Optical surface identification for laser eye surgery
Systems and methods automatically locate optical surfaces of an eye and automatically generate surface models of the optical surfaces. A method includes OCT scanning of an eye. Returning portions of a sample beam are processed to locate a point on the optical surface and first locations on the optical surface within a first radial distance of the point. A first surface model of the optical surface is generated based on the location of the point and the first locations. Returning portions of the sample beam are processed so as to detect second locations on the optical surface beyond the first radial distance and within a second radial distance from the point. A second surface model of the optical surface is generated based on the location of the point on the optical surface and the first and second locations on the optical surface.
1. A laser eye surgery system, comprising:
a cutting laser subsystem configured to generate a pulsed laser beam;
an optical coherence tomography (OCT) imaging subsystem, the OCT imaging subsystem including an adjustable reference path length, the OCT imaging subsystem configured to produce a detection beam having a plurality of wavelengths such that the detection window spans a range of distances relative to the laser eye surgery system; and
control electronics operably connected to the cutting laser subsystem and the OCT imaging subsystem, the control electronics programmed to:
control the OCT imaging subsystem to locate a centrally-located point on the lens capsule anterior surface;
control the OCT imaging subsystem to direct an OCT sample beam into the eye with the reference path length set to position the detection window to encompass the lens capsule anterior surface and the iris;
process returning portions of the sample beam to identify, relative to the laser eye surgery system, a plurality of edge points within the detection window, each edge point being disposed on an optical surface;
generate a surface model of the lens capsule anterior surface based on the location of the centrally-located point on the lens capsule anterior surface and a subset of the edge points;
select a subset of the edge points that are offset from the surface model of the lens capsule anterior surface; and
generate a surface model of the iris based on the subset of the edge points that are offset from the surface model of the lens capsule anterior surface.
2. The system of claim 1 , wherein the surface model of the iris is an oriented plane.
3. The system of claim 1 , wherein the control electronics is further programmed to:
control the OCT imaging subsystem to generate a surface model of the cornea anterior surface;
generate a curved-line intersection between the iris surface model and the cornea anterior surface model; and
represent the location of the limbus with the curved-line intersection.
4. The system of claim 1 , wherein the control electronics is further programmed to process a video image of the eye to identify the pupil by searching outwardly from a central location to identify edges of the iris.
5. The system of claim 4 , wherein the control electronics is further programmed to generate a curved-line model of the pupil based on the video identified pupil and the iris surface model.