Drusen are known as the hallmark of age-related macular degeneration (AMD). These small, yellow deposits of protein and lipids develop between the retinal pigment epithelium (RPE) and Bruch’s membrane and are generated by the intense metabolic activity of the photoreceptors.

Daniel Hardiman-McCartney MBE FCOptom, Clinical Adviser for the College, says: “They are an accumulation of deposits. With age, the retina is less effective at taking away all the waste materials.” 

While a few small drusen are a natural sign of ageing, they can be much more significant. Numerous small drusen, or larger ones, can be a sign of progression towards AMD. NICE guideline NG82 on AMD classifies the level of risk of progression to AMD according to size of drusen and other contributory factors (see NICE guideline on drusen grading, below). 

Drusen take two forms: hard and soft, with the latter, soft drusen, carrying a higher risk of vision loss. Daniel says: “Hard drusen have hard edges and are scattered across the retina a bit like icing sugar. Soft drusen are larger, with ill-defined edges, and tend to be clustered.

“A lot of very healthy people who never get AMD have drusen. However, pretty much everyone who has macular degeneration, either dry or wet, will have them. They are a fundamental part of the mechanism of sight loss.”

Dry AMD “is really just a collection of lots of drusen coalescing, causing large areas of vision loss”.

Drusen are also linked to wet AMD. Shamina Asif MCOptom, an optometrist at Moores Opticians in Walsall and founder of the Optom Academy, says: “Soft drusen are a precursor to developing wet AMD. This is because there are certain metabolic changes taking place within soft drusen that are more likely to cause blood vessels to grow.”