Surface erosion using lasers

A method of eroding a surface by laser energy, said method comprising the steps of:

• aligning a surface with a laser means, which is operable to deliver a beam of photoablative pulses of laser energy along a path to the surface;
• adjusting the size of the area on the surface to which the pulses are delivered;
• and
• operating a beam dimension control means disposed along said path for optically controlling said beam to deliver pulses of laser energy of variable cross-sectional area to the surface while maintaining a substantially constant energy per unit area during each pulse.

A laser system for eroding and thereby shaping or reprofiling a surface, said laser system comprising:

• support means for aligning a surface to be eroded relative to an optical axis (or vice versa),
• a beam delivery system for relaying energy from a laser light source onto the surface along said optical axis,
• a laser light source, power supply and an associated control circuit for generating pulses of laser energy for application to the surface;
• and
• beam dimension control means disposed along said optical axis, including optical means for optically controlling the area over which the pulses of laser energy are applied to the surface while maintaining a substantially constant energy per unit area during each pulse, thereby causing greater or lesser ablation of selected regions of the surface.

A method of eroding an area of a cornea of an eye said method comprising the steps of:

• fixing an eye relative to laser means operable to deliver a beam of photoablative pulses of laser energy along a path to the surface of the cornea;
• varying the area on the surface of the cornea to which the pulses are delivered in a controlled manner;
• and
• operating a beam dimension control means disposed along said path for optically controlling said beam to deliver pulses of laser to the varied areas of the surface while maintaining a substantially constant energy per unit area during each pulse.

A method of removing corneal ulcers comprising steps of:

• fixing an eye relative to laser means operable to deliver a beam of photoablative pulses of laser energy along a path to the surface of the cornea;
• varying the area on the surface of the cornea to which the pulses are delivered in a controlled manner so as to expose the corneal ulcer;
• and
• operating a beam dimension control means disposed along said path for optically controlling said beam to deliver pulses of laser energy of variable cross-sectional area to the ulcer while maintaining a substantially constant energy per unit area during each pulse.

A method of preparing a bed for a corneal transplant in which corneal material is removed by erosion using a method comprising the steps of:

• fixing an eye relative to the laser means to deliver a beam of photoablative pulses of laser energy along a path to the surface of the cornea;
• varying the area on the surface of the cornea to which the pulses are delivered in a controlled manner so as to expose a corneal transplant bed;
• and
• operating a beam dimension control means disposed along said path for optically controlling said beam to deliver pulses of laser energy of variable cross-sectional area to the transplant bed while maintaining a substantially constant energy per unit area during each pulse.

A method of preparing a donor implant for a corneal transplant in which the implant is obtained from a donor cornea by eroding the surrounding area of the donor cornea by a method comprising the steps of:

• fixing an eye relative to laser means to deliver a beam of photoablative pulses of laser energy along a path to the surface of the cornea;
• varying the area on the surface of the cornea to which the pulses are delivered in a controlled manner so as to expose a region surrounding a donor cornea;
• and
• operating a beam dimension control means disposed along said path for optically controlling said beam to deliver pulses of laser energy of variable cross-sectional area to the surrounding region while maintaining a substantially constant energy per unit area during each pulse.

A corneal reprofiling system for modifying the surface of a cornea of an eye, the system comprising:

• a laser means generating a beam of pulses of laser light along a path at an energy level, such that the light pulses can be absorbed in a thin surface layer of a cornea of an eye to induce photoablation:
• a support means for aligning an eye relative to the laser means;
• and
• a beam dimension control means disposed along the path, including a beam-forming optical means for optically varying a area over which the laser light is incident while maintaining a substantially constant energy per unit area during each pulse.