What is the middle layer of Bruch's membrane?

What is the middle layer of Bruch's membrane?

• A. Elastic Layer
• B. Outer Collagenous Layer
• C. Inner Collagenous Layer
• D. Basement Membrane of the RPE

Answer: (A)

Bruch's membrane is a five-layer structure between the retinal pigment epithelium and the choroid, arranged from inner to outer as: the RPE basement membrane, the inner collagenous layer, the elastic layer, the outer collagenous layer, and the basement membrane of the choriocapillaris. The middle layer is the elastic layer, because it sits between the two collagenous layers and is rich in elastin fibers that give Bruch's membrane its characteristic elastic properties. This central layer helps maintain structural integrity while allowing some flexibility for diffusion between the retina and choroid. The inner collagenous layer lies closest to the RPE, and the outer collagenous layer lies closest to the choroid. With aging and disease, this elastic layer often thickens and calcifies, contributing to pathological changes in Bruch's membrane.

Bruch's membrane is a five-layer structure between the retinal pigment epithelium and the choroid, arranged from inner to outer as: the RPE basement membrane, the inner collagenous layer, the elastic layer, the outer collagenous layer, and the basement membrane of the choriocapillaris. The middle layer is the elastic layer, because it sits between the two collagenous layers and is rich in elastin fibers that give Bruch's membrane its characteristic elastic properties. This central layer helps maintain structural integrity while allowing some flexibility for diffusion between the retina and choroid. The inner collagenous layer lies closest to the RPE, and the outer collagenous layer lies closest to the choroid. With aging and disease, this elastic layer often thickens and calcifies, contributing to pathological changes in Bruch's membrane.