Lens Disorders

Abstract

The function of the crystalline lens of the eye is to focus light onto the retina. It has a unique structure, as lens cells are never shed but continually added throughout life. Cataract, or opacification, is by far the most common disorder affecting the lens.

Keywords: eye; lens; cataract; lenticonus; crystallin

Figure 1.

The adult lens consists of clinically discernible regions. (a) Lens viewed from anteroposterior. (b) Lens in cross‐section.

Figure 2.

Lens development. In humans, lens organogenesis begins in the fourth week of gestation with thickening of the surface ectoderm overlying the optic vesicle (a) to form the lens placode; (b) this area begins to invaginate (the lens pit) and (c) eventually closes over to form the lens vesicle; (d) cells lining the posterior wall of the lens vesicle rapidly elongate to form the primary lens fibers (embryonic nucleus); (e) thereafter, throughout life, secondary lens fibers differentiate from equatorial epithelial cells, forming concentric lamellae around the embryonic nucleus.

Figure 3.

Autosomal dominant congenital cataract phenotypes. (a) Slit‐lamp (above) and retroillumination (below) view of anterior polar cataract (47‐year‐old female). (b) Slit‐lamp and retroillumination view of a stationary posterior polar cataract (49‐year‐old female). (c) Slit‐lamp view of a progressive posterior polar cataract (9‐year‐old female). (d) Slit‐lamp and retroillumination view of a dense nuclear cataract (14‐year‐old male). (e) Slit‐lamp and retroillumination view of nuclear opacities (50‐year‐old female). (f) Slit‐lamp and retroillumination view of the Coppock‐like (pulverulent) cataract with fine nuclear opacities (24‐year‐old female). (g) Slit‐lamp and retroillumination view of the Coppock‐like cataract with dense central opacities (6‐year‐old female). (h) Slit‐lamp view of lamellar cataract. (i) Slit‐lamp view of a blue‐dot (cerulean) cataract (32‐year‐old male). (j) Slit‐lamp and retroillumination view of a cortical cataract (45‐year‐old female). (k) Slit‐lamp view of a fine pulverulent cataract (32‐year‐old male). (l) Slit‐lamp view of large pulverulent opacities (12‐year‐old female).

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References

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Elkington A and Frank H (1984) Clinical Optics. Oxford, UK: Blackwell.

Evans J, Rooney C, Ashwood F, Dattani N and Wormald R (1996) Blindness and partial sight in England and Wales: April 1990–March 1991. Health Trends 28: 5–12.

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McKusick V (1997) Online Mendelian Inheritance in Man, OMIM. Centre for Medical Genetics, John Hopkins University (Baltimore, MD) and National Centre for Biotechnology Information, National Library of Medicine (Bethesda, MD). 1998.

Pal J, Liu X, Mackay DA, et al. (2000) Connexin46 mutations linked to congenital cataract show loss of gap junction channel function. American Journal of Cell Physiology 279(3): C596–C602.

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Further Reading

Duke‐Elder S (1978) The Practice of Refraction Edinburgh, UK: Churchill Livingstone.

Ionides A, Francis PJ, Berry V, et al. (1999) Clinical and genetic heterogeneity in autosomal dominant congenital cataract. British Journal of Ophthalmology 83(7): 802–808.

Johnson GJ and Foster A (1998) Prevalence, incidence and distribution of visual impairment. The Epidemiology of Eye Disease, pp. 8–9. London, UK: Chapman & Hall.

Krutovskikh V and Yamasaki H (2000) Connexin gene mutations in human genetic diseases. Mutation Research 462(2–3): 197–207.

Lambert S (1997) Lens. Paediatric Ophthalmology. Oxford, UK: Blackwell Scientific.

Piatigorsky J (1998) Gene sharing in lens and cornea: facts and implications. Progress in Retina and Eye Research 17(2): 145–174.

Snell RS and Lemp MA (1989) Clinical Anatomy of the Eye, pp. 1–9. Oxford, UK: Blackwell Scientific.

Web Links

crystallin, αA (CRYAA); LocusID: 1409. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=1409

crystallin, βB2 (CRYBB2); LocusID: 1415. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=1415

crystallin, γC (CRYGC); LocusID: 1420. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=1420

gap junction protein, α8 (GJA8); LocusID: 2703. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=2703

lens intrinsic membrane protein 2 (LIM2); LocusID: 3982. LocusLink: http://www.ncbi.nlm.nih.gov/LocusLink/LocRpt.cgi?l=3982

crystallin, γC (CRYGC); MIM number: 123680. OMIM: http://www.ncbi.nlm.nih.gov/htbin‐post/Omim/dispmim?123680

crystallin, αA (CRYAA); MIM number: 123580. OMIM: http://www.ncbi.nlm.nih.gov/htbin‐post/Omim/dispmim?123580

crystallin, βB2 (CRYBB2); MIM number: 123620. OMIM: http://www.ncbi.nlm.nih.gov/htbin‐post/Omim/dispmim?123620

gap junction protein, α8 (GJA8); MIM number: 600897. OMIM: http://www.ncbi.nlm.nih.gov/htbin‐post/Omim/dispmim?600897

lens intrinsic membrane protein 2 (LIM2); MIM number: 154045. OMIM: http://www.ncbi.nlm.nih.gov/htbin‐post/Omim/dispmim?154045

Online Mendelian Inheritance in Man (OMIM). Database of human genes and genetic disorders made available online by the National Center for Biotechnology Information http://www.ncbi.nlm.nih.gov/Omim/

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How to Cite close
Francis, Peter(Jan 2006) Lens Disorders. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0006105]