June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Fundus autofluorescence from drusen is spectrally different from that of lipofuscin
Author Affiliations & Notes
  • Martin Hammer
    Dept of Ophthalmology, University of Jena, Jena, Germany
  • Lukas Kreilkamp
    Dept of Ophthalmology, University of Jena, Jena, Germany
  • Lydia Sauer
    Dept of Ophthalmology, University of Jena, Jena, Germany
  • Thomas Ach
    University hospital Würzburg, Würzburg, Germany
  • Theodore Smith
    New York University School of Medicine, Department of Ophthalmology, New York, New York, United States
  • Christine Curcio
    Department of Ophthalmology, University of Alabama School of Medicine, Birmingham, Alabama, United States
  • Footnotes
    Commercial Relationships   Martin Hammer, None; Lukas Kreilkamp, None; Lydia Sauer, None; Thomas Ach, None; Theodore Smith, None; Christine Curcio, None
  • Footnotes
    Support  DFG Ha 4430/3-1
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 48. doi:
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      Martin Hammer, Lukas Kreilkamp, Lydia Sauer, Thomas Ach, Theodore Smith, Christine Curcio; Fundus autofluorescence from drusen is spectrally different from that of lipofuscin. Invest. Ophthalmol. Vis. Sci. 2017;58(8):48.

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

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Abstract

Purpose : Histology studies have shown a distinct difference in the autofluorescence spectral and temporal characteristics of drusen and lipofuscin of retinal pigment epithelium (RPE)1-3. We determined if spectral differences between lipofuscin and drusen autofluorescence could be detected in vivo.

Methods : 50 eyes in 43 patients (mean age: 73.5±8.3 years), suffering from non-exudative age related macular degeneration (AMD), were investigated by fluorescence lifetime ophthalmoscopy (FLIO, Heidelberg Engineering). Fluorescence was excited at 473 nm and recorded in two spectral channels: 498-560 nm and 560-720 nm. The intensity ratio of the short and the long wavelength emission (spectral ratio), giving a relative measure of spectral fluorescence emission, was determined. Drusen were segmented from autofluorescence intensity images and color fundus photographs and spectral ratios were averaged over drusen and non-drusen areas. In order to include data from the posterior pole only, measurements were restricted to the area of the ETDRS-grid, centered at the macula. In a subgroup analysis, hard and soft were distinguished.

Results : Spectral ratios of all drusen were significantly higher than that of non-drusen areas (0.64±0.13 vs. 0.56±0.08, p<0.0005) indicating a green-shift of the drusen fluorescence compared to that of lipofuscin (fig.1). The green-shift was higher in the soft drusen than in the hard drusen (spectral ratio 0.65±0.14 vs. 0.57±0.05, p=0.012).

Conclusions : Although our method does not record full spectra, it clearly shows a hypsochromic shift of drusen fluorescence compared to that of lipofuscin. This is in agreement with recent ex vivo hyperspectral histology data demonstrating a green autofluorescence spectrum specific to drusen 1, 3, 4. The shift is expected to be even greater for drusen in isolation since our in vivo measurement at the druse records a mixture of druse emission and that of the overlying RPE. These data show that drusen contain other fluorophores than those in RPE lipofuscin. Possibly, there is also a different fluorophore composition in hard and soft drusen.
References:
1. Marmorstein et al. IOVS 2002;43:2435-2441.
2. Schweitzer et al. IOVS2012;53:3376-3386.
3. Tong et al. Retina 2016, doi 10.1097/IAE.0000000000001325
4. Ben Ami et al TVST 2016;5:5.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Fig. 1: Fluorescence intensity (left) and spectral ratio (right, blue color of drusen indicate shorter emission wavelengths).

Fig. 1: Fluorescence intensity (left) and spectral ratio (right, blue color of drusen indicate shorter emission wavelengths).

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