Sclerotica

Sclerotica refers to the white, opaque, fibrous outer layer of the eyeball. It is the posterior five-sixths of the ocular tunics, which are the three concentric layers that make up the eye. The sclera's primary function is to protect the delicate inner structures of the eye and to maintain its shape. It is a tough, collagenous tissue that provides structural support.

The sclera is relatively avascular, meaning it has a poor blood supply, which contributes to its white appearance. However, it is dotted with numerous small openings through which blood vessels and nerves pass to supply the inner eye. The most prominent of these openings is the optic nerve canal, through which the optic nerve exits the eye.

The outer surface of the sclera is covered by a thin, transparent membrane called the conjunctiva, which also covers the inner surface of the eyelids. This membrane helps to keep the eye lubricated and protected from foreign particles. The sclera is innervated by branches of the ciliary nerves, which contribute to its sensation.

Disorders affecting the sclera can range from inflammation, known as scleritis, to thinning and protrusion, as seen in certain connective tissue diseases. Trauma can also damage the sclera, potentially leading to vision loss. Its structural integrity is crucial for proper visual function.