The crystalline lens is an avascular, elastic, disc-shaped biconvex structure located posterior to the iris and anterior to the vitreous body in the posterior chamber. In the adult eye, the lens measures approximately 9–10 mm in diameter equatorially and 5–6 mm antero-posteriorly (Fig 9-1). It is derived from surface ectoderm. See BCSC Section 11, Lens and Cataract, for in-depth discussion of the structure, embryology, and pathology of the lens.
The capsule, which surrounds the lens, is a thick basement membrane elaborated by lens epithelial cells and composed partly of type IV collagen fibers (Fig 9-2). The lens capsule is thickest anteriorly (12–21 μm) and peripherally near the equator and thinnest posteriorly (2–9 μm) (Fig 9-3).
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.