The immune system is designed to fight off infections. To do this, it must be able to tell the difference between our own cells (and leave them alone) versus invading bacteria or viruses (and attack them). As we age, our cells are altered by “oxidative” damage and accumulation of debris (i.e environmental toxins like sun, chemicals, tobacco smoke, and other pollution), which can cause the immune system to attack its own cells.


immune cells interacting with blood vessels in an animal retina.

Drusen Formation

As the eye ages, it becomes less efficient at removing waste. 

Deposits of extracellular waste products containing fats and proteins are known as drusen.   When spotted on a comprehensive eye exam, drusen often are the first sign of age-related macular degeneration (AMD),

An increase in the number and size of drusen can cause the immune system to kick into overtime. When these deposits collect within and beneath the retinal pigment epithelium (RPE) cell layer they can trigger an out-of-control immune response.

Ultimately, this reaction may reach a tipping point and damage cells in the macula, the central part of the eye which provides sharp central vision.


A retina with drusen deposits.
Clinical photo courtesy of Jacque Duncan, MD, UCSF Department of Ophthalmology
Drusen in the retina.
Clinical photo courtesy of Jacque Duncan, MD, UCSF Department of Ophthalmology.

The risk of future vision loss is related to the number and size of the drusen. People with more drusen, and larger drusen, are at higher risk than those with fewer, smaller drusen. Drusen are categorized as small, intermediate, and large.