Drusen are small, yellow deposits that form within the eye, often detected during a routine comprehensive eye exam. They are commonly associated with the natural process of aging, but their presence can signal an increased risk for more serious vision problems. Understanding drusen is a foundational step in preserving vision health. This knowledge helps eye care professionals monitor the health of the macula, the central part of the retina responsible for sharp, detailed vision.
What Exactly Are Drusen?
Drusen are accumulations of extracellular material, meaning they form outside of the cells. They are primarily composed of lipids (fatty proteins) and various cellular waste and debris. These deposits are located beneath the retina, nestled between the Retinal Pigment Epithelium (RPE) and the Bruch’s membrane.
The RPE is a layer of cells that nourishes the light-sensing cells of the retina and clears away metabolic waste. Drusen accumulate because the eye’s natural waste disposal system becomes less efficient with age, leading to a buildup of debris. This accumulation, which appears as tiny yellow spots, can interfere with the exchange of nutrients and oxygen between the underlying blood vessels and the retina.
Hard Versus Soft Drusen and Risk
Drusen are classified into two main types based on appearance, which indicates differing levels of risk. Hard drusen are typically small, round, and have distinct, well-defined borders. They are common in people over 40 and are generally considered a normal part of aging that rarely causes vision problems.
In contrast, soft drusen are larger, have indistinct or fuzzy borders, and often cluster together, sometimes merging into larger masses. Soft drusen, especially if numerous or large, are a stronger indicator of potential progression to a more serious eye condition. While hard drusen carry a low risk of vision loss, the risk can significantly increase (up to 50% over five years) for those with many intermediate and large soft drusen.
Drusen and Age-Related Macular Degeneration Connection
The accumulation of drusen is linked to the development of Age-Related Macular Degeneration (AMD), a leading cause of permanent central vision loss in older adults. When drusen build up under the macula, they disrupt the RPE’s function, starving the overlying photoreceptor cells of necessary nutrients and oxygen. This metabolic stress leads to the degeneration of the macula, which is the characteristic feature of AMD.
The progression of AMD is categorized by the size and number of drusen. Early AMD involves many small drusen or a few medium-sized ones. Intermediate AMD is characterized by many medium-sized or one or more large drusen. Advanced AMD, which causes significant vision loss, develops from these earlier stages and takes two forms:
Dry AMD (Geographic Atrophy)
This form involves the progressive thinning and atrophy of the macula, often where large drusen have coalesced.
Wet AMD (Neovascular AMD)
This form is preceded by drusen accumulation that leads to the growth of fragile, abnormal blood vessels under the retina, which can leak fluid and blood.
Monitoring and Management
A diagnosis of drusen is typically made during a comprehensive, dilated eye exam. If soft or numerous drusen are found, imaging tests like Optical Coherence Tomography (OCT) may be used to create detailed cross-sectional images of the retina and monitor the deposits. Since drusen cannot be treated directly, management focuses on slowing the progression from intermediate AMD to the advanced stages.
Lifestyle modifications are recommended for individuals with drusen, including smoking cessation, which can reduce the risk of progression by 25%. Dietary changes, such as incorporating foods rich in leafy green vegetables and fatty fish, are also encouraged. For those with intermediate AMD or advanced AMD in one eye, specific high-dose nutritional supplements, known as the AREDS 2 formulation, are often prescribed. This formulation includes:
- Lutein
- Zeaxanthin
- Vitamin C
- Vitamin E
- Zinc
- Copper
These supplements have been shown to reduce the risk of progression to advanced AMD by about 25%.