method for detecting a functional signal in retinal images

Abstract

A system and method for detecting a functional signal in retinal images. An optical imaging device comprises a stimulation light source, an interrogating light source, and a detector. The retina is stimulated by the stimulation light source. The retina is then illuminated by an interrogation light, and the reflected intensity from the retina is measured at an interrogating spectral band that indicates the state of hemoglobin saturation before and after visual stimulation. The optical changes that result from retinal neuronal activity are captured by the detector. The signal representing the state of hemoglobin saturation before and after visual stimulation is isolated. In an embodiment of the present invention, this signal is isolated using principle components analysis (PCA). In another embodiment of the present invention, blind source separation (BSS) and independent component analysis (ICA) algorithms such as extended spatial decorrelation and fast-ICA are used to isolate the functional signal from the retinal videos.

1 . A method for detecting functional areas in retinal images comprising: 
 recording a pre-stimulation image of the retina in a non-stimulating wavelength region;    illuminating the retina using a stimulating wavelength using a variable illumination pattern;    illuminating the retina at a non-stimulating wavelength;    recording the reflectance of the retina in the non-stimulating wavelength region to form a post-stimulation image; and    determining functional areas of the retina based upon reflectance differences between the pre-stimulation image and the post-stimulation image.    
     
     
         2 . The method for detecting functional areas in retinal images of  claim 1  further comprising: 
 repeating the method to create a variable number of post stimulation images.    
     
     
         3 . The method for detecting functional areas in retinal images of  claim 1  wherein determining functional areas of the retina based upon reflectance differences between the pre-stimulation image and the post-stimulation images further comprises applying principal components analysis to the resulting reflectance differences to determine functional areas of the retina.  
     
     
         4 . The method for detecting functional areas in retinal images of  claim 3  wherein determining functional areas of the retina based upon reflectance differences between the pre-stimulation image and the post-stimulation images further comprises applying a fast-ICA algorithm to the resulting images to determine functional areas of the retina.  
     
     
         5 . The method for detecting functional areas in retinal images of  claim 3  wherein determining functional areas of the retina based upon reflectance differences between the pre-stimulation image and the post-stimulation images further comprises applying an extended spatial decorrelation algorithm to the resulting images to determine functional areas of the retina.  
     
     
         6 . A method for determining retinal hemoglobin saturation before and after stimulation comprising: 
 recording a pre-stimulation image of the retina in a non-stimulating wavelength region;    illuminating the retina using a stimulating wavelength using a variable illumination pattern;    illuminating the retina at a non-stimulating wavelength;    recording the reflectance of the of the retina in the non-stimulating wavelength region to form a post-stimulation image; and    determining hemoglobin saturation based upon reflectance differences between the pre-stimulation image and the post-stimulation image.    
     
     
         7 . The method for determining retinal hemoglobin saturation before and after stimulation of  claim 6  further comprising: 
 repeating the method to create a variable number of post stimulation images.    
     
     
         8 . The method for determining retinal hemoglobin saturation before and after stimulation of  claim 6  wherein determining hemoglobin saturation based upon reflectance differences between the pre-stimulation image and the post-stimulation images further comprises applying principal components analysis to the resulting reflectance differences to determine hemoglobin saturation.  
     
     
         9 . The method for determining retinal hemoglobin saturation before and after stimulation of  claim 6  wherein determining hemoglobin saturation based upon reflectance differences between the pre-stimulation image and the post-stimulation images further comprises applying a fast-ICA algorithm to the resulting images to determine hemoglobin saturation.  
     
     
         10 . The method for determining retinal hemoglobin saturation before and after stimulation of  claim 6  wherein determining hemoglobin saturation based upon reflectance differences between the pre-stimulation image and the post-stimulation images further comprises applying an extended spatial decorrelation algorithm to the resulting images to determine hemoglobin saturation.