The marginal veil (eng. Marginal Veil; stratum marginalis, striae marginalis) is a small layer of tissue that covers the inner surface of the choroid of the eye at the base of the pupil - the facial surface of the iris and ciliary body.
The marginal veil consists of endothelial cells and a thin layer of connective tissue between the endothelium and the retinal pigment epithelium, as well as a small number of mesenchymal cells. Although this structure was discovered relatively recently, scientists believe it may have played a role in the evolution of the eyeball.
In humans, the marginal veil can vary in thickness and density, which affects its function and the permeability of light rays that cannot penetrate it even through the smallest viewing angle. This explains the ability to observe only one-eighth of the visual field with the naked eye.
The function of the marginal veil is not known exactly, but it is believed that it is it that helps preserve the light-sensitive cells of the retina from destruction and protects against