April 2010
Volume 51, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2010
Statistical Analysis of Reproducibility of Fluorescence Decay Histograms at the Fundus
Author Affiliations & Notes
  • M. Klemm
    Biomedical Engineering & Informatics, Ilmenau University of Technology, Ilmenau, Germany
  • A. Dietzel
    Biomedical Engineering & Informatics, Ilmenau University of Technology, Ilmenau, Germany
  • E. Nagel
    Ophthalmology Practice, Rudolstadt, Germany
  • D. Schweitzer
    Experimental Ophthalmology, University of Jena, Jena, Germany
  • U. Graichen
    Biomedical Engineering & Informatics, Ilmenau University of Technology, Ilmenau, Germany
  • J. Haueisen
    Biomedical Engineering & Informatics, Ilmenau University of Technology, Ilmenau, Germany
  • Footnotes
    Commercial Relationships  M. Klemm, None; A. Dietzel, None; E. Nagel, None; D. Schweitzer, None; U. Graichen, None; J. Haueisen, None.
  • Footnotes
    Support  German Ministry of Science, Grant 03IP605
Investigative Ophthalmology & Visual Science April 2010, Vol.51, 2293. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      M. Klemm, A. Dietzel, E. Nagel, D. Schweitzer, U. Graichen, J. Haueisen; Statistical Analysis of Reproducibility of Fluorescence Decay Histograms at the Fundus. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2293.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose: : To determine the reproducibility of fluorescence lifetime imaging (FLIM) measurements in ophthalmology on the basis of an evaluation of fluorescence decay photon histograms.

Methods: : To measure the fluorescence lifetime at the human fundus a modified Heidelberg Retina Angiograph was used. The endogenous fluorophores were excited by a diode laser with pico-second pulses at 446 nm and a repetition rate of 80 MHz. The auto-fluorescence was detected in two spectral channels: 490-560 nm and 560-700 nm using the time-correlated single photon counting method. A time resolution of approximately 12.2 ps was achieved by dividing the time between laser pulses (12.5 ns) into 1024 time channels. The acquired images cover 30° of the fundus with a lateral resolution of 40 x 40 µm². For this study six healthy male subjects aged between 25 and 35 years were examined. Each subject was measured twice per day (with one hour break in-between) on two days a week over three weeks resulting in a total of ten datasets per subject. Three regions (fovea centralis; a blood vessel free region of the papilla-macula-bundle; optic disc) each with a size of 15 x 15 pixels were manually selected and binned into a single fluorescence decay photon histogram. In those histograms the offset (background and detector dark current) was subtracted, the pre-stimulus part was removed and the maxima were normalized. A two-sample Kolmogorov-Smirnov (KS) test was performed for all unique permutations of the ten repetitive measurements separately for each spectral channel at a 5 % significance level.

Results: : The KS test showed that the measured photon distributions were significantly different in the short wavelength channel for about 6 % and in the long wavelength channel for about 8 % over all regions and subjects. The largest differences occurred in the optic disc region (12 % on average) due to the generally low photon counts while the smallest differences occurred in the macula region (1 % on average). Comparing both spectral channels with the KS test stated in about 95 % of the cases different distributions proving that there is different information in both channels. The comparison of the first and the second measurement per day did not reveal significant differences.

Conclusions: : The reproducibility of this new method for functional diagnostics of metabolic changes allows for the reliable application of subsequent analysis and diagnosis methods.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • metabolism • laser 
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×