Drusen is the accumulation of fatty deposits under the retina of the eye, which is the part of the eye that senses light. Drusen deposits come in hard and soft types and appear as yellow spots when viewed by an eye doctor with the right tools. People with drusen deposits do not normally display any symptoms and can only be diagnosed with them during routine eye examinations.
Soft and hard drusen are distinguished by how clear the edges of the deposits are. Hard drusen, which manifests as small and distinct yellow spots spread out far apart, may not create any symptoms in a patient at all. Soft drusen in tight enough clusters and high enough numbers are a good indicator of age-related macular degeneration, an eye disease that slowly degrades one's ability to see. While dry macular degeneration is untreatable with current methods, wet macular degeneration may be treated if caught soon enough.
Macular degeneration is described as the macula, the area of the eye responsible for catching light, degrading. Wet macular degeneration is caused by distortions in the macula, while dry macular degeneration is caused by atrophy of the macula. This means that damage from dry macular degeneration may be incurable as of 2015, as there is not yet an effective method for restoring the damage done by dry macular degeneration.