Which layer of the eye is primarily responsible for nutrition and blood supply?

The middle vascular layer of the eye, also known as the uvea, plays a crucial role in providing nutrition and blood supply. This layer consists of three components: the iris, ciliary body, and choroid. The choroid is particularly significant as it is rich in blood vessels, supplying oxygen and nutrients to the outer layers of the retina and providing essential support to other structures within the eye.

In contrast, the outer fibrous layer primarily consists of protective structures, such as the cornea and sclera, and does not play a significant role in nutrition or blood supply. The inner neural layer, which includes the retina, is responsible for processing visual information but relies on the vascular supply from the middle layer for its nutritional needs. The cornea, though important for light refraction and transparency, is avascular (lacks blood vessels) and receives nutrients from the tear film and aqueous humor, rather than from blood supply. Therefore, the middle vascular layer is correctly identified as the main source of nutrition and blood supply in the eye.