Are All Drusen The Same?

Are all drusen the same? While some drusen are the hallmark of age related macular degeneration, others can be associated with conditions such as pseudoxanthoma elasticum and best’s macular dystrophy. By localizing the level at which the drusen is present can help differentiate the types of drusen. The table below categorizes four different drusen patterns.

 Soft DrusenHard DrusenCuticular DrusenSubretinal Drusenoid Deposits
Synonyms  Basal Laminar Drusen– Reticular Pseudo-drusen- “Pseudodrusen visibleen lumiere bleue”
Size63 to ≥ 1000 μm < 63 μm50 to 75 μm Large Range of Sizes
LocationSub-RPE SpaceSub-RPE SpaceSub-RPE SpaceSub-Retinal Space*Deposits between the RPE and inner segment ellipsoid lines (stages 1 and 2), later breaking through the ellipsoid line (stage 3) and subsequently fading (Stage 4)1
DescriptionLarge pale-yellow “placoid or dome-shaped structures” Small, punctate, yellow nodulesMultiple, densely packed small yellow-white nodular drusen that hyper fluoresce during fluorescein angiography (“starry-sky” fundus) – Either dot-like or reticular deposits, more blue, or at least whiter, than conventional soft drusen.1– Found preferentially in the parafoveal region.1
Clinical Implications– Drusen characteristics correlated with progression to exudative maculopathy include drusen number (five or more), drusen size (larger than 63 μm in diameter), and confluence of drusen.2– Baseline drusen volume is an important predictor for the development of advanced AMD at 12 and 24 months of follow-up3– Small, hard drusen are common with a prevalence of 93.6% in subjects aged 43- 86 years in the Beaver Dam Eye study4–  Hard drusen are the only drusenoid deposits that are considered a normal consequence of age5– AMD may begin with hard drusen1– Patients with cuticular drusen have a better visual prognosis than those with typical AMD6,7– Retinal pigment epithelium abnormalities, AVLs, neovascularization, and GA occurred at a frequency of 47.5%, 24.2%, 12.5%, and 25%, respectively8– Occurrence of GA and neovascularization were important determinants of final visual acuity in eyes with the cuticular drusen phenotype (both P < 0.015)8 – Subretinal Drusenoid Deposits can infrequently appear in individuals with no other apparent pathology9– Usually occur in association with age-related macular degeneration and are highly correlated with end-stage disease sub-types, choroidal neovascularization and geographic atrophy4– Dot pseudodrusen were associated with neovascular AMD whilst confluent pseudodrusen were associated with geographic atrophy10 
Other Associated Conditions  – MPGN II or HUS1– CFH mutations1– Dominant Drusen1– Sorby’s fundus dystrophy9– Pseudoxanthoma elasticum9– Acquired vitelliform lesions9– Dominant Drusen1

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