Differentiating drusen: Drusen and drusen-like appearances associated with ageing, age-related macular degeneration, inherited eye disease and other pathological processes

Abstract

Drusen are discussed frequently in the context of their association with age-related macular degeneration (AMD). Some types may, however, be regarded as a normal consequence of ageing; others may be observed in young age groups. They also occur in a number of inherited disorders and some systemic conditions. Whilst drusen are classically located external (sclerad) to the retinal pigment epithelium, accumulations of material internal (vitread to) this layer can display a drusen-like appearance, having been variously termed pseudodrusen or subretinal drusenoid deposits. This review first briefly presents an overview of drusen biogenesis and subclinical deposit. The (frequently overlapping) subtypes of clinically detectable deposit, seen usually in the context of ageing or AMD, are then described in more detail, together with appearance on imaging modalities: these include hard and soft drusen, cuticular drusen, reticular pseudodrusen and "ghost drusen". Eye disorders other than AMD which may exhibit drusen or drusen-like features are subsequently discussed: these include monogenic conditions as well as conditions with undefined inheritance, the latter including some types of early onset drusen such as large colloid drusen. A number of systemic conditions in which drusen-like deposits may be seen are also considered. Throughout this review, high resolution images are presented for most of the conditions discussed, particularly the rarer ones, providing a useful reference library for images of the range of conditions associated with drusen-like appearances. In the final section, some common themes are highlighted, as well as a brief discussion of some future avenues for research.

Cell-based therapeutic strategies for replacement and preservation in retinal degenerative diseases

“…Hard drusen are generally small and discrete yellow-white deposits whereas soft drusen are larger, pale-yellow, and dome-shaped in structure. Hard drusen are detected in both aged and AMD individuals, but the presence of soft drusen within the macula is correlated with higher rates of AMD (Ardeljan and Chan, 2013; Buch et al, 2005; Khan et al, 2016; Rudolf et al, 2008). Much of the categorization of AMD is based on the size and distribution of drusen, which can continue to enlarge and cause loss of RPE and photoreceptor cells (Schuman et al, 2009).…”

Fluorescence lifetimes of drusen in age‐related macular degeneration

“…4,8 They can be large enough to break through the ellipsoid line and disturb or shorten the overlying photoreceptors and form conical accumulations that can breach the external limiting membrane. Reticular pseudodrusen are especially visible in near infrared reflectance imaging and may appear hypofluorescent in fluorescein angiography.…”

“…Reticular pseudodrusen are especially visible in near infrared reflectance imaging and may appear hypofluorescent in fluorescein angiography. 4 Small drusen (<63 lm) can be a sign of normal retinal aging changes and are not associated with increased risk of late AMD …”

“…4,7 In the biomicroscopic fundus examination, drusen are seen as discrete, yellow-white punctuate elevations. Retinal drusen are focal deposits of extracellular debris located between the basal lamina of the RPE and the inner collagenous layer of the Bruch membrane and are mainly concentrated within the posterior pole.…”

Epidemiology of age-related macular degeneration (AMD): associations with cardiovascular disease phenotypes and lipid factors

“…Category 4 (AREDS4) refers to eyes exhibiting GA involving the central macula and/or CNV. (See Khan et al [16] for a detailed review of drusen and drusen-like deposits).

Fig. 1Progression of age-related macular degeneration.

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