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
Vitreous body wide array of proteins. Despite having little solid matter, the fluid is substantial enough to fill the eye and give it its spherical shape. The lens, on the other hand, is tightly packed with cells. The vitreous humour has a viscosity two to four times that of water, giving it a gelatinous consistency. It has a refractive index of 1.336. The vitreous fluid is not present at birth (the eye being filled with only the gel-like vitreous "body"), but found after age 4-5, and increases in size thereafter. Produced by cells in the non-pigmented portion of the ciliary body, the