Friday, April 10, 2009

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 ┬Ám 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.