Bruch's membrane is the innermost layer of the

choroid The choroid, also known as the choroidea or choroid coat, is a part of the uvea, the vascular layer of the eye, and contains connective tissues, and lies between the retina and the sclera. The human choroid is thickest at the far extreme rear ...

of the eye. It is also called the ''vitreous lamina'' or ''Membrane vitriae'', because of its glassy microscopic appearance. It is 2–4 μm thick.

Layers

Bruch's membrane consists of five layers (from inside to outside): #the

basement membrane The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between Epithelium, epithelial tissues including mesot ...

of the retinal pigment epithelium #the inner collagenous zone #a central band of elastic fibers #the outer collagenous zone #the

of the choriocapillaris The retinal pigment epithelium transports metabolic waste from the photoreceptors across Bruch's membrane to the choroid.

Embryology

Bruch's membrane is present by midterm in fetal development as an elastic sheet.

Pathology

Bruch's membrane thickens with age, slowing the transport of metabolites. This may lead to the formation of drusen in

age-related macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, som ...

. There is also a buildup of deposits (Basal Linear Deposits or BLinD and Basal Lamellar Deposits BLamD) on and within the membrane, primarily consisting of phospholipids. The accumulation of lipids appears to be greater in the central fundus than in the periphery. This build up seems to fragment the membrane into a lamellar structure more like puff-pastry than a barrier. Inflammatory and neovascular mediators can then invite choroidal vessels to grow into and beyond the fragmented membrane. This neovascular membrane destroys the architecture of the outer retina and leads to sudden loss of central vision – wet age related macular degeneration.

Pseudoxanthoma elasticum Pseudoxanthoma elasticum (PXE) is a genetic disease that causes mineralization of elastic fibers in some tissues. The most common problems arise in the skin and eyes, and later in blood vessels in the form of premature atherosclerosis. PXE is cau ...

myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include ...

and trauma can also cause defects in Bruch's membrane which may lead to choroidal neovascularization.

Alport's Syndrome Alport syndrome is a genetic disorder affecting around 1 in 5,000-10,000 children, characterized by glomerulonephritis, end-stage kidney disease, and hearing loss. Alport syndrome can also affect the eyes, though the changes do not usually affect v ...

, a genetic disorder affecting the alpha(IV) collagen chains, can also lead to defects in the Bruch membrane such as 'dot and fleck' retinopathy. Angioid streaks cause calcification, thickening and breaks in Bruch's membrane.

Eponym

Bruch's membrane was named after the German anatomist

Karl Wilhelm Ludwig Bruch Karl Wilhelm Ludwig Bruch (May 1, 1819 – January 4, 1884) was a German anatomist born in Mainz. In 1842 he earned his medical doctorate from the University of Giessen, and in 1845 he received his habilitation with a dissertation on rigor mortis ...

References

External links

Pictures
at National Eye Institute {{DEFAULTSORT:Bruch's Membrane Human eye anatomy