Book of the Ten Treatises of the Eye the sclera, a thick, hard membrane which protects the inner parts of the nerves from injury. The chorioid, a thin and soft structure filled with veins and arteries, follows next and provides nourishment to the overall structure. Finally, the retina transmits nutrients to the lenses themselves. Hunayn then presents the system responsible for protecting the eye. From the outermost level, these are the conjunctiva, cornea, and uvea. While both the conjuctiva and cornea provide protection with minimizing hindrance to the lenses, the uvea has an extra function of concentrating the pneuma exiting out of the eye to prevent it from
Ocelloid hypothesized to represent the eye of a multicellular organism coincidentally engulfed by a single-celled organism. The possibility that it had an evolutionary relationship to plastids had been considered at least since the 1970s, although until the 2010s direct evidence was scarce. Ocelloids contain subcomponents analogous to eye structures including the lens, cornea, iris, and retina. It can be divided into two substructures, the translucent, roundish "hyalosome" and the heavily pigmented "melanosome", also known as the retinal body or pigment cup. The hyalosome serves as the refractive lens of the ocelloid; it is surrounded by a layer of mitochondria serving as