Sclera Sclera The sclera, also known as the white of the eye, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some elastic fiber. In humans, the whole sclera is white, contrasting with the coloured iris, but in other mammals the visible part of the sclera matches the colour of the iris, so the white part does not normally show. In the development of the embryo, the sclera is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, fatty deposits on
Book of the Ten Treatises of the Eye means for medieval ophthalmologists in the West to come into contact with the work of Galen. There are four essential doctrines that shape Hunayn's dissertation on vision and the anatomy of the eye: Hunayn relies on these principles to build up his conception of vision, which incorporates the anatomy of the eye in a way that makes discussion of one without the other unproductive. The structure of the eye is presented as a hierarchy, starting first with the part that is most directly responsible for sight, and working down towards the parts which exists only to facilitate this function. The