η
- ❘
- "\[RightBracketingBar]"
- η
- max
- -
- inflection
- )
- )
- where v(η) is a magnitude of the sweeping speed, η is a one-dimensional position along the sweep in an XY plane, its absolute value |η| being a radial distance to a lenticule center on the Z axis, ηmax is a maximum radius of the lenticule incision in the XY plane, and vcenter, vedge, slope and inflection are parameters;
- wherein the plurality of sweeps are successively formed one after another along the respective meridians of longitude which are different from one another.
45 more elements
A method for creating a lenticular incision using an ophthalmic surgical laser system, the method comprising the steps of:
- generating, by a laser source, a pulsed laser beam comprising a plurality of laser pulses;
- delivering, by a laser delivery system, the pulsed laser beam to a target tissue in a subject's eye;
- scanning, by a high frequency scanner, the pulsed laser beam back and forth at a predefined frequency;
- deflecting, by an XY-scanner, the pulsed laser beam, the XY-scanner being separate from the high frequency scanner;
- modifying, by a Z-scanner, a depth of a focus of the pulsed laser beam;
- and
- controlling, by a controller, the laser source, the high frequency scanner, the XY-scanner and the Z-scanner to successively form a plurality of sweeps which collectively form at least one lenticular incision of a lens in the subject's eye, the lens having a curved surface that defines an apex and a Z axis passing through the apex, including forming each sweep by:
- controlling the laser source to generate the pulsed laser beam;
- controlling the high frequency scanner to deflect the pulsed laser beam to form a scanline, the scanline being a straight line having a predefined length and being tangential to a parallel of latitude of the lens, the parallel of latitude being a circle on the surface of the lens that is perpendicular to the Z axis and has a defined distance to the apex, and
- controlling the XY-scanner and the Z-scanner to move the scanline along a meridian of longitude of the lens, the meridian of longitude being a curve that passes through the apex and has a defined angular position around the Z axis, wherein the scanline is moved at a sweeping speed having a sigmoid profile:
- v
-
- (
- η
- )
- =
- v
- center
- +
- (
- v
- edge
- -
- v
- center
- )
- /
- (
- 1
- +
- e
- -
- slope
- *
- (
- ❘
- "\[LeftBracketingBar]"
- η
- ❘
- "\[RightBracketingBar]"
- η
- max
- -
- inflection
- )
- )
- where v(η) is a magnitude of the sweeping speed, η is a one-dimensional position along the sweep in an XY plane, its absolute value |η| being a radial distance to a lenticule center on the Z axis, ηmax is a maximum radius of the lenticule incision in the XY plane, and vcenter, vedge, slope and inflection are parameters;
- wherein the plurality of sweeps are successively formed one after another along the respective meridians of longitude which are different from one another.
45 more elements
Dependencies are inferred from the claim text.