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Encyclopedia > Cataract
Cataract
Classification & external resources
Magnified view of cataract in human eye, seen on examination with a slit lamp using diffuse illumination
ICD-10 H25.-H26., H28., Q12.0
ICD-9 366
DiseasesDB 2179
MedlinePlus 001001
Human eye cross-sectional view, showing position of human lens. Courtesy NIH National Eye Institute
Human eye cross-sectional view, showing position of human lens. Courtesy NIH National Eye Institute

A cataract is an opacity that develops in the crystalline lens of the eye or in its envelope. Early on in the development of age-related cataract the power of the crystalline lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colours. Cataracts typically progress slowly to cause vision loss and are potentially blinding if untreated.[1] Moreover, with time the cataract cortex liquefies to form a milky white fluid in a Morgagnian Cataract, and can cause severe inflammation if the lens capsule ruptures and leaks. Untreated, the cataract can cause phacomorphic glaucoma. Very advanced cataracts with weak zonules are liable to dislocation anteriorly or posteriorly. Such spontaneous posterior dislocations (akin to the historical surgical procedure of couching) in ancient times were regarded as a blessing from the heavens, because it restored some perception of light in the bilaterally affected patients. Image File history File links Download high resolution version (1543x1120, 1933 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cataract Lens (anatomy) Slit lamp Cataract surgery Anterior segment ... The slit-lamp examination looks at structures that are at the front of the eye (the anterior segment): The eyelid, the sclera (white outer structure of the eye), conjunctiva (membranes lining the eyelid and sclera surface), iris (colored part of the eye), natural crystalline lens, and the cornea (thin transparent... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // H00-H59 - Diseases of the eye and adnexa (H00-H06) Disorders of eyelid, lacrimal system and orbit (H00) Hordeolum and chalazion (H000) Hordeolum and other deep inflammation of eyelid (H001) Chalazion (H01) Other inflammation of eyelid (H010) Blepharitis (H011) Noninfectious dermatoses of eyelid (H02) Other disorders of eyelid (H020) Entropion... // H00-H59 - Diseases of the eye and adnexa (H00-H06) Disorders of eyelid, lacrimal system and orbit (H00) Hordeolum and chalazion (H000) Hordeolum and other deep inflammation of eyelid (H001) Chalazion (H01) Other inflammation of eyelid (H010) Blepharitis (H011) Noninfectious dermatoses of eyelid (H02) Other disorders of eyelid (H020) Entropion... // H00-H59 - Diseases of the eye and adnexa (H00-H06) Disorders of eyelid, lacrimal system and orbit (H00) Hordeolum and chalazion (H000) Hordeolum and other deep inflammation of eyelid (H001) Chalazion (H01) Other inflammation of eyelid (H010) Blepharitis (H011) Noninfectious dermatoses of eyelid (H02) Other disorders of eyelid (H020) Entropion... // Q00-Q99 - Congenital malformations, deformations and chromosomal abnormalities (Q00-Q07) Congenital malformations of the nervous system (Q00) Anencephaly and similar malformations (Q01) Encephalocele (Q02) Microcephaly (Q03) Congenital hydrocephalus (Q04) Other congenital malformations of brain (Q05) Spina bifida (Q06) Other congenital malformations of spinal cord (Q07) Other congenital malformations of nervous... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... MedlinePlus (medlineplus. ... Image File history File links Human_eye_cross-sectional_view_grayscale. ... Image File history File links Human_eye_cross-sectional_view_grayscale. ... National Institutes of Health Building 50 at NIH Clinical Center - Building 10 The National Institutes of Health (NIH) is an agency of the United States Department of Health and Human Services and is the primary agency of the United States government responsible for biomedical research. ... The National Eye Institute (NEI) is one of the US National Institutes of Health that was established in 1968. ... Image File history File links Eyesection. ... Image File history File links Eyesection. ... For other uses, see Eye (disambiguation). ... National Institutes of Health Building 50 at NIH Clinical Center - Building 10 The National Institutes of Health (NIH) is an agency of the United States Department of Health and Human Services and is the primary agency of the United States government responsible for biomedical research. ... The National Eye Institute (NEI) is one of the US National Institutes of Health that was established in 1968. ... Cataract may refer to: Cataract, an opacity in the lens of the eye Cataract, a European metalcore band from Switzerland signed to the Metal Blade Records a type of waterfall Cataract, a song by Sparta from their 2002 album Wiretap Scars Category: ... Look up opacity in Wiktionary, the free dictionary. ... Light from a single point of a distant object and light from a single point of a near object being brought to a focus by changing the curvature of the lens. ... For other uses, see Eye (disambiguation). ... Normal vision. ... Visual loss results in the absence of vision where it existed before, which can happen either acutely (i. ... This article is about the visual condition. ... Human eye cross-sectional view. ... The zonule of Zinn (Zinns membrane, ciliary zonule) is a ring of fibrous strands connecting the ciliary body with the crystalline lens of the eye. ... Cataract in Human Eye- Magnified view seen on examination with a slit lamp Cataract surgery is the removal of the lens of the eye (also called crystalline) that has developed an opacification, which is referred to as a cataract. ...


Cataract derives from the Latin cataracta meaning "waterfall" and the Greek kataraktes and katarrhaktes, from katarassein meaning "to dash down" (kata-, "down"; arassein, "to strike, dash"[2]). As rapidly running water turns white, the term may later have been used metaphorically to describe the similar appearance of mature ocular opacities. In Latin, cataracta had the alternate meaning, "portcullis"[3], so it is also possible that the name came about through the sense of "obstruction". For other uses, see Latin (disambiguation). ... Counterweights for the sliding portcullis A portcullis is a grille or gate made of wood, metal or a combination of the two. ...

Contents

Cataract Surgery Video

  • Video of Cataract Surgery

Causes

Cataracts develop from a variety of reasons, including long-term ultraviolet exposure, exposure to radiation, secondary effects of diseases such as diabetes, and advanced age; they are usually a result of denaturation of lens proteins. Genetic factors are often a cause of congenital cataracts and positive family history may also play a role in predisposing someone to cataracts at an earlier age, a phenomenon of "anticipation" in pre-senile cataracts. Cataracts may also be produced by eye injury or physical trauma. A study among Icelandair pilots showed commercial airline pilots as three times more likely to develop cataracts than people with non-flying jobs. This is thought to be caused by excessive exposure to radiation coming from outer space.[4] Cataracts are also unusually common in persons exposed to infrared radiation, such as glassblowers who suffer from "exfoliation syndrome". Exposure to microwave radiation can cause cataracts. This article is about the disease that features high blood sugar. ... Irreversible egg protein denaturation and loss of solubility, caused by the high temperature (while cooking it) Denaturation is the alteration of a protein or nucleic acids shape through some form of external stress (for example, by applying heat, acid or alkali), in such a way that it will no... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... This article is about the general scientific term. ... A congenital disorder is a medical condition or defect that is present at or before birth (for example, congenital heart disease). ... Physical or chemical injuries of the eye can be a serious threat to vision if not treated appropriately and in a timely fashion. ... In medicine, a trauma patient has suffered serious and life-threatening physical injury resulting in secondary complications such as shock, respiratory failure and death. ... Icelandair (OMX: ICEAIR ) is the flag carrier airline of Iceland, based in Reykjavík. ... Layers of Atmosphere - not to scale (NOAA)[1] Outer space, sometimes simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. ... Sculpting hot blown glass. ...


Cataracts may be partial or complete, stationary or progressive, hard or soft.


Some drugs can induce cataract development, such as Corticosteroids[5] and Ezetimibe[citation needed] In physiology, corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. ... Ezetimibe (IPA: ) is an anti-hyperlipidemic medication which is used to lower cholesterol levels. ...


There are various types of cataracts, e.g. nuclear, cortical, mature, hypermature. Cataracts are also classified by their location, e.g. posterior (classically due to steroid use[5][6]) and anterior (common (senile) cataract related to aging).


Epidemiology

Cataracts are the leading cause of blindness in the world.[7]


In the United States, age-related lenticular changes have been reported in 42% of those between the ages of 52 to 64[8], 60% of those between the ages 65 and 74[9], and 91% of those between the ages of 75 and 85[8].


Cataract surgery

Main article: Cataract surgery
Cataract surgery, using a temporal approach phacoemulsification probe (in right hand) and "chopper" (in left hand) being done under operating microscope at a Navy medical center

The most effective and common treatment is to surgically remove the cloudy lens. There are two types of surgery that can be used to remove cataracts: extra-capsular (extracapsular cataract extraction, or ECCE) and intra-capsular (intracapsular cataract extraction, or ICCE). Cataract surgery is the removal of the lens of the eye that has developed a cataract. ... Image File history File linksMetadata Download high-resolution version (2100x1576, 480 KB) source: http://www. ... Image File history File linksMetadata Download high-resolution version (2100x1576, 480 KB) source: http://www. ... “Surgeon” redirects here. ...


Extra-capsular (ECCE) surgery consists of removing the lens but leaving the majority of the lens capsule intact. High frequency sound waves (phacoemulsification) are sometimes used to break up the lens before extraction. The lens capsule is a component of the eye. ... High frequency (HF) radio frequencies are between 3 and 30 MHz. ... This article is about compression waves. ... Phacoemulsification: Cataract surgery, by a temporal approach, using a phacoemulsification probe (in right hand) and chopper(in left hand), being done under operating microscope at a Navy medical center Phacoemulsification refers to modern cataract surgery in which the eyes internal lens is emulsified with an ultrasonic handpiece, and aspirated...


Intra-capsular (ICCE) surgery involves removing the entire lens of the eye, including the lens capsule, but it is rarely performed in modern practice. In either extra-capsular surgery or intra-capsular surgery, the cataractous lens is removed and replaced with a plastic lens (an intraocular lens implant) which stays in the eye permanently. For other uses, see Plastic (disambiguation). ... An intraocular lens (IOL) is an implanted lens in the eye, usually replacing the existing crystalline lens because it has been clouded over by a cataract, or as a form of refractive surgery to change the eyes optical power. ...


Cataract operations are usually performed using a local anaesthetic and the patient is allowed to go home the same day. Recent improvements in intraocular technology now allow cataract patients to choose a multifocal lens to create a visual environment in which they are less dependent on glasses. Under some medical systems multifocal lenses cost extra. Traditional intraocular lenses are monofocal. A local anesthetic is a drug that reversibly inhibits the propagation of signals along nerves. ...


Complications after cataract surgery, including endophthalmitis, posterior capsular opacification and retinal detachment, are possible. Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. ...


In ICCE there is the issue of the Jack in the box phenomenon where the patient has to wear aphakic glasses - alternatives include contact lenses but these can prove to be high maintenance, particularly in dusty areas. Aphakia is the absence of the lens of the eye, due to surgical removal, a perforating wound or ulcer, or congenital anomaly. ...


Prevention

Although cataracts have no scientifically proven prevention, it is sometimes said that wearing ultraviolet-protecting sunglasses may slow the development of cataracts.[10][11] Regular intake of antioxidants (such as vitamin C and E) is theoretically helpful, but this has not been proven. For other uses, see Ultraviolet (disambiguation). ... Ray-Ban Wayfarer sunglasses (RB2132 901L) Sunglasses or sun glasses are a visual aid, variously termed spectacles or glasses, which feature lenses that are coloured or darkened to prevent strong light from reaching the eyes. ... An antioxidant is a chemical that prevents the oxidation of other chemicals. ...


Recent research

Although statins are known for their ability to lower lipids, they are also believed to have antioxidant qualities. It is believed that oxidative stress plays a role in the development of nuclear cataracts, which are the most common type of age-related cataract. To explore the relationship between nuclear cataracts and statin use, a group of researchers took a group of 1299 patients who were at risk of developing nuclear cataracts and gave some of them statins. Their results suggest that statin use in a general population may be associated with a lower risk of developing nuclear cataract disease. [12] Lovastatin, the first statin to be marketed The statins form a class of hypolipidemic agents. ...


Research is scant and mixed but weakly positive for the nutrients lutein and zeaxanthin[13][14][15][16]. Bilberry extract shows promise in rat models [17][18] and in clinical studies.[19]


Types of cataracts

Bilateral cataracts in an infant due to Congenital rubella syndrome, courtesy CDC

The following is a classification of the various types of cataracts. This is not comprehensive and other unusual types may be noted. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Congenital rubella syndrome (CRS) can occur in a developing fetus of a pregnant woman who has contracted rubella during her first trimester. ...

  • Classified by etiology
  • Age-related cataract
  • Immature Senile Cataract (IMSC) - partially opaque lens, disc view hazy
  • Mature Senile Cataract (MSC) - Completely opaque lens, no disc view
  • Hypermature Senile Cataract (HMSC) - Liquefied cortical matter: Morgagnian Cataract
  • Congenital cataract
  • Sutural cataract
  • Lamellar cataract
  • Zonular cataract
  • Total cataract
  • Secondary cataract
Slit lamp photo of Anterior capsular opacification visible a few months after implantation of Intraocular lens in eye, magnified view
  • Drug-induced cataract (e.g. Corticosteroids)
  • Traumatic cataract
  • Blunt trauma (capsule usually intact)
  • Penetrating trauma (capsular rupture & leakage of lens material - calls for an emergency surgery for extraction of lens and leaked material to minimize further damage)
  • Classified by location of opacity within lens structure (However, mixed morphology is quite commonly seen, e.g. PSC with nuclear changes & cortical spokes of cataract)
  • Anterior cortical cataract
  • Anterior polar cataract
  • Anterior subcapsular cataract
Slit lamp photo of Posterior capsular opacification visible a few months after implantation of Intraocular lens in eye, seen on retroillumination
  • Nuclear cataract - Grading correlates with hardness & difficulty of surgical removal
  • 1 - Grey
  • 2 - Yellow
  • 3 - Amber
  • 4 - Brown/Black (Note: "Black cataract" translated in some languages (like Hindi) refers to Glaucoma, not the color of the lens nucleus)
  • Posterior cortical cataract
  • Posterior polar cataract (importance lies in higher risk of complication - posterior capsular tears during surgery)
  • Posterior subcapsular cataract (PSC) (clinically common)
  • After-cataract - posterior capsular opacification subsequent to a successful extracapsular cataract surgery (usually within 3 months - 2 years) with or without IOL implantation. Requires a quick & painless office procedure with Nd:YAG laser capsulotomy to restore optical clarity.

The optic disc or optic nerve head is the location where ganglion cell axons exit the eye to form the optic nerve. ... Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... The slit-lamp examination looks at structures that are at the front of the eye (the anterior segment): The eyelid, the sclera (white outer structure of the eye), conjunctiva (membranes lining the eyelid and sclera surface), iris (colored part of the eye), natural crystalline lens, and the cornea (thin transparent... Image File history File linksMetadata Posterior_capsular_opacification_on_retroillumination. ... Image File history File linksMetadata Posterior_capsular_opacification_on_retroillumination. ... The slit-lamp examination looks at structures that are at the front of the eye (the anterior segment): The eyelid, the sclera (white outer structure of the eye), conjunctiva (membranes lining the eyelid and sclera surface), iris (colored part of the eye), natural crystalline lens, and the cornea (thin transparent... Hindi (DevanāgarÄ«: or , IAST: , IPA:  ), an Indo-European language spoken all over India in varying degrees and extensively in northern and central India, is one of the 22 official languages of India and is also used for central government administrative purposes , along with English. ...

Associations with systemic conditions

  • Congenital
  • Others
  • Toxic substances introduced systemically

A genetic disorder, or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. ... Alport syndrome is a genetic condition characterized by the progressive loss of kidney function and hearing. ... 5p- karyotype Cri du chat syndrome, also called deletion 5p syndrome, or 5p minus, is a rare genetic disorder due to a missing portion of chromosome 5. ... Patau syndrome, also known as Trisomy 13, is a chromosomal aberration, a disease in which a patient has an additional chromosome 13. ... Edwards Syndrome is the second most common trisomy after Downs Syndrome. ... Trisomy 18 or Edwards Syndrome (named after John H. Edwards) is a genetic disorder. ... Beyond overall skin structure, refer below to: See-also. ... The mucous membranes (or mucosa) are linings of ectodermic origin, covered in epithelium, that line various body cavities and internal organs. ... Ichthyosis is a family of dermatological conditions seen in man and domestic animals. ... Pemphigus is an autoimmune disorder that causes blistering and raw sores on skin and mucous membranes. ... A metabolic disease is a disease caused by malfunction in the human total metabolism. ... Aminoaciduria is the presence of amino acids in the urine. ... Oculocerebrorenal syndrome (also called Lowe syndrome) is a X-linked recessive disorder characterized by hydrophthalmia, cataracts, mental retardation, aminoaciduria, reduced renal ammonia production and vitamin D-resistant rickets. ... For the disease characterized by excretion of large amounts of very dilute urine, see diabetes insipidus. ... Fabry disease (also known as Anderson-Fabry disease, Angiokeratoma corporis diffusum, Ceramide trihexosidosis, and Sweeley-Klionsky disease) is an X-linked recessive inherited lysosomal storage disease. ... Galactosemia is a rare genetic metabolic disorder which affects an individuals ability to properly digest the sugar galactose. ... Homocystinuria, also known as Cystathionine beta synthase deficiency, is inherited disorder of the metabolism of the amino acid methionine. ... Hypervitaminosis D is a state of Vitamin D toxicity. ... Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone (PTH). ... This article or section does not cite its references or sources. ... The mucopolysaccharidoses are inborn errors of metabolism resulting from the deficiency of specific lysosomal enzymes needed in glycosaminoglycan catabolism. ... Wilsons disease or hepatolenticular degeneration is an autosomal recessive hereditary disease, with an incidence of about 1 in 30,000 in most parts of the world and a male preponderance. ... This false-colored electron micrograph shows a malaria sporozoite migrating through the midgut epithelia. ... A disease caused by infection with cytomegalovirus, characterized by the presence of inclusion bodies in infected cells, enlargement of the liver and spleen, jaundice, purpura, thrombocytopenia, and fever; it often occurs in newborn infants, acquired in the womb or when passing through the birth canal of an infected mother, and... Rubella, commonly known as German measles, is a disease caused by the rubella virus. ... Cysticercosis, or neurocysticercosis, is the most common parasitic infection of the central nervous system worldwide. ... For the malady found in the Hebrew Bible, see the article Tzaraath. ... Binomial name Onchocerca volvulus Bickel 1982 Onchocerciasis (pronounced ) or river blindness is the worlds second leading infectious cause of blindness. ... In physiology, corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. ... Haloperidol (sold under the tradenames Aloperidin, Bioperidolo, Brotopon, Dozic, Duraperidol (Germany), Einalon S, Eukystol, Haldol, Halosten, Keselan, Linton, Peluces, Serenace, Serenase, Sigaperidol) is a conventional, or typical, butyrophenone antipsychotic drug. ... A miotic substance causes the constriction of the pupil of the eye (or miosis). ...

References

  1. ^ http://www.aafp.org/afp/990700ap/99.html
  2. ^ http://dictionary.reference.com/wordoftheday/archive/2003/10/29.html]
  3. ^ http://www.etymonline.com/index.php?term=cataract
  4. ^ Rafnsson, V; Olafsdottir E, Hrafnkelsson J, Sasaki H, Arnarsson A, Jonasson F. "Cosmic radiation increases the risk of nuclear cataract in airline pilots: a population-based case-control study". Arch Ophthalmol 123: 1102-1105. 
  5. ^ a b SPENCER R, ANDELMAN S. "STEROIDSAREBAD CATARACTS. POSTERIOR SUBCAPSULAR CATARACT FORMATION IN RHEUMATOID ARTHRITIS PATIENTS ON LONG TERM STEROID THERAPY". Arch Ophthalmol 74: 38-41. PMID 14303339. 
  6. ^ Greiner J, Chylack L (1979). "Posterior subcapsular cataracts: histopathologic study of steroid-associated cataracts". Arch Ophthalmol 97 (1): 135-44. PMID 758890. 
  7. ^ https://web.emmes.com/study/areds/mopfiles/chp2_mop.pdf
  8. ^ a b Sperduto RD, Seigel D. Sperduto RD, Seigel D. "Senile lens and senile macular changes in a population-based sample." Am J Ophthalmol. 1980 Jul;90(1):86-91. PMID 7395962.
  9. ^ Kahn HA, Leibowitz HM, Ganley JP, Kini MM, Colton T, Nickerson RS, Dawber TR. "The Framingham Eye Study. I. Outline and major prevalence findings." Am J Epidemiol. 1977 Jul;106(1):17-32. PMID 879158.
  10. ^ Epidemiology. 2003 Nov;14(6):707-12. Sun exposure as a risk factor for nuclear cataract
  11. ^ http://www.nei.nih.gov/nehep/pdf/NEHEP_5_year_agenda_2006.pdf p.37 quoting Javitt, J. C., F. Wang, and S. K. West. “Blindness Due to Cataract: Epidemiology and Prevention.” Annual Review of Public Health 17 (1996): 159-77.
  12. ^ Klein, Barbara; Ronald Klein, Kristine Lee, and Lisa Grady. "Statin Use and Incident Nuclear Cataract". Journal of the American Medical Association 295 (23): 2752-2758. 
  13. ^ Nutrition. 2003 Jan;19(1):21 Lutein, but not alpha-tocopherol, supplementation improves visual function in patients with age-related cataracts: a 2-y double-blind, placebo-controlled pilot study
  14. ^ Invest Ophthalmol Vis Sci. 2006 Sep;47(9):3783-6. Lutein and zeaxanthin and the risk of cataract: the Melbourne visual impairment project
  15. ^ Invest Ophthalmol Vis Sci. 2006 Jun;47(6):2329-35. Plasma lutein and zeaxanthin and other carotenoids as modifiable risk factors for age-related maculopathy and cataract: the POLA Study
  16. ^ J Am Coll Nutr. 2004 Dec;23(6 Suppl):567S-587S Lutein and zeaxanthin and their potential roles in disease prevention
  17. ^ Dietary supplementation with bilberry extract prevents macular degeneration and cataracts in senesce-accelerated OXYS rats Adv Gerontol. 2005;16:76-9
  18. ^ Yamakoshi J, et al. J Agric Food Chem. 2002 Aug 14;50(17):4983-8.
  19. ^ Ann Ottalmol Clin Ocul, 1989
  • Pavan-Langston, Deborah (1990). Manual of Ocular Diagnosis and Therapy. Little, Brown and Company.

See also

This is a partial list of human eye diseases and disorders. ... This is a list of systemic diseases with ocular manifestations. ...

External links

  • Cataract Resource Guide from the National Eye Institute (NEI).
  • eMedicine Health

  Results from FactBites:
 
Cataract - Wikipedia, the free encyclopedia (1249 words)
Cataracts form for a variety of reasons, including long-term ultraviolet exposure, secondary effects of diseases such as diabetes, or simply due to advanced age; they are usually a result of denaturation of lens proteins.
Genetic factors are often a cause of congenital cataracts and positive family history may also play a role in predisposing someone to cataracts at an earlier age, a phenomenon of "anticipation" in pre-senile cataracts.
In either extra-capsular surgery or intra-capsular surgery, the cataractous lens is removed and replaced with a plastic lens (an intraocular lens implant) which remains permanently in the eye.
Cataract (526 words)
A cataract is a cloudy or opaque area in the lens of the eye.
Cataracts are accelerated by environmental factors, such as smoking or exposure to other toxic substances, or they may develop at any time after an eye injury.
Congenital cataracts can also be caused by infections of the mother during pregnancy such as rubella, or associated with metabolic disorders such as galactosemia.
  More results at FactBites »

 
 

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