What is the third layer from the choroidal side in Bruch's membrane?

What is the third layer from the choroidal side in Bruch's membrane?

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

Answer: (A)

The structure of Bruch's membrane from the choroid toward the retina is a defined sequence of five layers: basement membrane of the choriocapillaris, outer collagenous layer, elastic layer, inner collagenous layer, and the basement membrane of the RPE. Since you start at the choroidal side, the first is the basement membrane of the choriocapillaris, the second is the outer collagenous layer, and the third is the elastic layer. The elastic layer provides a flexible boundary within Bruch's membrane, contributing to its elastic properties. With aging, this layer can stiffen or calcify, which can influence diffusion between the choroid and the RPE and relate to macular changes. The remaining layers—inner collagenous layer and the RPE basement membrane—lie closer to the retina.