Device, method, and control program for refractive surgery

Abstract

An apparatus and a method for refractive surgery, in particular LASIK, make provision whereby the apex of the cornea is taken as a basis, as the ablation center, for the refractive procedure. For this purpose, the dependence of the position of the apex on properties of the pupil is determined in the case of the eye to be treated and, from this dependence, measured properties of the pupil are used to calculate the position of the ablation center during the refractive surgery.

The invention claimed is: 
     
       1. Apparatus for refractive surgery comprising the following:
 a laser-beam source; 
 a camera for recording the configured to record an image of an iris and a pupil of the an eye; 
 a computer, comprising storing a control program for controlling the said means to control a laser beam emitted by the laser-beam source according to an ablation profile; wherein, the control program: includes including a function of the relating a position of the an apex of the a cornea of the eye in dependence  depending on at least one instantaneous property of the pupil; 
 the control program, when executed by the computer during the refractive surgery,:  records an instantaneous property of the pupil by means of based on the image recorded by the camera and camera;    determines therefrom, by means of the function, the position of the apex of the cornea based on the instantaneous property of the pupil and the function; and   aligns the ablation profile to one of the thus determined position of the apex or of and a point of the corneal surface having a fixed distance from the apex.   
 
     
     
       2. Apparatus according to  claim 1 , wherein the instantaneous property of the pupil is at least one or more of its dimensions. 
     
     
       3. Apparatus according to  claim 1 , wherein the instantaneous property of the pupil is at least one of its shape and center. 
     
     
       4. Apparatus according to  claim 1 , wherein the control program also determines, by means of a recorded property of the iris, an instantaneous position of at least one of the apex and a predefined point of the cornea having a fixed distance to the apexwherein:
 the function relates the position of the apex of the cornea of the eye to an instantaneous property of the iris; 
 the control program, when executed by the computer during the refractive surgery:
 determines the instantaneous property of the iris based on the image recorded by the camera; and 
 determines the position of the apex of the cornea based on the instantaneous property of the iris and the function. 
 
 
     
     
       5. Apparatus for refractive surgery comprising the following:
 a laser-beam source;   a camera for recording the iris and pupil of the eye;   a computer which executes a control program for the purpose of controlling said means according to an ablation profile, wherein the control program:
 includes a function of the position of the apex of the cornea of the eye in dependence on at least one property of the pupil, 
 during the refractive surgery, records the instantaneous property of the pupil by means of the camera and determines therefrom, by means of said function, the position of the apex of the cornea, and 
 aligns the ablation profile to at least one of the thus determined position of the apex and a point on the corneal surface having a fixed distance from the apex. 
   
     
     
       6. The apparatus of claim  5  1, wherein the at least one property of the pupil upon which the position of the apex is dependent as set forth in the function of the control program includes a relationship of sets forth a dependence of the position of the apex on the instantaneous property of the pupil in a relationship that relates the position of the apex to a pupil width. 
     
     
       7. The apparatus of  claim 6 , wherein the relationship of the position of the apex to the pupil width is determined empirically for the eye to be treated. 
     
     
       8. The apparatus of  claim 7 , wherein empirically determining the dependency of the position of the apex to the pupil width is determined by altering incident visible light on the eye to be treated. 
     
     
       9. The apparatus of  claim 8 , wherein the incident visible light on the eye to be treated is altered in a stepwise manner. 
     
     
       10. The apparatus of claim  5  1, wherein the at least one property of the pupil upon which the position of the apex is dependent as set forth in the function of the control program includes a relationship of sets forth a dependence of the position of the apex on the instantaneous property of the pupil in a relationship that relates the position of the apex to a pupil rotation. 
     
     
       11. The apparatus of  claim 10 , wherein the relationship of the position of the apex to the pupil rotation is determined empirically for the eye to be treated. 
     
     
       12. The apparatus of  claim 11 , wherein empirically determining the dependency of the position of the apex to the pupil rotation is determined by identifying variation of a position of an iris pattern. 
     
     
       13. The apparatus of  claim 1 , wherein the at least one property of the pupil upon which the position of the apex is dependent as set forth in the function of the control program includes a relationship of the position of the apex to a pupil width. 
     
     
       14. The apparatus of  claim 13 , wherein the relationship of the position of the apex to the pupil width is determined empirically for the eye to be treated. 
     
     
       15. The apparatus of  claim 14 , wherein empirically determining the dependency of the position of the apex to the pupil width is determined by altering incident visible light on the eye to be treated. 
     
     
       16. The apparatus of  claim 15 , wherein the incident visible light on the eye to be treated is altered in a stepwise manner. 
     
     
       17. The apparatus of  claim 13 , wherein the at least one property of the pupil upon which the position of the apex is dependent as set forth in the function of the control program includes a relationship of the position of the apex to a pupil rotation. 
     
     
       18. The apparatus of  claim 17 , wherein the relationship of the position of the apex to the pupil rotation is determined empirically for the eye to be treated. 
     
     
       19. The apparatus of  claim 18 , wherein empirically determining the dependency of the position of the apex to the pupil rotation is determined by identifying variation of a position of an iris pattern.