Corneal topography measurement and alignment of corneal surgical procedures
Methods and apparatus are configures to measure an eye without contacting the eye with a patient interface, and these measurements are used to determine alignment and placement of the incisions when the patient interface contacts the eye. The pre-contact locations of one or more structures of the eye can be used to determine corresponding post-contact locations of the one or more optical structures of the eye when the patient interface has contacted the eye, such that the laser incisions are placed at locations that promote normal vision of the eye. The incisions are positioned in relation to the pre-contact optical structures of the eye, such as an astigmatic treatment axis, nodal points of the eye, and visual axis of the eye.
1 . A method of treating an eye, comprising placing an intraocular lens near a nodal point of the eye, the nodal point being one of two points of the eye wherein an incoming ray aimed at one of the two points is refracted by the eye into a refracted ray which appears to have come from another one of the two points and which forms a same angle with respect to an optical axis as the incoming ray does.
2 . The method of claim 1 , wherein the nodal point is an anterior node of the eye.
3 . The method of claim 2 , wherein the step of placing the intraocular lens includes aligning the intraocular lens along a visual axis of the eye that extends from the anterior node of the eye.
4 . The method of claim 2 , wherein the step of placing the intraocular lens includes aligning an optical node of the intraocular lens, which corresponds to a center of the intraocular lens, with the anterior node of the eye.
5 . The method of claim 2 , further comprising, prior to the step of placing the intraocular lens, forming a capsulorhexis in an anterior lens capsule of the eye, the capsulorhexis being centered on a visual axis of the eye that extends from the anterior node.
6 . The method of claim 5 , further comprising incising a structure in the anterior lens capsule, the incised structure being sized to receive a protruding structure of the intraocular lens to hold the intraocular lens in place.
7 . A method of treating an eye, comprising:
using a measurement apparatus to measure a first topography and/or a first tomography of the eye without a patient interface contacting the eye;
capturing a first image of an iris of the eye without the patient interface contacting the eye;
placing a patient interface of a surgical laser system in contact with the eye;
using the surgical laser system to measure a second topography and/or a second tomography of the eye with the patient interface contacting the eye;
capturing a second image of the iris of the eye with the patient interface contacting the eye;
based on the first and second images, and based on the first topography and/or the first tomography and the second topography and/or the second tomography, identifying an anterior node and a visual axis of the eye with the patient interface contacting the eye;
forming a capsulorhexis in an anterior lens capsule of the eye, the capsulorhexis being centered on the visual axis of the eye that extends from the anterior node; and
placing an intraocular lens near the anterior node of the eye.