sclera

This term refers specifically to the opaque, fibrous layer of the eye, often referred to in common parlance as the white of the eye. It serves as a structural support system, ensuring the eyeball remains spherical despite the internal pressure of the vitreous humor. In medical and anatomical contexts, the word is treated as a countable noun, though it is frequently discussed in the singular when referring to the general tissue type. It is distinct from the cornea, which is the transparent front portion of the same outer layer.