Method and apparatus for image-based eye tracking for retinal diagnostic or surgery device

Abstract

An eye tracking method for determining a position of an eye or a part of an eye in an image of an image sequence by performing a comparison between said image and a reference image, said process including: aligning a set of images; computing an enhanced reference image based on a combination of said set of aligned images; and determining said position in said image of said image sequence by comparing said image of said image sequence and said enhanced reference image to yield a motion estimation between said reference image and said image of said sequence.

What is claimed is: 
     
         1 . A method of enhancing the video display of an image of an eye or a portion of an eye, said method comprising:
 aligning a sequence of images which are preceding an actual image of said video stream with respect to said actual image;   combining the resulting aligned set of images into an enhanced image to be used as a basis for an enhanced actual image of said video stream.   
     
     
         2 . The method of  claim 1 , wherein for each actual image of said video stream the display is based on said enhanced image resulting of a combination of aligned images preceding said actual image. 
     
     
         3 . The method of  claim 1 , further comprising:
 aligning said images of said preceding sequence based on eye tracking information.   
     
     
         4 . The method of  claim 3 , wherein said tracking information is obtained based on an enhanced reference image as defined in  claim 1 . 
     
     
         5 . A method for operating a diagnostic or surgical device based on eye tracking, said method comprising:
 determining whether an anomaly is detected during said eye tracking;   if an anomaly is detected during said eye tracking, putting said diagnostic or surgical device in a HOLD mode and/or   re-performing the operation of said diagnostic or surgical device for those parts of the eye where an anomaly has been detected.   
     
     
         6 . The method of  claim 5 , wherein said anomaly is one of the following:
 a change in image quality beyond a certain threshold;   a fast movement of the eye the speed of which is beyond a certain threshold;   a blurring of the image used for eye tracking;   a blurring of the image used for eye tracking in combination with a fast movement;   a cumulated difference between subsequent tracking images lying beyond a certain threshold;   a tracking error which is detected based on one or more images being considered statistically as outliers;   a sequence of images with a highs speed retinal movement;   an image sequence pattern representing a saccade;   an image sequence pattern representing a blink.   
     
     
         7 . The method of  claim 5 , wherein said determination whether an anomaly is detected is performed in realtime, and if an anomaly is detected said diagnostic or surgical device is put into a HOLD mode. 
     
     
         8 . The method of  claim 5 , wherein said anomaly during eye tracking is based on retrospectively evaluating images which have been obtained during eye tracking to identify anomalies, said method further comprising:
 reperforming the operation of said surgical or diagnostic device on those locations for which anomalies have been detected.   
     
     
         9 . The method of  claim 8 , wherein said retrospective evaluation comprises:
 comparing image sequences obtained during operation of said surgical or diagnostic device with eye movement patterns representing common eye movements to detect said anomalies.   
     
     
         10 . An apparatus for enhancing the video display of an image of an eye or a portion of an eye, said apparatus comprising:
 a module for aligning a sequence of images which are preceding an actual image of said video stream with respect to said actual image;   a module for combining the resulting aligned set of images into an enhanced image to be used as a basis for an enhanced actual image of said video stream.   
     
     
         11 . The apparatus of  claim 10 , wherein for each actual image of said video stream the display is based on said enhanced image resulting of a combination of aligned images preceding said actual image. 
     
     
         12 . The apparatus of  claim 10 , further comprising:
 a module for aligning said images of said preceding sequence based on eye tracking information.   
     
     
         13 . The apparatus of  claim 12 , wherein said tracking information is obtained based on an enhanced reference image as defined in claim  20 . 
     
     
         14 . An apparatus to be used in connection with a diagnostic or surgical device which operates based on eye tracking, said apparatus comprising:
 a module for determining whether an anomaly is detected during said eye tracking; and   a module for if an anomaly is detected during said eye tracking, putting said diagnostic or surgical device in a HOLD mode and/or   a module for re-performing the operation of said diagnostic or surgical device for those parts of the eye where an anomaly has been detected.   
     
     
         15 . The apparatus of  claim 14 , wherein said anomaly is one or more of the following:
 a change in image quality beyond a certain threshold;   a fast movement of the eye the speed of which is beyond a certain threshold;   a blurring of the image used for eye tracking;   a blurring of the image used for eye tracking in combination with a fast movement;   a cumulated difference between subsequent tracking images lying beyond a certain threshold;   a tracking error which is detected based on one or more images being considered statistically as outliers;   a sequence of images with a highs speed retinal movement;   an image sequence pattern representing a saccade;   an image sequence pattern representing a blink.   
     
     
         16 . The apparatus of  claim 14 , wherein said determination whether an anomaly is detected is performed in realtime, and if an anomaly is detected said diagnostic or surgical device is put into a HOLD mode. 
     
     
         17 . The apparatus of  claim 14 , wherein said anomaly during eye tracking is based on retrospectively evaluating images which have been obtained during eye tracking to identify anomalies, said apparatus further comprising:
 a module for reperforming the operation of said surgical or diagnostic device on those locations for which anomalies have been detected.   
     
     
         18 . The apparatus of  claim 17 , wherein said retrospective evaluation comprises:
 comparing image sequences obtained during operation of said surgical or diagnostic device with eye movement patterns representing common eye movements to detect said anomalies.