Method and device for measuring an optical lens for individual wearing situations by a user

Abstract

An apparatus for measuring a cornea of a subject contains an image capturing device configured to capture image data of an iris of the subject from a plurality of viewpoints by imaging beam paths which pass through the cornea and a computing unit for providing a mathematical model of an anterior eye section of the subject including a mathematical model of the cornea and the iris. The model further identifies and registers image features of the iris, which are present in a plurality of images of the image data; determines deviations between actual positions of the image features of the iris in the images captured from the plurality of viewpoints and expected positions of the image features of the iris in the images captured from the plurality of viewpoints in consideration of the mathematical model of the cornea and the position of the iris.

1 . An apparatus for measuring a cornea of a subject, the apparatus comprising:
 an image capturing device configured to capture image data of an iris of the subject from a plurality of viewpoints by imaging beam paths which pass through the cornea; and   a computing unit configured to:
 provide a mathematical model of an anterior eye section of the subject including a mathematical model of the cornea and the iris; 
 identify and register image features of the iris, which are present in a plurality of images of the image data; 
 determine deviations between actual positions of the image features of the iris in the images captured from the plurality of viewpoints and expected positions of the image features of the iris in the images captured from the plurality of viewpoints in consideration of the mathematical model of the cornea and the position of the iris; 
 adapt parameters of the mathematical model of the cornea so as to minimize the deviations; and 
 determine a metric of the cornea from the adapted mathematical model of the cornea. 
   
     
     
         2 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to evaluate a refractive power or an astigmatism from the adapted mathematical model of the cornea. 
     
     
         3 . The apparatus as claimed in  claim 1 , wherein the mathematical model comprises a relative position of the iris with respect to the cornea. 
     
     
         4 . The apparatus as claimed in  claim 1 , wherein the apparatus is configured to calculate the cornea situated between the iris and the image capturing device without prior knowledge about how the iris looks. 
     
     
         5 . The apparatus as claimed in  claim 1 , wherein the apparatus is configured to perform a correlation of previously unknown image features in images of the iris recorded from different viewpoints. 
     
     
         6 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to calculate the shape of the cornea based on a system of equations from imaging beam paths which are captured at the respective known positions. 
     
     
         7 . The apparatus as claimed in  claim 1 , wherein the image capturing device comprises:
 a first camera configured to capture first image data from a first viewpoint; and   a second camera configured to capture second image data from a second viewpoint,   wherein the computing unit is configured to determine the three-dimensional shape of the cornea on the basis of the first image data and the second image data.   
     
     
         8 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to iteratively determine the three-dimensional shape of the cornea with an integration method. 
     
     
         9 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to determine the three-dimensional shape of the cornea on a basis of back tracing the respective imaging beam paths entering the image capturing device. 
     
     
         10 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to determine the three-dimensional shape of the cornea by dividing at least one of a front surface or a back surface of the cornea into surface elements and to determine an alignment of the surface elements. 
     
     
         11 . The apparatus as claimed in  claim 10 , wherein the computing unit is configured to determine a three-dimensional shape of the front surface and the back surface of the cornea on the basis of the alignment of the surface elements. 
     
     
         12 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to determine the three-dimensional shape of the cornea taking account of a boundary condition that a front surface or a back surface of the cornea has a parameterizable area. 
     
     
         13 . The apparatus as claimed in  claim 12 , wherein the parameterizable area includes a sphere, a section of the sphere, a torus, or a section of the torus. 
     
     
         14 . The apparatus as claimed in  claim 1 , wherein the computing unit is further configured to determine the three-dimensional shape of the cornea taking account of one or more known contact points of the cornea. 
     
     
         15 . The apparatus as claimed in  claim 1 , wherein the computing unit is configured to determine a spatial refractive index distribution of the cornea to be measured. 
     
     
         16 . A method for measuring the cornea of a subject, the method comprising the steps of:
 capturing image data of an iris of the subject from a plurality of viewpoints by imaging beam paths which pass through the cornea;   providing a mathematical model of an anterior eye section of the subject including a mathematical model of the cornea and the iris;   identifying and registering image features of the iris, which are present in a plurality of images of the image data;   determining deviations between actual positions of the image features of the iris in the images captured from the plurality of viewpoints and expected positions of the image features of the iris in the images captured from the plurality of viewpoints in consideration of the mathematical model of the cornea and the position of the iris;   adapting parameters of the mathematical model of the cornea so as to minimize the deviations; and   determining a metric of the cornea from the adapted mathematical model of the cornea.   
     
     
         17 . The method of  claim 16 , further comprising a preceding step of calibrating the camera system for capturing the image date of the iris from the plurality of viewpoints. 
     
     
         18 . A computer program product being stored on a non-transitory storage medium and comprising instructions that, upon execution of the program by a computer, cause the computer to perform the method of  claim 16 .