Drusen

Drusen are extracellular deposits that accumulate between the retinal pigment epithelium (RPE) and Bruch's membrane in the posterior segment of the eye. They are common in aging and are a key feature of age-related macular degeneration (AMD). Drusen vary in size and appearance and are typically categorized as hard drusen (small, discrete) and soft drusen (larger, confluent).

Composition and origin: Drusen contain lipids, proteins including apolipoproteins and complement factors, and other extracellular components. They are thought to arise from impaired clearance of retinal waste and lipids across Bruch's membrane, leading to accumulation beneath the RPE. Soft drusen are more strongly linked with AMD progression than hard drusen.

Clinical significance: Drusen in themselves usually do not cause symptoms. Their presence, especially large soft drusen or confluent areas, increases the risk of progression to advanced AMD, which can be geographic atrophy or neovascular (wet) AMD.

Diagnosis: On dilated examination, drusen appear as yellowish-white deposits. Imaging modalities such as fundus photography and optical coherence tomography (OCT) show sub-RPE elevations; fluorescein angiography or OCT angiography can assess associated neovascularization or other AMD features.

Management and prognosis: There is no treatment to remove drusen. Management focuses on monitoring and risk reduction for AMD progression: smoking cessation, control of cardiovascular risk factors, and dietary measures. In those with intermediate or advanced AMD, antioxidant and zinc supplementation (AREDS/AREDS2) may reduce progression risk; neovascular AMD is treated with anti-VEGF injections.