Fig 1.
Methodology for classifying LMS cones.
Representative examples of cone bleaching curves under a complete bleach from a dark adapted retina (A) and under a selective L and M-cone (B) bleach respectively are shown. Mean intensity timecourses for a given cone are accumulated together across all bleaching cycles. Non-linear least squares fit to the mean intensity of individual cones are shown and colored according to their peak sensitivity as blue, green or red for LMS cones respectively. The change in intensity under selective L- and M-cone bleaches for all L and M cones are plotted in (C) in a scatter plot. Each scatter point represents either an L or M cone. The x-y plot is converted to polar coordinates. The histogram of the angular coordinate is separared into respective L and M cone clusters by fitting a sum of 2 one-dimensional gaussian curves and taking the point of intersection of the component gaussians.
Table 1.
Cone optical properties and classification of cone-subtypes.
Fig 2.
LMS cone mosaics in the retinae of human subjects.
Each column represents an individual subject’s retina at 1.5 deg temporal eccentricity. The last column represents cone assignments for the protanopic subject. S-cones appear as a cluster of weakly reflecting cones under complete bleach starting from a dark adapted retina (top row). L and M cones appear as two distinct clusters of cones on the basis of their relative change in intensity under selective bleaches (middle row). No separation of such clusters are obtained in the protanope. Based on where a cone appears in the S vs L/M and L vs M clustering analysis, it is shaded as ‘blue’, ‘green’ and ‘red’ to represent S, M and L cones respectively (bottom row). Other than S-cones, cone assignments for the protanope are shaded as ‘green’ M-cones on the basis of previous verification of his color deficiency. The scale bar is 2 arc-min.
Fig 3.
Comparison of cone classification in the AO fundus camera (left) and SLO (right).
Cone assignments in the former are obtained from Hofer et al. 2005. Mismatched cones in the SLO image are marked as ‘circles’. Cones which have probability less than 0.9 to be reliably identified in the SLO and fundus are marked with ‘horizontal’ & ‘vertical’ lines respectively. The scale bar is 4 arc-min.