Purpose Autofluorescent (AF) material within drusen
has rarely been described and there is little knowledge
about origin and formation of these particles. Drusen
formation is still a relatively unknown process and
analysis of AF inclusions might be important for the
understanding of fundamental processes. Here we
present a detailed analysis of drusen containing AF
material using structured illumination microscopy (SIM),
which provides a lateral resolution twice as high as
conventional fluorescence microscopy.
Methods Eight histological retinal pigment epithelium
(RPE) sections obtained from eight human donor eyes
(76±4 years) were examined by SIM using laser light of
different wavelengths (488 nm, 568 nm). Drusen were
studied with regards to their size and shape. AF material
within drusen was analysed in terms of size, shape, AF
behaviour, and distribution across drusen.
Results A total of 441 drusen were found, of which
101 contained AF material (22.9%). 90.1% of these
drusen were smaller than 63 mm (mean: 35.65 mm
±2.38 mm) regardless of whether classified as hard or
soft drusen. AF particles (n=190) within drusen show
similar spectra compared with lipofuscin granules in RPE
cells. Up to 11 particles were found within a single
druse. Nearly all particles were located in the outer 2/3
of the drusen (85.94%).
Conclusions SIM allows studying AF particles within
drusen on a higher resolution level compared with
conventional fluorescence, multiphoton or even confocal
microscopy and therefore provides detailed insights in
drusen. Shape and autofluorescence analysis of the
material embedded in drusen suggest that these
particles originate from the overlaying RPE cells. |
