Sheep eye lens capsule with ligaments attached. The capsule is lifting off the lens showing cell fiber ends beneath.Microscope image of lens capsule in relation to lens cell types
The lens capsule is a component of the globe of the eye.[1] It is a clear elastic basement membrane similar in composition to other basement membranes in the body. The capsule is a very thick basement membrane[2] and the thickness varies in different areas on the lens surface and with the age of the animal. It is composed of various types of fibers such as collagen IV,[3]laminin, etc.[4][5][6] and these help it stay under constant tension.[7] The capsule is attached to the surrounding eye by numerous suspensory ligaments and in turn suspends the rest of the lens in an appropriate position. As the lens grows throughout life so must the capsule. Due to the shape of the capsule, the lens naturally tends towards a rounder or more globular configuration, a shape it must assume for the eye to focus at a near distance. Tension on the capsule is varied to allow the lens to subtly change shape to allow the eye to focus in a process called accommodation.
Early in embryonic development the lens capsule is highly vascularized but later during embryo development becomes avascular and transparent, serving as a diffusion barrier helping to protect the lens. It is permeable to low molecular weight compounds,[8] but restricts the movement of larger things like bacteria, viruses and large colloidal particles.[9] As the capsule contains the lens, it is clinically significant in regard to surgery of the lens. For example, it is used to contain new artificial lenses implanted after cataract surgery.
^Yanoff, Myron. (2009). "Lens". Ocular pathology. Sassani, Joseph W. (6th ed.). Edinburgh: Mosby/Elsevier. ISBN978-0-323-04232-1. OCLC294998596.
^DISCHE, Z; ZELMENIS, G (April 1965). "The Content and Structural Characteristics of the Collagenous Protein of Rabbit Lens Capsules at Different Ages". Investigative Ophthalmology. 4: 174–80. PMID14283010.