Opthalmology

Unit 7: Gradual Loss of Vision

1: Cataract

The Lens

The lens is located behind the iris and in front of the vitreous body in the anterior segment of the eye. It is held in position by spoke-like lens zonules that attach to its outer equator. It is a transparent, bi-convex structure.

anatomy of the lens

Anatomy of the lens

Adapted from: Drawing of the Eye, National Eye Institute, National Institutes of Health, used under CC BY 2.0 / Lens label highlighted.

the crystalline lens

The crystalline lens

Source: National Eye Institute, National Institutes of Health

The lens is composed of 3 parts:

  1. The capsule (a thin, elastic, outermost basement membrane)
  2. The cortex (outer layer of lens epithelial cells)
  3. The nucleus (central lens fibres)