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Capsule of lens

December 15, 2023

The lens capsule is a component of the globe of the eye.[1] It is a clear elastic basement membrane composed of collagen IV[2] laminin etc. [3][4] a quality that keeps it under constant tension.[5] As a result, 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. The lens capsule is the thickest basement membrane in the body.[6]

Capsule of lens
The upper half of a sagittal section through the front of the eyeball. (Capsule of lens labeled at center right.)
Details
Identifiers
Latincapsula lentis
MeSHD007903
TA98A15.2.05.007
FMA58881
Anatomical terminology
[edit on Wikidata]
Sheep eye lens capsule with ligaments lifting off lens showing fiber ends beneath.
Microscope image of lens capsule in relation to lens cell types

Normally, the lens capsule serves as a diffusion barrier. It is permeable to low molecular weight compounds[7] but restricts the movement of large colloidal particles.[8]

Anatomy edit

The lens capsule is a transparent membrane that surrounds the entire lens. The capsule is thinnest at the posterior pole with approximate thickness of 3.5μm. Average thickness at the equator is 7μm.[5][9] Anterior pole thickness increases with age from 11-15μm. The thickest portion of is annular region surrounding the anterior pole. This will also increases with age (from 13.5-16μm).[10] The ligaments suspending the lens form attachments in the equatorial area and more so just to the front and back of the equator.[11] There are tens of thousands of these ligaments in a mouse lens and for the most part they appear to connect directly to the lens capsule.[12]

 
Dissected equator of sheep eye lens showing capsule where ligaments attach.
 
Ligament connection to mouse capsule forming part of the Zonule of Zinn with associated cells and "feet"

As the lens grows throughout the life of most vertebrates the capsule is required to grow as well.[13] Some ligament anchors have associated cells where they connect to the lens capsule with periodic cellular processes penetrating the capsule itself.

 
A thin section showing two feet penetrating into the lens capsule. The capsule appears just under 10 microns thick in this micrograph though the apparent thickness will vary with the angle of section cut so the actual thickness may be less. Large numbers of small vesicles can also be seen
 
Single foot and higher magnification. Thin pale fibres can just be seen within the cytoplasm
 
Simplified 3D representation of a ligament filled structure on the eye lens capsule with associated cells and the many cell "feet"
 
Structure on outside surface of eye lens capsule at equator showing the fused cells and vesicles associated with it

The structures in the images are consistent with the laying down of new capsular material required for growth. Even though the capsule is a highly elastic structure,[14] it contains no elastic fibers. Elasticity is because of the thick lamellar arrangement of the collagen fibers.[10]

Function edit

The capsule helps give the lens its more spherical shape in aquatic vertebrates such as fish and more ellipsoidal shape in land based vertebrates such as sheep. In humans the lens ellipsoid becomes more flattened with age.[15] The capsule is the basement membrane for the epithelial cells at the front of the lens and the rapidly growing more flexible fiber cells of the back of the lens and below the epithelium at the front. Without the capsule substrate forming a tense support these cells lose their form as in the picture of a decapsulated sheep lens.

 
A sheep lens with the capsule stripped off. The classic lens shape is practically lost without the support of the capsule.

Accommodation edit

Main article: Accommodation (vertebrate eye)

Normally, when ciliary muscles are in a relaxed state, the zonules will pull the capsule. Due to this zonular tension anterior lens surface is flatter resulting in more distant objects being in focus. When ciliary muscles contract, the zonular tension will reduce allowing lens to assume more spherical shape. This shape change increases the focusing power of the eye allowing closer objects to come into focus. The process of changing the lens's focusing power to see closer objects more clearly is known as accommodation.

Embryology edit

 
Lens embryogenisis

The lens vesicle is developed from surface ectoderm.[16] It will separate from surface ectoderm at approximately day 33 in a human and only 3 days for a chicken. Lens capsule developed from basal lamina of lens vesicle will cover early lens fibers. Capsule is evident at 5 weeks of human gestation and begins its role in protecting and supporting the lens interior.[10]

Lens protection edit

Early embryologic development of lens capsule give lens material an immune privilege.[17] It will also help protect the lens from virus, bacteria and parasites.[18][10][19]

Vascular lens capsule edit

During fetal development vascular lens capsule (tunica vasculosa lentis) develops from the mesenchyme that surrounds the lens.[16] It receives arterial blood supply from the hyaloid artery.[8] This blood supply slowly regress and vascular capsule disappear before birth. The disappearance of the anterior vascular capsule of the lens is useful in estimating the gestational age.[20]

Clinical significance edit

In intra-capsular cataract extraction (ICCE), whole lens including the anterior part of the capsule is removed. During more common extra capsular cataract surgery procedures like micro incision cataract surgery, phacoemulsification etc., clouded lens is removed through opening made in anterior lens capsule.[21] The intraocular lens is then inserted into the lens capsule which is capable of rapid healing.[22] The best place for intraocular lens implantation is within the capsular bag.[23]

Posterior capsular opacification and posterior capsule rupture are common complications of cataract surgery.[24]

See also edit

References edit

  1. ^ "Mode of Discovering the Proper Capsule of the Crystalline Lens". The London Medical and Physical Journal. 34 (202): 453–454. December 1815. PMC 5594332. PMID 30493699.
  2. ^ 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. PMID 14283010.
  3. ^ Mohan, PS; Spiro, RG (25 March 1986). "Macromolecular organization of basement membranes. Characterization and comparison of glomerular basement membrane and lens capsule components by immunochemical and lectin affinity procedures". The Journal of Biological Chemistry. 261 (9): 4328–36. doi:10.1016/S0021-9258(17)35665-X. PMID 3512568.
  4. ^ Halfter, W; Candiello, J; Hu, H; Zhang, P; Schreiber, E; Balasubramani, M (January 2013). "Protein composition and biomechanical properties of in vivo-derived basement membranes". Cell Adhesion & Migration. 7 (1): 64–71. doi:10.4161/cam.22479. PMC 3544788. PMID 23154404.
  5. ^ a b Fisher, RF (March 1969). "Elastic constants of the human lens capsule". The Journal of Physiology. 201 (1): 1–19. doi:10.1113/jphysiol.1969.sp008739. PMC 1351628. PMID 5773553.
  6. ^ Yanoff, Myron. (2009). "Lens". Ocular pathology. Sassani, Joseph W. (6th ed.). Edinburgh: Mosby/Elsevier. ISBN 978-0-323-04232-1. OCLC 294998596.
  7. ^ Kastner, Christian; Löbler, Marian; Sternberg, Katrin; Reske, Thomas; Stachs, Oliver; Guthoff, Rudolf; Schmitz, Klaus-Peter (October 2013). "Permeability of the Anterior Lens Capsule for Large Molecules and Small Drugs". Current Eye Research. 38 (10): 1057–1063. doi:10.3109/02713683.2013.803288. PMID 23885713. S2CID 21090856.
  8. ^ a b Snell, Richard S. (2012). "Development of the Eye and the Ocular Appendages". Clinical anatomy of the eye. Lemp, Michael A. (2nd ed.). Malden, MA, USA: Blackwell Science. ISBN 978-0-632-04344-6. OCLC 37580703.
  9. ^ Salemann, M (1912). The Anatomy and Biology of the Human Eyeball in the Normal State. Chicago: University of Chicago Press. p. 165.
  10. ^ a b c d Clinical anatomy and physiology of the visual system (3rd ed.). Elsevier/Butterworth-Heinemann. 2012. ISBN 978-1-4377-1926-0.
  11. ^ Shi, Yanrong; Tu, Yidong; De Maria, Alicia; Mecham, Robert P.; Bassnett, Steven (1 April 2013). "Development, Composition, and Structural Arrangements of the Ciliary Zonule of the Mouse". Investigative Ophthalmology & Visual Science. 54 (4): 2504–2515. doi:10.1167/iovs.13-11619. PMC 3621578. PMID 23493297.
  12. ^ Bassnett, Steven (May 2021). "Zinn's zonule". Progress in Retinal and Eye Research. 82: 100902. doi:10.1016/j.preteyeres.2020.100902. PMC 8139560. PMID 32980533.
  13. ^ The eye : basic sciences in practice. London: W.B. Saunders. 1996. ISBN 0-7020-1790-6.
  14. ^ Bowman, W (1849). Lectures on the Parts Concerned in the Operations on the Eye and on the Structure of the Retina. Londan: Longmans.
  15. ^ "Lens Capsule". American Academy of Ophthalmology. 1 October 2019.
  16. ^ a b Young, P (January 1858). "On the Development of the Eye in the Chick". The British and Foreign Medico-chirurgical Review. 21 (41): 187–204. PMC 5186056. PMID 30164458.
  17. ^ Lang, RA (January 1997). "Apoptosis in mammalian eye development: lens morphogenesis, vascular regression and immune privilege". Cell Death and Differentiation. 4 (1): 12–20. doi:10.1038/sj.cdd.4400211. PMID 16465205. S2CID 10466397.
  18. ^ Karkinen-Jääskeläinen, M; Saxén, L; Vaheri, A; Leinikki, P (1 June 1975). "Rubella cataract in vitro: Sensitive period of the developing human lens". The Journal of Experimental Medicine. 141 (6): 1238–48. doi:10.1084/jem.141.6.1238. PMC 2189850. PMID 1092795.
  19. ^ Tham, MH; Hall, IB (July 1971). "Impacted microfilaria in the lens capsule". The British Journal of Ophthalmology. 55 (7): 484–6. doi:10.1136/bjo.55.7.484. PMC 1208424. PMID 5557527.
  20. ^ Hittner, H. M.; Hirsch, N. J.; Rudolph, A. J. (September 1977). "Assessment of gestational age by examination of the anterior vascular capsule of the lens". The Journal of Pediatrics. 91 (3): 455–458. doi:10.1016/s0022-3476(77)81324-3. ISSN 0022-3476. PMID 894419.
  21. ^ Fitzgerald, CE (22 November 1879). "Peripheral Division of the Capsule of the Lens". British Medical Journal. 2 (986): 811–2. doi:10.1136/bmj.2.986.811. PMC 2240914. PMID 20749364.
  22. ^ McDonnell, PJ; Patel, A; Green, WR (September 1985). "Comparison of intracapsular and extracapsular cataract surgery. Histopathologic study of eyes obtained postmortem". Ophthalmology. 92 (9): 1208–25. doi:10.1016/s0161-6420(85)33875-7. PMID 4058884.
  23. ^ Mehta, Rajvi; Aref, Ahmad A (27 November 2019). "Intraocular Lens Implantation In The Ciliary Sulcus: Challenges And Risks". Clinical Ophthalmology. 13: 2317–2323. doi:10.2147/OPTH.S205148. ISSN 1177-5467. PMC 6885568. PMID 31819356.
  24. ^ John F, Salmon (13 December 2019). Kanski's clinical ophthalmology : a systematic approach (9th ed.). Elsevier. ISBN 978-0-7020-7711-1.

December 15, 2023
capsule, lens, lens, capsule, component, globe, clear, elastic, basement, membrane, composed, collagen, laminin, quality, that, keeps, under, constant, tension, result, lens, naturally, tends, towards, rounder, more, globular, configuration, shape, must, assum. The lens capsule is a component of the globe of the eye 1 It is a clear elastic basement membrane composed of collagen IV 2 laminin etc 3 4 a quality that keeps it under constant tension 5 As a result 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 The lens capsule is the thickest basement membrane in the body 6 Capsule of lensThe upper half of a sagittal section through the front of the eyeball Capsule of lens labeled at center right DetailsIdentifiersLatincapsula lentisMeSHD007903TA98A15 2 05 007FMA58881Anatomical terminology edit on Wikidata Sheep eye lens capsule with ligaments lifting off lens showing fiber ends beneath Microscope image of lens capsule in relation to lens cell typesNormally the lens capsule serves as a diffusion barrier It is permeable to low molecular weight compounds 7 but restricts the movement of large colloidal particles 8 Contents 1 Anatomy 2 Function 2 1 Accommodation 3 Embryology 3 1 Lens protection 3 2 Vascular lens capsule 4 Clinical significance 5 See also 6 ReferencesAnatomy editThe lens capsule is a transparent membrane that surrounds the entire lens The capsule is thinnest at the posterior pole with approximate thickness of 3 5mm Average thickness at the equator is 7mm 5 9 Anterior pole thickness increases with age from 11 15mm The thickest portion of is annular region surrounding the anterior pole This will also increases with age from 13 5 16mm 10 The ligaments suspending the lens form attachments in the equatorial area and more so just to the front and back of the equator 11 There are tens of thousands of these ligaments in a mouse lens and for the most part they appear to connect directly to the lens capsule 12 nbsp Dissected equator of sheep eye lens showing capsule where ligaments attach nbsp Ligament connection to mouse capsule forming part of the Zonule of Zinn with associated cells and feet As the lens grows throughout the life of most vertebrates the capsule is required to grow as well 13 Some ligament anchors have associated cells where they connect to the lens capsule with periodic cellular processes penetrating the capsule itself nbsp A thin section showing two feet penetrating into the lens capsule The capsule appears just under 10 microns thick in this micrograph though the apparent thickness will vary with the angle of section cut so the actual thickness may be less Large numbers of small vesicles can also be seen nbsp Single foot and higher magnification Thin pale fibres can just be seen within the cytoplasm nbsp Simplified 3D representation of a ligament filled structure on the eye lens capsule with associated cells and the many cell feet nbsp Structure on outside surface of eye lens capsule at equator showing the fused cells and vesicles associated with itThe structures in the images are consistent with the laying down of new capsular material required for growth Even though the capsule is a highly elastic structure 14 it contains no elastic fibers Elasticity is because of the thick lamellar arrangement of the collagen fibers 10 Function editThe capsule helps give the lens its more spherical shape in aquatic vertebrates such as fish and more ellipsoidal shape in land based vertebrates such as sheep In humans the lens ellipsoid becomes more flattened with age 15 The capsule is the basement membrane for the epithelial cells at the front of the lens and the rapidly growing more flexible fiber cells of the back of the lens and below the epithelium at the front Without the capsule substrate forming a tense support these cells lose their form as in the picture of a decapsulated sheep lens nbsp A sheep lens with the capsule stripped off The classic lens shape is practically lost without the support of the capsule Accommodation edit Main article Accommodation vertebrate eye Normally when ciliary muscles are in a relaxed state the zonules will pull the capsule Due to this zonular tension anterior lens surface is flatter resulting in more distant objects being in focus When ciliary muscles contract the zonular tension will reduce allowing lens to assume more spherical shape This shape change increases the focusing power of the eye allowing closer objects to come into focus The process of changing the lens s focusing power to see closer objects more clearly is known as accommodation Embryology edit nbsp Lens embryogenisisThe lens vesicle is developed from surface ectoderm 16 It will separate from surface ectoderm at approximately day 33 in a human and only 3 days for a chicken Lens capsule developed from basal lamina of lens vesicle will cover early lens fibers Capsule is evident at 5 weeks of human gestation and begins its role in protecting and supporting the lens interior 10 Lens protection edit Early embryologic development of lens capsule give lens material an immune privilege 17 It will also help protect the lens from virus bacteria and parasites 18 10 19 Vascular lens capsule edit During fetal development vascular lens capsule tunica vasculosa lentis develops from the mesenchyme that surrounds the lens 16 It receives arterial blood supply from the hyaloid artery 8 This blood supply slowly regress and vascular capsule disappear before birth The disappearance of the anterior vascular capsule of the lens is useful in estimating the gestational age 20 Clinical significance editIn intra capsular cataract extraction ICCE whole lens including the anterior part of the capsule is removed During more common extra capsular cataract surgery procedures like micro incision cataract surgery phacoemulsification etc clouded lens is removed through opening made in anterior lens capsule 21 The intraocular lens is then inserted into the lens capsule which is capable of rapid healing 22 The best place for intraocular lens implantation is within the capsular bag 23 Posterior capsular opacification and posterior capsule rupture are common complications of cataract surgery 24 See also editLens anatomy References edit Mode of Discovering the Proper Capsule of the Crystalline Lens The London Medical and Physical Journal 34 202 453 454 December 1815 PMC 5594332 PMID 30493699 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 PMID 14283010 Mohan PS Spiro RG 25 March 1986 Macromolecular organization of basement membranes Characterization and comparison of glomerular basement membrane and lens capsule components by immunochemical and lectin affinity procedures The Journal of Biological Chemistry 261 9 4328 36 doi 10 1016 S0021 9258 17 35665 X PMID 3512568 Halfter W Candiello J Hu H Zhang P Schreiber E Balasubramani M January 2013 Protein composition and biomechanical properties of in vivo derived basement membranes Cell Adhesion amp Migration 7 1 64 71 doi 10 4161 cam 22479 PMC 3544788 PMID 23154404 a b Fisher RF March 1969 Elastic constants of the human lens capsule The Journal of Physiology 201 1 1 19 doi 10 1113 jphysiol 1969 sp008739 PMC 1351628 PMID 5773553 Yanoff Myron 2009 Lens Ocular pathology Sassani Joseph W 6th ed Edinburgh Mosby Elsevier ISBN 978 0 323 04232 1 OCLC 294998596 Kastner Christian Lobler Marian Sternberg Katrin Reske Thomas Stachs Oliver Guthoff Rudolf Schmitz Klaus Peter October 2013 Permeability of the Anterior Lens Capsule for Large Molecules and Small Drugs Current Eye Research 38 10 1057 1063 doi 10 3109 02713683 2013 803288 PMID 23885713 S2CID 21090856 a b Snell Richard S 2012 Development of the Eye and the Ocular Appendages Clinical anatomy of the eye Lemp Michael A 2nd ed Malden MA USA Blackwell Science ISBN 978 0 632 04344 6 OCLC 37580703 Salemann M 1912 The Anatomy and Biology of the Human Eyeball in the Normal State Chicago University of Chicago Press p 165 a b c d Clinical anatomy and physiology of the visual system 3rd ed Elsevier Butterworth Heinemann 2012 ISBN 978 1 4377 1926 0 Shi Yanrong Tu Yidong De Maria Alicia Mecham Robert P Bassnett Steven 1 April 2013 Development Composition and Structural Arrangements of the Ciliary Zonule of the Mouse Investigative Ophthalmology amp Visual Science 54 4 2504 2515 doi 10 1167 iovs 13 11619 PMC 3621578 PMID 23493297 Bassnett Steven May 2021 Zinn s zonule Progress in Retinal and Eye Research 82 100902 doi 10 1016 j preteyeres 2020 100902 PMC 8139560 PMID 32980533 The eye basic sciences in practice London W B Saunders 1996 ISBN 0 7020 1790 6 Bowman W 1849 Lectures on the Parts Concerned in the Operations on the Eye and on the Structure of the Retina Londan Longmans Lens Capsule American Academy of Ophthalmology 1 October 2019 a b Young P January 1858 On the Development of the Eye in the Chick The British and Foreign Medico chirurgical Review 21 41 187 204 PMC 5186056 PMID 30164458 Lang RA January 1997 Apoptosis in mammalian eye development lens morphogenesis vascular regression and immune privilege Cell Death and Differentiation 4 1 12 20 doi 10 1038 sj cdd 4400211 PMID 16465205 S2CID 10466397 Karkinen Jaaskelainen M Saxen L Vaheri A Leinikki P 1 June 1975 Rubella cataract in vitro Sensitive period of the developing human lens The Journal of Experimental Medicine 141 6 1238 48 doi 10 1084 jem 141 6 1238 PMC 2189850 PMID 1092795 Tham MH Hall IB July 1971 Impacted microfilaria in the lens capsule The British Journal of Ophthalmology 55 7 484 6 doi 10 1136 bjo 55 7 484 PMC 1208424 PMID 5557527 Hittner H M Hirsch N J Rudolph A J September 1977 Assessment of gestational age by examination of the anterior vascular capsule of the lens The Journal of Pediatrics 91 3 455 458 doi 10 1016 s0022 3476 77 81324 3 ISSN 0022 3476 PMID 894419 Fitzgerald CE 22 November 1879 Peripheral Division of the Capsule of the Lens British Medical Journal 2 986 811 2 doi 10 1136 bmj 2 986 811 PMC 2240914 PMID 20749364 McDonnell PJ Patel A Green WR September 1985 Comparison of intracapsular and extracapsular cataract surgery Histopathologic study of eyes obtained postmortem Ophthalmology 92 9 1208 25 doi 10 1016 s0161 6420 85 33875 7 PMID 4058884 Mehta Rajvi Aref Ahmad A 27 November 2019 Intraocular Lens Implantation In The Ciliary Sulcus Challenges And Risks Clinical Ophthalmology 13 2317 2323 doi 10 2147 OPTH S205148 ISSN 1177 5467 PMC 6885568 PMID 31819356 John F Salmon 13 December 2019 Kanski s clinical ophthalmology a systematic approach 9th ed Elsevier ISBN 978 0 7020 7711 1 Retrieved from https en wikipedia org w index php title Capsule of lens amp oldid 1177225701, wikipedia, wiki, book, books, library,

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