High speed corneal lenticular incision using a femtosecond laser

A method for creating a lenticular incision using an ophthalmic surgical laser system, the method comprising the steps of:

• generating a pulsed laser beam;
• delivering the pulsed laser beam to a target 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 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 high frequency scanner to deflect the pulsed laser beam to form a scan line, the scan line 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 scan line 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 a sweeping speed of moving the scan line along the meridian of longitude varies with a position of the scan line along the meridian of longitude, wherein the sweeping speed is higher when the scan line passes through the apex than when the scan line is at an edge of the lenticular incision,
• wherein the plurality of sweeps are successively formed one after another along the respective meridians of longitude which are different from one another.

An ophthalmic surgical laser system comprising:

• a laser delivery system for delivering a pulsed laser beam to a target in a subject's eye;
• a high frequency scanner to scan the pulsed laser beam back and forth at a predefined frequency;
• an XY-scanner to deflect the pulsed laser beam, the XY-scanner being separate from the high frequency scanner;
• a Z-scanner to modify a depth of a focus of the pulsed laser beam;
• and
• a controller configured to control 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 high frequency scanner to deflect the pulsed laser beam to form a scan line, the scan line 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,
• controlling the XY-scanner and the Z-scanner to move the scan line 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, and
• controlling the laser delivery system to vary a laser pulse energy during each sweep to use a lower laser pulse energy when the scan line is located within a vicinity of the apex of the lenticule than when the scan line is located at an edge of the lenticule,
• wherein the plurality of sweeps are successively formed one after another along the respective meridians of longitude which are different from one another.