Lens at a glance
- What it is
- The lens is a transparent, biconvex structure behind the iris that focuses light on the retina.
- Location
- It sits behind the iris and pupil and in front of the vitreous body, held by zonular fibres from the ciliary body.
- Function
- It fine-tunes focus by changing shape (accommodation), when the ciliary muscle contracts and the lens becomes more curved.
- Body system
- Eye & ear · paired (left and right)
- FMA ID
- FMA58243 (Foundational Model of Anatomy)
Key facts
- Avascular and enclosed in a capsule.
- Becomes less flexible with age (presbyopia).
- It is about 10 mm across and keeps growing throughout life by adding fibres at its equator.
- It provides roughly a third of the eye's focusing power at rest; the cornea provides the rest.
Clinical relevance
Clouding of the lens is a cataract.
Structures next to the lens
The nearest named structures in the 3D model, measured from the centre of each part:
- Suspensory ligament of lens · skeletal
- Corona ciliaris · eye & ear
- Iris · eye & ear
- Anterior chamber of eyeball · eye & ear
- Cornea · eye & ear
- Tarsal plate of upper eyelid · eye & ear
- Tarsal plate of lower eyelid · eye & ear
- Choroid · eye & ear
- Sclera · eye & ear
- Vitreous body · eye & ear
References
- Foundational Model of Anatomy: Lens (FMA58243). EMBL-EBI Ontology Lookup Service.
- OpenStax. Anatomy and Physiology 2e, §14.1 Sensory Perception. Rice University, 2022.
- Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.
Related anatomy
Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.