Scleral

Scleral is an adjective relating to the sclera, the tough, opaque fibrous layer that forms the white of the eye. The sclera provides most of the globe’s thickness and offers protection and mechanical support for internal structures, while remaining continuous with the transparent cornea at the limbus.

Anatomy: The sclera averages about 0.3 mm in thickness at the equator and thickens toward the posterior pole to over 1 mm. It consists mainly of densely packed collagen type I fibers with limited blood supply. The episclera is the vascular outer layer; the inner lamina fusca lies next to the choroid. The sclera anchors the extraocular muscles and helps resist intraocular pressure, contributing to the globe’s shape and integrity.

Function and clinical relevance: The sclera protects intraocular contents and defines the eye’s external contour. Pathologies include scleritis, an inflammatory condition that can be autoimmune or infectious, and scleral thinning seen in high myopia or connective tissue disorders, which can increase rupture risk. A blue tint can indicate scleral thinning or systemic conditions such as osteogenesis imperfecta.

Other uses and terminology: The term scleral also appears in descriptions of scleral contact lenses, which rest on the sclera rather than the cornea, and in surgical procedures such as scleral buckling for retinal detachment. Materials derived from sclera, such as scleral grafts, are used in reconstructive ocular surgery.