Excitation-time-dependent increment in the luminescence of fundus autofluorescence.

Abstract

To investigate the excitation-time-dependent increment in luminescence of fundus autofluorescence. Fundus autofluorescence (FAF) images were obtained with a confocal scanning laser ophthalmoscope. Consecutive 60 images of each eye were taken at 1 s time intervals immediately after the beginning of argon laser excitation. Twenty-one eyes of 21 normal subjects were enrolled in the study. To analyse the luminescence of fundus autofluorescence, an 80 x 80 pixel square selection was placed in a relatively avascular fundus area of each consecutive image. Individual grey-scale values of the selected areas were recorded, and the time slope was plotted. The time-dependent increment of the autofluorescence was observed in all subjects. The average luminosity value of subjects at the beginning was calculated as 32.5 mean grey value (MGV), and luminosity reached its maximum (45.4 MGV) between 25 and 30 s. The excitation-time-dependent increment in FAF luminosity should be taken into account while acquiring FAF images for quantitative, comparative and longitudinal studies.