What is the vascular layer of the eye that lies between the retina and the sclera called?

The vascular layer of the eye that lies between the retina and the sclera is known as the choroid. This structure is primarily responsible for providing nourishment to the outer layers of the retina through its rich supply of blood vessels. The choroid is critical for the health and function of retinal cells, ensuring they receive the necessary oxygen and nutrients. Additionally, the choroid helps absorb light, reducing reflection within the eye, which aids in enhancing visual acuity.

The ciliary body, although also a part of the vascular layer, primarily functions to assist in lens accommodation and aqueous humor production rather than directly nourishing the retina. The iris is involved in regulating the amount of light entering the eye but is not positioned between the retina and sclera; it is located in front of the lens. The retina, on the other hand, is the light-sensitive layer that converts light into neural signals but is not a vascular structure itself. Therefore, the correct identification of the choroid as the vascular layer emphasizes its crucial role in supporting the retina against the backdrop of the surrounding sclera.