| Cataract Classification and external resources |
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| 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 |
A cataract is a clouding that develops in the crystalline lens of the eye or in its envelope, varying in degree from slight to complete opacity and obstructing the passage of light. The lens is a transparent biconvex structure in the Eye that along with the Cornea, helps to Refract Light to be focused Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation especially visible Light. Early in the development of age-related cataract the power of the lens may be increased, causing near-sightedness (myopia), and the gradual yellowing and opacification of the lens may reduce the perception of blue colours. Myopia (from Greek: μυωπία myopia "near-sightedness" also called near- or short-sightedness, is a refractive defect Cataracts typically progress slowly to cause vision loss and are potentially blinding if untreated. Vision loss or visual loss is the absence of vision where it existed before which can happen either acutely (i Blindness is the condition of lacking Visual perception due to Physiological or Neurological factors [1]
A senile cataract, occurring in the aged, is characterized by an initial opacity in the lens, subsequent swelling of the lens and final shrinkage with complete loss of transparency. [2] Moreover, with time the cataract cortex liquefies to form a milky white fluid in a Morgagnian cataract, which can cause severe inflammation if the lens capsule ruptures and leaks. Untreated, the cataract can cause phacomorphic glaucoma. Glaucoma is a group of diseases of the Optic nerve involving loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. Very advanced cataracts with weak zonules are liable to dislocation anteriorly or posteriorly. The zonule of Zinn ( Zinn's membrane, ciliary zonule) is a ring of fibrous strands connecting the Ciliary body with the crystalline lens of the Such spontaneous posterior dislocations (akin to the historical surgical procedure of couching) in ancient times were regarded as a blessing from the heavens, because some perception of light was restored in the cataractous patients. 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 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"[3]). Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly 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"[4], so it is also possible that the name came about through the sense of "obstruction". A portcullis is a latticed Grille or Gate made of wood metal or a combination of the two Early Persian physicians called the term nazul-i-ah, or 'descent of the water' - vulgarised into waterfall disease or cataract - believing such blindness to be caused by an outpouring of corrupt humour into the eye. [5] In dialect English a cataract is called a pearl, as in "pearl eye" and "pearl-eyed". [6].
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Causes
Cataracts develop from a variety of reasons, including long-term ultraviolet exposure, exposure to radiation, secondary effects of diseases such as diabetes, hypertension and advanced age; they are usually a result of denaturation of lens proteins. Diabetes mellitus (ˌdaɪəˈbiːtiːz or /ˌdaɪəˈbiːtəs/ /məˈlaɪtəs/ or /ˈmɛlətəs/ often referred to simply as diabetes ( Ancient Greek: grc Denaturation is a process in which Proteins or Nucleic acids lose their structure (tertiary structure by application of some external stress or compound for Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl 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. Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is A congenital disorder is a disease or disorder that is present at birth Cataracts may also be produced by eye injury or physical trauma. Physical or Chemical injuries of the Eye can be a serious threat to vision if not treated appropriately and in a timely fashion Treatment of physical trauma is described here and in First aid. A study among Icelandair pilots showed commercial airline pilots as three times more likely to develop cataracts than people with non-flying jobs. Icelandair is the Flag carrier Airline of Iceland, based in Reykjavík. This is thought to be caused by excessive exposure to radiation coming from outer space. Outer space, often simply called space, comprises the relatively empty regions of the Universe outside the escape velocities of Celestial bodies. [7] Cataracts are also unusually common in persons exposed to infrared radiation, such as glassblowers who suffer from "exfoliation syndrome". Glassblowing is a glassforming technique that involves inflating the molten glass into a bubble or parison with the aid of the blowpipe or blow tube Exposure to microwave radiation can cause cataracts.
Cataracts may be partial or complete, stationary or progressive, hard or soft.
Some drugs can induce cataract development, such as Corticosteroids[8] and Ezetimibe and Seroquel. Corticosteroids are a class of Steroid hormones that are produced in the Adrenal cortex. Ezetimibe (ɛˈzɛtəmɪb is an anti-hyperlipidemic medication which is used to lower cholesterol levels Quetiapine ( kwe-TYE-a-peen marketed by AstraZeneca as Seroquel and by Orion Pharma as Ketipinor, is an Atypical antipsychotic
There are various types of cataract, e. g. nuclear, cortical, mature, hypermature. Cataracts are also classified by their location, e. g. posterior (classically due to steroid use[8][9]) and anterior (common (senile) cataract related to aging).
Epidemiology
Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people, according to the World Health Organization (WHO)[10]. In many countries surgical services are inadequate, and cataracts remain the leading cause of blindness. As populations age, the number of people with cataracts is growing. Cataracts are also an important cause of low vision in both developed and developing countries. Even where surgical services are available, low vision associated with cataracts may still be prevalent, as a result of long waits for operations and barriers to surgical uptake, such as cost, lack of information and transportation problems.
In the United States, age-related lenticular changes have been reported in 42% of those between the ages of 52 to 64[11], 60% of those between the ages 65 and 74[12], and 91% of those between the ages of 75 and 85[11].
Cataract surgery
When a cataract is "ripe" (sufficiently developed to be removed by surgery), the most effective and common treatment is to make an incision (capsulotomy) into the capsule of the cloudy lens in order to surgically remove the lens. 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 There are two types of eye surgery that can be used to remove cataracts: extra-capsular (extracapsular cataract extraction, or ECCE) and intra-capsular (intracapsular cataract extraction, or ICCE). Eye surgery, also known as orogolomistician surgery or ocular surgery, is Surgery performed on the Eye or its Adnexa, typically by
Extra-capsular (ECCE) surgery consists of removing the lens but leaving the majority of the lens capsule intact. The lens capsule is a component of the Eye. It is a clear membrane-like structure that is quite elastic a quality that keeps it under constant tension High frequency sound waves (phacoemulsification) are sometimes used to break up the lens before extraction. High frequency (HF radio frequencies are between 3 and 30 MHz. An acoustic wave is a weak compression wave (meaning a small pressure change that moves at the Speed of sound. Phacoemulsification refers to modern Cataract surgery in which the Eye 's 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. Plastic is the general common term for a wide range of synthetic or semisynthetic organic solid materials suitable for the manufacture of industrial products 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
Cataract operations are usually performed using a local anaesthetic and the patient is allowed to go home the same day. A local anesthetic is a drug that causes reversible Local anesthesia and a loss of Nociception. 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.
Complications after cataract surgery, including endophthalmitis, posterior capsular opacification and retinal detachment, are possible. Endophthalmitis is an inflammation of the internal coats of the Eye. 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.
Prevention
Although cataracts have no scientifically proven prevention, it is sometimes said that wearing ultraviolet-protecting sunglasses may slow the development of cataracts. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Sunglasses or sun glasses are a visual aid variously termed Spectacles or Glasses, which feature lenses that are coloured or darkened to prevent strong [13][14] Regular intake of antioxidants (such as vitamin A, C and E) is theoretically helpful, but taking them as a supplement has been shown to have no benefit. An antioxidant is a Molecule capable of slowing or preventing the oxidation of other molecules [15]
Recent research
Although statins are known for their ability to lower lipids, they are also believed to have antioxidant qualities. The statins (or HMG-CoA reductase inhibitors) form a class of hypolipidemic drugs used to lower Cholesterol levels in people with or at risk of Cardiovascular 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. [16]
Research is scant and mixed but weakly positive for the nutrients lutein and zeaxanthin[17][18][19][20]. Bilberry extract shows promise in rat models [21][22] and in clinical studies. [23]
Types of cataracts
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The following is a classification of the various types of cataracts. Congenital rubella syndrome (CRS can occur in a developing fetus of a pregnant woman who has contracted Rubella during her first trimester This is not comprehensive and other unusual types may be noted.
- Classified by etiology
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- Age-related cataract
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- 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
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- Sutural cataract
- Lamellar cataract
- Zonular cataract
- Total cataract
- Secondary cataract
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- Drug-induced cataract (e. The optic disc or optic nerve head is the location where Ganglion cell axons exit the Eye to form the Optic nerve. Zonular cataract and nystagmus, also referred as Nystagmus with congenital zonular cataract is a rare Congenital disease associated with Nystagmus The slit lamp is an instrument consisting of a high-intensity Light source that can be focused to shine as a slit g. Corticosteroids)
- Traumatic cataract
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- 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)
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- 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)
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- Anterior cortical cataract
- Anterior polar cataract
- Anterior subcapsular cataract
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- Nuclear cataract - Grading correlates with hardness & difficulty of surgical removal
- Posterior cortical cataract
- Posterior polar cataract (importance lies in higher risk of complication - posterior capsular tears during surgery)
- Posterior subcapsular cataract (PSC) (clinically common)
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- After-cataract - posterior capsular opacification subsequent to a successful extracapsular cataract surgery (usually within 3 months - 2 years) with or without IOL implantation. The slit lamp is an instrument consisting of a high-intensity Light source that can be focused to shine as a slit Hindi ( Devanāgarī: hi [[wiktहिन्दी हिन्दी]] or hi [[wiktहिंदी हिंदी]] IAST:, IPA:) is Glaucoma is a group of diseases of the Optic nerve involving loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. Requires a quick & painless office procedure with Nd:YAG laser capsulotomy to restore optical clarity. NdYAG ( neodymium-doped yttrium aluminium garnet; NdY3Al5O12) is a Crystal that is used as a lasing medium
Associations with systemic conditions
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- Alport's syndrome
- Cri-du-chat syndrome
- Conradi's syndrome
- Myotonic dystrophy
- Patau's syndrome
- Schmid-Fraccaro syndrome
- Trisomy 18 (Edward's syndrome)
- Turner's syndrome
- Disease of the skin and mucous membranes
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- Atopic dermatitis
- Basal-cell nevus syndrome
- Ichthyosis
- Pemphigus
- Metabolic and nutrition diseases
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- Congenital
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- Congential herpes simplex
- Congenital syphilis
- Cytomegalic inclusion disease
- Rubella
- Others
- Toxic substances introduced systemically
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- Corticosteroids
- Haloperidol
- Miotics
- Triparanol
References
- ^ Common Causes of Vision Loss in Elderly Patients - July 1999 - American Academy of Family Physicians
- ^ eMedicine - Cataract, Senile : Article by Vicente Victor D Ocampo. From eMedicine The Continually Updated Clinical Reference
- ^ Dictionary.com/Word of the Day Archive/cataract
- ^ Online Etymology Dictionary
- ^ Mistaken Science - Topic Powered by eve community. Wordcraft Forums
- ^ Webster's Revised Unabridged Dictionary (1913 edition). Public Reference Tools - The ARTFL Project (American and French Research on the Treasury of the French Laanguage), University of Chicago
- ^ Rafnsson, V; Olafsdottir E, Hrafnkelsson J, Sasaki H, Arnarsson A, Jonasson F. A genetic disorder is a condition caused by abnormalities in Genes or Chromosomes While some diseases such as Cancer, are due to genetic abnormalities acquired Alport syndrome is a Genetic disorder characterized by Glomerulonephritis, endstage kidney disease and hearing loss Cri du Chat syndrome or Cri-du-Chat syndrome (French for Cry or call of the cat referring to the specific cry of the child also called Conradi-Hünermann syndrome is a type of Chondrodysplasia punctata. Myotonic dystrophy (DM is a chronic, slowly progressing highly variable inherited multisystemic Disease that can manifest at any age from birth to old age Patau syndrome, also known as trisomy 13, is a chromosomal abnormality a Syndrome in which a patient has an additional chromosome 13 due Trisomy 18 or Edwards Syndrome is a Genetic disorder caused by the presence of all or part of an extra 18th chromosome. Trisomy 18 or Edwards Syndrome is a Genetic disorder caused by the presence of all or part of an extra 18th chromosome. Turner syndrome or Ullrich-Turner syndrome encompasses several conditions of which monosomy X is the most common The skin is the outer covering of living tissue of an animal (or plant The mucous membranes (or mucosae; singular mucosa) are linings of mostly endodermal origin covered in Epithelium, which are involved in Atopic dermatitis, also known as atopic eczema, is a disease characterized by Chronic inflammation of the skin which is atopic, hereditary and non-contagious Ichthyosis is a heterogeneous family of more than 30 generalized mostly genetic Skin disorders. Pemphigus (from the Greek pemphix: bubble or blister is an Autoimmune disease of the Skin and mucous membranes that causes vesicles Inborn errors of metabolism comprise a large class of genetic Diseases involving disorders of Metabolism. Aminoaciduria is the presence of Amino acids in the Urine. Small amounts of amino acids are also present in normal urine Oculocerebrorenal syndrome (also called Lowe syndrome) is a X-linked recessive disorder characterized by Hydrophthalmia, Cataracts Intellectual Diabetes mellitus (ˌdaɪəˈbiːtiːz or /ˌdaɪəˈbiːtəs/ /məˈlaɪtəs/ or /ˈmɛlətəs/ often referred to simply as diabetes ( Ancient Greek: grc Fabry disease (also known as Anderson-Fabry disease, Angiokeratoma corporis diffusum, Ruiter-Pompen-Wyers syndrome, Ceramide trihexosidosis Galactosemia is a rare genetic metabolic disorder which affects an individual's ability to properly metabolize the sugar Galactose. A Galactosemic cataract is Cataract which is associated with the consequences of Galactosemia. Homocystinuria, also known as Cystathionine beta synthase deficiency, is an inherited disorder of the Metabolism of the Amino acid Methionine Hypervitaminosis D is a state of Vitamin D toxicity The recommended daily allowance is 400 IU per day Hyperparathyroidism is overactivity of the Parathyroid glands resulting in excess production of Parathyroid hormone (PTH Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland. Mucopolysaccharidosis is a group of Autosomal recessive metabolic disorders caused by the absence or malfunctioning of lysosomal enzymes needed to break down Wilson's disease or hepatolenticular degeneration is an Autosomal recessive Genetic disorder in which Copper accumulates in tissues An infectious disease is a clinically evident Disease resulting from the presence of Pathogenic microbial agents including Pathogenic viruses Pathogenic Congenital syphilis is Syphilis present in utero and at birth and occurs when a child is born to a mother with secondary or tertiary syphilis Cytomegalovirus (CMV (from the Greek cyto-, "cell" and -megalo-, "large" is a viral Rubella, commonly known as German measles, is a Disease caused by Rubella virus Cysticercosis, or neurocysticercosis, is the most common parasitic Infestation of the Central nervous system worldwide Leprosy (from the Greek lepi (λέπι meaning scales on a fish or Hansen's disease, is a chronic disease caused by the bacterium Onchocerciasis ( or /ˈɒnkoʊsɝːˈkaɪəsɨs/ also known as river blindness, is the world's second leading infectious cause of Blindness. Toxoplasmosis is a Parasitic disease caused by the Protozoan Toxoplasma gondii. Corticosteroids are a class of Steroid hormones that are produced in the Adrenal cortex. Haloperidol is a Typical antipsychotic. It is in the Butyrophenone class of Antipsychotic medications and has pharmacological effects similar Miosis is Constriction of the Pupil of the Eye. This is a normal response to an increase in light but can also be associated with certain Pathological "Cosmic radiation increases the risk of nuclear cataract in airline pilots: a population-based case-control study". Arch Ophthalmol 123: 1102-1105.
- ^ 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.
- ^ Greiner J, Chylack L (1979). "Posterior subcapsular cataracts: histopathologic study of steroid-associated cataracts". Arch Ophthalmol 97 (1): 135-44. PMID 758890.
- ^ [http://www.who.int/blindness/causes/priority/en/index1.html WHO | Priority eye diseases. }
- ^ 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.
- ^ 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.
- ^ Epidemiology. 2003 Nov;14(6):707-12. Sun exposure as a risk factor for nuclear cataract
- ^ J.C. Javitt, F. Wang and S. K. West, “Blindness Due to Cataract: Epidemiology and Prevention.” Annual Review of Public Health 17 (1996): 159-77. Cited in Five-Year Agenda for the National Eye Health Education Program (NEHEP), p. B-2; National Eye Institute, U. S. National Institutes of Health
- ^ A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E and beta carotene for age-related cataract and vision loss: AREDS report no. 9. Arch Ophthalmol. 2001 Oct;119(10):1439-52
- ^ 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.
- ^ 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
- ^ Invest Ophthalmol Vis Sci. 2006 Sep;47(9):3783-6. Lutein and zeaxanthin and the risk of cataract: the Melbourne visual impairment project
- ^ 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
- ^ J Am Coll Nutr. 2004 Dec;23(6 Suppl):567S-587S Lutein and zeaxanthin and their potential roles in disease prevention
- ^ Dietary supplementation with bilberry extract prevents macular degeneration and cataracts in senesce-accelerated OXYS rats Adv Gerontol. 2005;16:76-9
- ^ Yamakoshi J, et al. J Agric Food Chem. 2002 Aug 14;50(17):4983-8.
- ^ Ann Ottalmol Clin Ocul, 1989
- Pavan-Langston, Deborah (1990). Manual of Ocular Diagnosis and Therapy. Little, Brown and Company.
See also
External links
- Cataract Resource Guide from the National Eye Institute (NEI). This is a partial list of human Eye diseases and disorders. The World Health Organization publishes a classification of known diseases and injuries called the This is a list of systemic diseases with ocular manifestations.
- eMedicine Health
- Video of Cataract Surgery
- The Childhood Cataract Network
Dictionary
cataract
-noun
- (obsolete) waterspout
- A large waterfall; steep rapids in a river.
- A downpour, flood of water
- (anatomy) An opacity of the lens in the eye. Usually manifests as a gradual yellowing of the lens which blures vision, eventually resulting in a total loss of transparency. Many types exist, mostly caused by age related degenerative changes, often occurring after 50 years of age.
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