What are Drusen?
Drusen are small yellowish colored deposits of cellular debris scattered around your retina, which is the light sensitive part of your eye that is crucial to your vision because of photoreceptors called rods and cones on its surface. Drusen can be found from an eye exam by an ophthalmologist during retinal imaging or cross section imaging. As they are tiny pebble like specks of condense proteins, polysaccharides and lipids, they can be detected as small dark circular spots in the retinal image or a bump when observing the cross section of the eye if the drusen seeps under the retina. How are they caused? These cellular debris develop from retinal cells improper disposal of waste causing build-up of debris within the eye. Some believe that drusen is formed as a result of axonal degeneration of the optic nerve where the optic nerve fiber, is broken or crushed. Although it has not been proven yet, it is also believed that they are more common among Caucasians and are believed to have an autosomal dominant pattern of inheritance with incomplete penetrance.
Typically, there are no symptoms to the presence of drusen which makes routine eye exams a crucial part of healthy vision care due to its risk of future vision loss. The size and number of drusen present on your retina is important. Logically, patients with larger amounts or sized drusen are more prone to vision loss due to the damaging of rods and cones of the eye. Patients can have progressive vision loss called geographic atrophy or immediate vision loss from the rapid blood cell growth and leakage caused by drusen called neovascularization. Drusen is a definitive precursor and may ultimately cause macular degeneration.
Once a patient is diagnosed with age related macular degenerations, or AMD, the patients has received damage to the macula, a small spot on the middle of the retina whose function is to provide sharp and central vision. The two types of macular degeneration are known as “dry” or “wet”. Dry macular degeneration is the most common where the tissue of the retina shrinks and pigments accumulate, what then can progress is wet macular degeneration which is where new blood vessels grow around and behind the macular which can cause bleeding. While 90% of macular degeneration is dry, the 10% of wet macular degeneration causes 90% of the blindness. Macular Degeneration increases in risks with age; usually with people over 50 years. Other risk factors that may increase your chances of speeding macular degenerations are smoking, high cholesterol and blood pressure levels and obesity. In addition, from a study of twins, some believe that both genetics and environmental factors affect the onset of macular degeneration.
Returning back to drusen development and vision loss, in its progress, the center of the field of vision slowly blurs or grows dim. Colors are still visible, but the details become unclear. This tends to happen over a period of years. Often, people don't notice the early stages, especially if the other eye is working fine. Since the presence of drusen is very asymptomatic, the rate of discovery is very incidental.
References:
https://www.brightfocus.org/macular/article/why-my-doctor-always-talking-about-drusen
https://visionaware.org/your-eye-condition/age-related-macular-degeneration-amd/wet-and-dry-amd/