Bruch's Membrane

Bruch's membrane is the choroid's innermost layer. Because of its glassy microscopic appearance, it is also known as the vitreous lamina. It is 3–4 µm thick and lies snug behind the retina.

Bruch's membrane consists of five layers: 1) the basement membrane of the retinal pigment epithelium, which is the innermost layer; 2) the inner collagenous zone; 3) a central band of elastic fibers; 4) the outer collagenous zone; 5) the basement membrane of the choriocapillaris.

When the Bruch's membrane thickens with age, the transport of metabolites becomes slow, which results in a build up of drusen in age-related macular degeneration. There is also an accumulation of phospholipids deposits on and within the membrane.