Characteristics of Drusens

Hard drusen, soft drusen, Small, intermediate, large drusen

1. Characteristics Of Drusens

2. AGE RELATED MACULAR
DEGENERATION
Two differentforms
NON-NEOVASCULAR orDRY AMD (80-90 %)
NEOVASCULAR or WET AMD (10-20%)
Only approximately 10% to 15% of patients with AMD
have severe central vision loss.
Atrophic AMD -25%
Exudative AMD -75%
The five-year incidence and progression of age-related maculopathy:
the Beaver Dam Eye Study. Ophthalmology. 1997;104:7-21.

3. Drusen
Drusen are focal deposits of extracellular material, lying
between the basal lamina of RPE and the inner collagenous
layer of Bruch’s membrane RETINA 30:1441–1454,
2010

4. Drusen Compositions
The largest single component is lipid,
principally esterified cholesterol, unesterified
cholesterol, and phosphatidylcholine, which is
thought to be derived from a large lipoprotein
of intraocular origin
carbohydrates
zinc
vitronectin, apolipoproteins E and B
components of the complement system
RETINA 30:1441–1454,

5. Pathogenesis
Themostprominentthreetheoriesare
1.TransformationtheoryofDonders
2.Deposition theoryofMuller
3.VasculartheoryofFriedman etal
Dondersproposedthatdrusenaretheproductofa
directconversionofthepigmentepithelium.
Mullersuggestedthatdrusenweredepositedbyan
otherwiseintactpigmentepithelium.

6. Abnormalities in the enzymatic activity of aged RPE cells lead to
accumulation of metabolic by-products.
Engorgement of RPE cells interferes with their normal cellular
metabolism
leading to extracellular excretion
In addition ,lipids are deposited in Bruch’s membrane
possibly from failure of RPE to process cellular debris
associated with outer segment turnover
Resulting hydrophobic barrier impede the passage of fluid
from retina to choroid causing detachment of RPE.
Breaks in Bruchs membrane are responsible for
from choriocapillaris
Drusen
neovascular
ingrowth
Deposition theory of Muller

7. Vascular model
Accumulation of lipids in the sclera and Bruch’s
membrane
increased hydrostatic pressure of choroidal vasculature,
impaired choroidal perfusion and reduced hydraulic
conductivity across Bruch’s membrane
results in
exudation and deposition of extracellular proteins and
lipids on the inner aspect of bruch’s membrane
manifest as
Friedman etal
basallineardepositsand
drusens

8. Drusens
HARD DRUSENS
SOFT /CONFLUENT
DRUSENS
•Small round discrete
yellowish white deposits
•Usually < 63 µm
•Large with indistinct
margins
•Drusens > 125 µm
considered to be soft

9. small (usually <64 µm in diameter)
intermediate (usually 64-124µm in diameter)
large (usually ≥125 µm in diameter)

10. Numerous cross-sectional and prospective
epidemiologic studies have demonstrated that
drusen diameter and area are a significant risk
factor for progression to advanced AMD; manual
analysis of drusen on color fundus photographs
shows only moderate correlation and is not
practical in clinical practice
Therefore, efforts are underway to use spectral
domain OCT for automated detection and
quantification of drusen
Surv Ophthalmol 57:389--414,
2012

11. By assessing drusen size, area, and volume
using multimodal imaging, it may be possible
to identify patients at high risk of disease
progression
Surv Ophthalmol 57:389--414,
2012

12. Evaluation with OCT

13. On SD-OCT, small and intermediate-size drusen
may be more clearly seen as discrete areas of
RPE elevation with variable reflectivity, reflecting
the variable composition of the underlying material
In larger drusen, or drusenoid pigment epithelium
detachment (PED), greater elevation of the RPE
may be seen, often dome-shaped, with a hypo-or
medium reflective material separating the RPE
from the underlying Bruch’s membrane

16. Drusen Variants
Cuticular drusens
Subretinal drusens

17. Cuticular drusen
Originally described as basal laminar drusen by
Gass in 1974
Basal laminar drusen were originally thought to
constitute focal nodular thickening of the RPE
basement membrane, although recent
histopathologic analysis suggests that their
features are indistinguishable from those of typical
drusen. Therefore, the descriptor ‘‘cuticular’’
drusen has now been widely adopted
Surv Ophthalmol 57:389--414,
2012

20. Subretinal Drusenoid Deposits
Originally termed as reticular pseudodrusen by
Mimoun et al in 1990 as a peculiar yellowish
pattern in the fundus of AMD patients, best seen
with blue light
In 1991 the same entity was termed ‘‘reticular
drusen’’ in the Wisconsin age-related maculopathy
grading system
With the advent of spectral domain OCT, it appears
that these drusen correspond to granular
hyperreflective material between the RPE and the
IS--OS junctions (i.e., they occur in the subretinal
space)

23. Optical properties
Both cuticular and soft drusen appear yellow
because of the removal of shorter wavelength light
by a double pass through the RPE
Subretinal drusenoid deposits, which are located
on the RPE, are not subjected to short-wavelength
attenuation and therefore are more prominent
when viewed with blue light
The location and morphology of extracellular
material in relationship to the RPE, and associated
changes to RPE morphology and pigmentation,
appears to be the primary determinants of druse
appearance in different imaging modalities
RETINA 30:1441–1454,
2010

26. Conclusion
Cuticular drusen, subretinal drusenoid deposits,
and soft drusen are composed of common
components
They are distinguishable by multimodal imaging
because of differences in location, morphology,
and optical filtering effects by drusenoid material
and the RPE

27. AMD classification:

28. OCT
A) cube scan
B) Central line scan, high resolution
C) High resolution raster scans of the fovea,
superior macula, and inferior macula.

29. OCT

30. FUNDUS PHOTO

31. THANK YOU