Bruch's membrane

• It is the innermost layer of the choroid
• 2-4 microns in thickness
• elastic mucoprotein membrane
• Lies between the retina pigment epithelium and the layer of choriocapillaris
• Alternate name – lamina vitrea

Development – outer part develops from the mesoderm while the inner part develops from ectoderm

It is divided into 5 layers:

1. Outer choroidal layer composed of endothelial cells of the choriocapillaris
2. Outer collagenous zone (OCZ)
3. Layer of fenestrated elastic fibers
4. Inner collagenous zone (ICZ)
5. Basement membrane of Retinal pigment epithelium

Clinical importance:

• The bruch’s membrane is involved in the pathogenesis of age related macular degeneration