Autofluorescence characteristics of normal foveas and reconstruction of foveal autofluorescence from limited data subsets.
OBJECTIVE
To develop mathematical and geometric models of the nonuniform autofluorescence (AF) patterns of foveas of normal subjects and to reconstruct these models from limited subsets of data.


METHODS
Confocal scanning laser ophthalmoscope (cSLO) AF fundus images of normal maculae were obtained from both eyes of 10 middle-aged subjects. They were filtered and contrast enhanced, to obtain elliptical isobars of equal gray levels (GLs) and determine the isobars' resolutions, eccentricities, and angles of orientation. The original image data were fit with a mathematical model of elliptic quadratic polynomials in two equal zones: the center and the remaining annulus.


RESULTS
The AF images segmented into nested concentric GL isobars with GLs that increased radially from the least-fluorescent center. The mean isobar resolution was 31 +/- 7 mum. The geometric eccentricity of the ellipses increased from 0.42 +/- 0.12 centrally to 0.52 +/- 0.14 peripherally (P = 0.0005), with mean axes of orientation peripherally 97.12 +/- 15.46 degrees . The model fits to the complete image data had mean absolute normalized errors ranging from 3.6% +/- 3.7% to 7.3% +/- 7.1%. The model fits to small subsets (1% to 2% of total image data) had mean absolute errors ranging from 3.7% +/- 3.8% to 7.3% +/- 7.2%.


CONCLUSIONS
Normal AF fundus images show finely resolved, concentric, elliptical foveal patterns consistent with the anatomic distribution of fluorescent lipofuscin, light-attenuating macular pigment (MP), cone photopigment, and retinal pigment epithelial (RPE) pigment in the fovea. A two-zone, elliptic, quadratic polynomial model can accurately model foveal data. This model may be useful for image analysis and for automated segmentation of pathology.
Smith
R Theodore
RT
Department of Ophthalmology, Columbia University, New York, NY 10032, USA. rts1@columbia.edu
Koniarek
Jan P
JP
Chan
Jackie
J
Nagasaki
Takayuki
T
Sparrow
Janet R
JR
Langton
Kevin
K
D000328:Adult; D005260:Female; D005453:Fluorescence; D005584:Fovea Centralis / Q000033:anatomy & histology* / Q000737:chemistry; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008062:Lipofuscin / Q000032:analysis; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D010857:Pigment Epithelium of Eye / Q000737:chemistry; D012168:Retinal Pigments / Q000032:analysis
D008062:Lipofuscin; D012168:Retinal Pigments