Ocular modeling methods and apparatus

Abstract

A method and apparatus for modelling a lens ( 104 ) of an eye ( 100 ), comprising: measuring ( 302 ) the anterior shape of the eye's cornea ( 102 ); determining ( 304 ) direct optical measurements of at least one parameter of the cornea ( 102 ) of the eye ( 100 ) and at least one parameter of the lens ( 104 ) of the eye ( 100 ); determining ( 306 ) the refractive index of the cornea; correcting ( 308 ) the optical measurements to account for the effect of the refractive index of the cornea on the direct optical measurements; measuring ( 310 ) the aberration of the eye; calculating ( 312 ) the refractive index of the lens by combining the corrected measurements and the aberration; and further correcting ( 314 ) the optical measurements of the lens to account the effect of the refractive index of the lens on the direct optical measurements.

1 .- 41 . (canceled) 
     
     
         42 . A method of modeling a lens of an eye having a cornea, the method comprising:
 performing a first type of direct optical measurement of a first parameter of the cornea and performing a second type of direct optical measurement of a second parameter of the cornea;   performing the first type of direct optical measurement of a first parameter of the lens and performing the second type of direct optical measurement of a second parameter of the lens;   determining from the first and second parameters of the cornea and the first and second parameters of the lens a third parameter of the cornea;   correcting the first and second types of direct optical measurements of the first and second parameters of the cornea and the first and second parameters of the lens to form corrected measurements of the first and second parameters of the cornea and the first and second parameters of the lens by accounting for an effect of the third parameter of the cornea on the first and second type of direct optical measurements of the first and second parameters of the cornea and the first and second parameters of the lens;   calculating a third parameter of the lens by combining the corrected first and second types of direct optical measurements of the first and second parameters of the cornea and first and second parameters of the lens; and   correcting the first and second types of direct optical measurements of the first and second parameters of the cornea and the first and second parameters of the lens to account for the effect of the third parameter of the lens on the direct optical measurements of the first and second parameters of the cornea and the first and second parameters of the lens.   
     
     
         43 . The method of  claim 42  wherein the first type of direct optical measurement and the second type of direct optical measurement are selected from the group consisting of: topography, refractometry, and interferometery. 
     
     
         44 . The method of  claim 42  wherein the first and second parameters of the cornea is selected from the group consisting of: cornea thickness, a posterior cornea shape and a distance from a back of the cornea to a front of the lens; 
     
     
         45 . The method of  claim 42  wherein the first and second parameters of the lens is selected from the group consisting of: an anterior lens shape, a posterior lens shape, a lens thickness and a distance from a back of lens to a retina of the eye. 
     
     
         46 . The method of  claim 42  wherein a refractive index of the cornea is determined by a refractometer. 
     
     
         47 . The method of  claim 42  wherein a refractive index of the cornea is determined by combining the first and second direct optical measurements of the first and second parameters of the cornea of the eye. 
     
     
         48 . The method of  claim 42  wherein the first and second types of direct optical measurements measure at least one of:
 a total ocular refraction and aberration in the absence of the lens; 
 a total volume of aqueous; 
 a total refraction and aberration with fluid in a lens capsule and an anterior chamber of the eye; or and 
 a distance from the back of the cornea to the retina as measured in the absence of the lens. 
 
     
     
         49 . The method of  claim 42 , wherein at least one of a refractive index of the cornea, a refractive index of the lens, an anterior and a posterior shape of the cornea, and an anterior and a posterior shape of the lens is measured using a laser array source comprising one or more lasers. 
     
     
         50 . The method of  claim 49  wherein measuring the anterior or posterior shape of the cornea comprises:
 capturing one or more images of a pattern of laser spots generated on the anterior surface or the posterior surface of the cornea by the laser array source; 
 forming an averaged image from the captured images; and 
 comparing the averaged image to a spacing and an arrangement of the lasers of the laser array source. 
 
     
     
         51 . The method of  claim 49 , wherein measuring the anterior or posterior lens shape comprises:
 capturing one or more images of a pattern of laser spots generated on the anterior or posterior surface of the lens by the laser array source;   forming an averaged image from the captured images; and   comparing the averaged image to a spacing and an arrangement of the lasers of the laser array source.   
     
     
         52 . The method of  claim 51 , further comprising:
 forming laser spots on both the anterior and posterior lens surfaces, and wherein the refractive index of the lens is determined using a difference image determined using the laser spot appearing on the anterior of the lens and the laser spot appearing on the posterior of the lens.   
     
     
         53 . A method of determining an optimum position for a replacement intraocular lens based on an effective position of a natural lens having an anterior surface and a posterior surface, the method comprising:
 modeling the natural lens using the method of claim  1  to determine the anterior and posterior surfaces of the natural lens;   extrapolating the anterior and posterior surfaces to cross points; and   determining the optimum position defined by a line joining said cross points.   
     
     
         54 . A method of determining an optimum position for a replacement intraocular lens based on an effective position of the natural lens having an anterior surface and a posterior surface, the method comprising:
 modeling the natural lens using the method of claim  1  to determine the anterior and posterior surfaces of the natural lens;   determining a diameter of the natural lens;   extrapolating the anterior and posterior lens surfaces to the diameter;   determining an arc length of the natural lens using the diameter; and   determining the optimum position to lie at the midpoint of the arc length.   
     
     
         55 . A method of determining an optimum position for a replacement intraocular lens based on an effective position of a natural lens having an anterior surface and a posterior surface, the method comprising:
 modeling the natural lens using the method of claim  1  to determine the anterior and posterior surfaces of the natural lens; and   approximating a best fit curve for the posterior surface using the anterior lens surface, the lens thickness and a historical ratio between the anterior and posterior lens curvatures.