Method and system for laser treatment of refractive errors using offset imaging

The method of performing selective ablation of a corneal surface of an eye to effect a desired corneal shape, said method comprising the steps of:

• (a) directing a laser beam along a path;
• (b) profiling the beam with a variable width slit to produce a profiled beam;
• (c) establishing a center of rotation for the profiled beam;
• (d) displacing said profiled beam from the center of rotation by a displacement and varying the displacement of said profiled beam from the center of rotation and
• (e) varying an angular position of said profiled beam about the center of rotation to cause said beam to describe a path referenced to the center of rotation.

A method of performing selective ablation of a corneal surface of an eye to effect a predetermined hyperopic refractive correction, said method comprising the steps of:

• (a) directing a laser beam along a path;
• and
• (b) selectively irradiating the corneal surface of the eye to produce said hyperopic refractive correction by:
• (i) intercepting the beam with a variable width slit to produce a profiled beam having an initial width;
• (ii) establishing a center of rotation for the profiled beam;
• (iii) displacing the profiled beam exiting the slit by an initial amount from the center of rotation;
• (iv) rotating the slit and profiled beam by a predetermined angular amount with reference to the center of rotation;
• (v) adjusting the slit width;
• (vi) displacing the profiled beam exiting the slit by a selected amount;
• and
• (vii)repeating steps (iv)-(vi) until the desired hyperopic correction is completed.

A method of performing selective ablation of a corneal surface of an eye to effect a desired corneal shape, said method comprising the steps of:

• (a) directing a laser beam toward a variable aperture;
• (b) profiling the beam with the variable aperture to produce a variable area profiled beam, wherein said step (b) of profiling includes the step of intercepting the laser beam with a variable width slit and a variable diameter diaphragm;
• and
• (c) scanning the profiled beam over a predetermined area of a corneal surface while varying the aperture to change the profiled beam in a predetermined manner, said step (c) of scanning including the steps of establishing an axis of rotation for the profiled beam, and:
• (i) selectably laterally deflecting the beam path from the axis by a displacement amount,
• (ii) varying an angular position of the profiled beam about the axis of rotation, and
• (iii) varying the displacement amount from the axis in a predetermined manner.

A method of performing selective ablation of a corneal surface of an eye to effect a desired corneal resculpting, said method comprising the steps of:

• directing a laser beam toward the cornea along a beam path;
• establishing a center of rotation for the beam;
• displacing said beam path from the center of rotation by a displacement, wherein the beam has an elongate substantially rectangular beam shape, and wherein the displacing step is performed so that the elongate substantially rectangular beam shape is oriented laterally relative to the center of rotation;
• varying the displacement of said beam from the center of rotation;
• varying an angular position of said beam about the center of rotation and rotating the elongate substantially rectangular beam shape so that the rotated elongate substantially rectangular beam shape is laterally oriented relative to the center of rotation;
• intercepting the beam with a variable diameter iris and a variable width slit, and varying a diameter of the iris and a width of the slit;
• and
• rotating the variable width slit in coordination with the varying of the angular position of the beam, the slit having a first edge movable relative to an opposed second edge, wherein the slit rotating step is performed so that a first elongate side of the beam defined by the first edge of the slit comprises an inner edge oriented toward the axis of rotation and a second elongate side of the beam defined by the second edge of the slit comprises an outer edge oriented toward a peripheral boundary of said desired corneal resculpting.