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opacity of the lens of the eye or its capsule. adj., adj catarac´tous.
Causes and Symptoms. Some cataracts result from injuries to the eye, exposure to great heat or radiation, or inherited factors. The great majority, however, are “senile” cataracts, which are apparently a part of the aging process of the human body.

Blurred and dimmed vision are often the first symptoms. The patient may find that a brighter reading light is needed, or objects must be held closer to the eyes for better vision. Continued clouding of the lens may cause double vision; eventually there may be a need for frequent changes of eyeglasses. These symptoms do not necessarily indicate cataract, but if any of them are present, an ophthalmologist should be consulted immediately.
Treatment. The only known effective treatment for cataract is surgical removal of the lens (lens extraction or cataract extraction). The procedure of choice was formerly intracapsular extraction, with total removal of the lens within its capsule. This may be done by forceps or by cryoextraction using a supercooled metal probe that forms a bond with the lens capsule. The inner portion of the lens can be removed by emulsification and aspiration. More recently the removed cataract has been replaced with a plastic intraocular lens. In this procedure the inner portions of the lens (the nucleus and cortex) may be all that is removed; the capsule is retained and the intraocular lens is placed inside it.

The lens of the eye serves only to focus light rays upon the retina. After cataract extraction the loss of the natural lens is compensated for by either special eyeglasses or contact lenses. Implantation of a permanent artificial lens, either during cataract surgery or later, is an alternative to use of cataract spectacles and a removable contact lens.
Patient Care. Eye drops are administered to produce mydriasis and vasoconstriction. Because these patients may have extremely poor eyesight, care should be taken that they do not injure themselves. (See also vision.) Local anesthesia is usually preferred for the surgical procedure and preoperative medications are given to produce drowsiness. Ambulatory care surgery with same-day admission and discharge is becoming increasingly routine. Careful observation of the patient on follow-up visits is important. One needs to be on the alert for a complaint of pain in the eye followed by nausea and vomiting. These could be signs that the patient has increased intraocular pressure within the operative eye and measures need to be taken to reduce the pressure.
after-cataract any membrane of the pupillary area after extraction or absorption of the lens. See also secondary cataract.
atopic cataract cataract occurring, most often in the second to third decade, in those with longstanding atopic dermatitis.
brown cataract (brunescent cataract) senile cataract appearing as a brown opacity.
capsular cataract one consisting of an opacity of the capsule of the lens.
complicated cataract secondary cataract.
cortical cataract an opacity in the cortex of the lens.
hypermature cataract one in which the entire lens capsule is wrinkled and the contents have become solid and shrunken, or soft and liquid.
immature cataract (incipient cataract) an incomplete cataract; the lens is only slightly opaque and the cortex clear.
intumescent cataract a mature cataract that progresses; the lens becomes swollen from the osmotic effect of degenerated lens protein, and this may lead to secondary angle closure (acute) glaucoma.
lenticular cataract opacity of the lens not affecting the capsule.
mature cataract a cataract that produces swelling and opacity of the entire lens; cataracts are removed before maturity.
presenile cataract a subcapsular senile cataract in a person under 40 years of age.
secondary cataract a cataract, usually posterior subcapsular, that arises from either disease (especially iridocyclitis), degeneration (such as chronic glaucoma or retinal detachment), or surgery (such as glaucoma filtering or retinal reattachment).
senile cataract cataract with no obvious cause occurring in persons over 50 years old.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(kat'ă-rakt), Avoid the redundant phrase ocular cataract.
Complete or partial opacity of the ocular lens.
Synonym(s): cataracta
[L. cataracta, fr. G. katarrhaktēs, a downrushing, a waterfall, fr. katarrhēgnymi, to break down, rush down]
Farlex Partner Medical Dictionary © Farlex 2012


1. A large or high waterfall.
2. A great downpour; a deluge.
3. Medicine Opacity of the lens or capsule of the eye, causing impairment of vision or blindness.

cat′a·rac′tous (-răk′təs) adj.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Lens opacity Ophthalmology Partial or complete opacification of the ocular lens or capsule, which impairs vision or causes blindness Classification Morphology–size, shape, location; etiology–eg DM, corticosteroids, trauma, und so weiter; time of occurrence–eg in elderly Clinical Double or blurred vision; ↑ sensitivity to light, glare Diagnosis Slit lamp microscopy Treatment Phacoemulsion, surgery. See Black cataract, Congenital cataract, Snowflake cataract, Sunflower cataract.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


Complete or partial opacity of the ocular lens.
[L. cataracta fr. G. katarrhaktes a downrushing, a waterfall, fr. katarrhēgnymi, to break down, rush down]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


(kat'a-rakt?) [L. catar(r)acta, fr Gr. katarraktes, waterfall]
Enlarge picture
CATARACT: (Courtesy of Christine Chung, MD)
An opacity of the lens of the eye, usually occurring as a result of aging, trauma, endocrine or metabolic disease, intraocular disease, or as a side effect of the use of tobacco or certain medications, e.g., steroids. Cataracts are the most common cause of blindness in adults. See: illustration; visual field for illus.


At first, vision is distorted, particularly during night driving or in very bright light, causing light sensitivity (photophobia). As the cataract progresses, severe visual impairment develops.


Ninety percent of adults over 65 have cataracts.


Removal of the lens is the only effective treatment. In the U.S. about a million cataract surgeries are performed annually, usually as an outpatient, same-day procedure. Typically, the lens and its anterior capsule are removed by extracapsular extraction or by phacoemulsification, leaving the posterior capsule of the lens in place, and a posterior chamber intraocular lens is inserted where the patient’s own lens used to be. See: extracapsular extraction; intraocular lens; phacoemulsification

Patient care

Preoperative: The procedure is explained to the patient. An antiseptic facial scrub is performed. Mydriatic and cycloplegic eye drops are instilled to dilate the pupil, followed by lidocaine jelly and betadine drops prior to surgery; osmotic diuretics may be given to reduce intraocular pressure. An intravenous access is initiated, and antibiotics, a sedative, short-acting general anesthetic, and a local anesthetic are provided.

Postoperative: The patient is instructed to wear a clear eyeshield if prescribed, and to call if experiencing pain, or loss of vision. Blurred vision the day of surgery is to be expected. Eye drops are to be placed as directed and the patient should not swim or strain himself. A postoperative checkup visit is scheduled for the day following surgery. Both patient and family are taught how to inspect the eye for redness or watering and to report these conditions as well as any photophobia or sudden visual changes; wash hands well and then to instill eye drops (antibiotic to prevent inflammation and steroids to reduce infection) as prescribed; and to maintain the eye patch and shield as prescribed by the surgeon. The patient should be taught to protect the eye from bright sunlight or glare by wearing dark glasses. The patient should not swim or strain himself or herself.

capsular cataract

A cataract occurring in the capsule of the ocular lens.

cortical cataract

A cataract that develops in the cortex of the lens. It has a spiky or spoked appearance on physical examination of the eye.

hypermature cataract

A cataract in which the lens solidifies and shrinks. This stage follows the mature stage.

immature cataract

An early cataract, too poorly developed to require therapy.

lenticular cataract

A cataract occurring in the lens.

mature cataract

Sufficiently dense changes in the anterior cortex of the lens to prevent the examiner from viewing the posterior portion of the lens and the posterior portion of the eye; that is, the entire lens is opaque and ophthalmoscopic examination of the eye past the lens is not possible.

morgagnian cataract

See: Morgagni cataract

nuclear cataract

, nuclear sclerotic c.
A cataract in which the central portion of the lens is opacified.

posterior cortical cataract

Posterior subcapsular cataract.

posterior subcortical cataract

Posterior subcapsular cataract.

posterior subcapsular cataract

Abbreviation: PSC
A cataract between the posterior capsule and cortex. It is more common in younger patients, diabetics, and patients who use steroids. It tends to diminish near vision before it affects distance vision.
Synonym: posterior subcortical cataract; posterior cortical cataract

radiation cataract

A cataract caused by exposure to radiation, esp. from sunlight.

senile cataract

A cataract occurring in an older person.

zonular cataract

A cataract with opacity limited to certain layers of the lens.
Medical Dictionary, © 2009 Farlex and Partners


Opacification of the internal focusing lens of the eye (the crystalline lens) due to changes in hydration and denaturation of protein causing irreversible structural changes in the orderly arrangement of the fibres from which the lens is made. There may also be aggregation of crystallin protein in the lens. These changes may be CONGENITAL, the result of trauma, or, most commonly, an apparently spontaneous age-related effect. Some experts believe that age-related cataract is caused by ultraviolet radiation in sunlight but others disagree.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


Progressive opacity or clouding of an eye lens, which obstructs the passage of light to the retina.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


Partial or complete loss of transparency of the crystalline lens substance or its capsule. Cataract may occur as a result of age, trauma, systemic diseases (e.g. diabetes), ocular diseases (e.g. anterior uveitis), high myopia, long-term steroid therapy, excessive exposure to infrared and ultraviolet light, heredity, maternal infections, Down's syndrome, etc. The incidence of cataract increases with age, amounting to more than 50% in the population over 82 years. It is also more prevalent in Africa, Asia and South America than in Europe and North America. The main symptom is a gradual loss of vision, often described as 'misty'. Some patients may also notice transient monocular diplopia, others fixed spots (not floaters) in the visual field and others better vision in dim illumination. Cataracts can easily be seen with the retinoscope, the ophthalmoscope and especially with the slit-lamp, although depending on the type, one instrument may be better than the other. At present the main treatment is surgical. Extraction is performed for one of three reasons: visual improvement, medical or cosmetic. See after-cataract; juvenile idiopathic arthritis; biometry of the eye; crystalline lens capsule; Wilson's disease; blue field entoptoscope; glare tester; hyperacuity; crystalline lens; intraocular lens; leukocoria; clinical maxwellian view system; lenticular myopia; phacoemulsification; Down's syndrome; persistent hyperplastic primary vitreous.
age-related cataract Cataract affecting older persons. It is the most common type of cataract and may take several forms: cortical, cuneiform, nuclear, mature or subcapsular. Syn. senile cataract.
anterior capsular cataract A small central opacity located on the anterior lens capsule, either of congenital origin or due to a perforating ulcer of the cornea. See Vogt's sign.
axial cataract An opacity situated along the anteroposterior axis of the crystalline lens (Fig. C3).
bipolar cataract An opacity involving both the anterior and the posterior poles of the lens (Fig. C3). See polar cataract.
blue cataract See blue-dot cataract.
blue-dot cataract A developmental anomaly of the crystalline lens characterized by numerous small opacities in the outer nucleus and cortex, which appear as translucent bluish dots. The condition is very common and does not usually affect acuity. Syn. blue cataract; diffuse cataract; punctate cataract.
brown; brunescent cataract See nuclear cataract.
capsular cataract An opacity confined only to the capsule of the crystalline lens, anteriorly or posteriorly. It is usually congenital, although it may be acquired as a result of trauma or inflammation.
central cataract See nuclear cataract.
chalky cataract A cataract characterized by the presence of lime salt deposits.
Christmas tree cataract A rare type of diffuse age-related cataract in which the opacities appear as highly reflective crystals.
complicated cataract A cataract caused by or accompanying another intraocular disease, such as glaucoma, cyclitis, anterior uveitis or a hereditary retinal disorder such as retinitis pigmentosa or Leber's disease. Syn. secondary cataract. See cuneiform cataract; Leber's hereditary optic atrophy; retinitis pigmentosa; Down's syndrome; Fuchs' syndrome; rubella syndrome.
congenital cataract Cataract occurring as a result of faults in the early development of the lens. Some may be hereditary, usually autosomal dominant. The cause of others may be chromosomal abnormalities (e.g. Down's syndrome, Turner's syndrome), carbohydrate metabolic disorders (galactosaemia, galactokinase deficiency), rubella syndrome, etc. The condition requires urgent treatment to prevent the development of amblyopia. See capsular cataract; lamellar cataract; nuclear cataract; polar cataract; sutural cataract.
coronary cataract A cataract characterized by a series of opacities having the shape of a crown or ring near the periphery of the lens (Fig. C3).
cortical cataract Cataract affecting the cortex of the lens. The opacities often begin as spokes or isolated dots or clusters forming the cuneiform or subcapsular types of cataract, but eventually the opacity spreads through the entire cortex.
cuneiform cataract Age-related cataract characterized by opacities distributed within the periphery of the cortex of the lens in a radial manner, like spokes on a wheel (Fig. C3). See subcapsular cataract.
cupuliform cataract See sub-capsular cataract.
diabetic cataract Cataract associated with diabetes. In old eyes this type is similar to that of a non-diabetic person but in young eyes it is typically of the snowflake type.
diffuse cataract See blue-dot cataract; Christmas tree cataract.
electric cataract An opacity caused by an electric shock.
cataract extraction, extracapsular (ECCE) Surgical procedure for the removal of a cataractous crystalline lens. The anterior capsule is excised, the lens nucleus is removed and the residual equatorial cortex is aspirated. The posterior capsule may be polished. An intraocular lens implant may then be inserted. See after-cataract; biometry of the eye; capsulectomy; intraocular lens; Elschnig's pearls; phacoemulsification; Soemmering's ring.
cataract extraction, intracapsular (ICCE) Surgical procedure for the removal of a cataractous crystalline lens. The entire lens, together with its capsule, is removed. This procedure is rarely performed nowadays. See ligament of Wieger.
fluid cataract Hypermature cataract in which the lens substance has degenerated into milky fluid.
glassblower's cataract See heat-ray cataract.
heat-ray cataract Cataract due to excessive exposure to heat and infrared radiation. Syn. glassblower's cataract; thermal cataract. See exfoliation of the lens; infrared.
hypermature cataract The last stage in the development of age-related cataract in which the lens substance has disintegrated. See incipient cataract; intumescent cortical cataract; mature cataract; phacolytic glaucoma.
incipient cataract The first stage in the development of age-related cataract characterized by streaks similar to the spokes of a wheel or with an increased density of the nucleus. See intumescent cortical cataract; mature cataract; crystalline lens; second sight.
intumescent cortical cataract A stage of development of a cataract in which the lens, especially the cortex, absorbs fluid and swells. It may lead to secondary angle-closure glaucoma. The cataract can progress to the hypermature stage in which case the fluid leaks out, resulting in shrinkage of the lens and wrinkling of the anterior capsule, leaving the harder nucleus free within the capsule. See morgagnian cataract.
lamellar cataract A congenital cataract affecting one layer of the crystalline lens only. Syn. zonular cataract.
mature cataract The middle stage in the development of age-related cataract characterized by a completely opaque lens and considerable loss of vision. See hypermature cataract; incipient cataract.
morgagnian cataract A hypermature age-related cataract in which the cortex has shrunk and liquefied and the nucleus floats within the lens capsule. Degraded lens proteins may leak into the aqueous humour and cause phacolytic glaucoma. Syn. cystic cataract; sedimentary cataract. See intumescent cortical cataract.
nuclear cataract An opacity affecting the lens nucleus. It can be either congenital or age-related in origin. It frequently leads to an increase in myopia (or decrease in hyperopia). In some cases it reaches such a brown colour that it is called brunescent cataract (or brown cataract). Syn. central cataract (Fig. C3).
polar cataract A congenital opacity found at either pole of the crystalline lens. Anterior polar cataract may be flat or project as a conical opacity (pyramidal cataract) into the anterior chamber (Fig. C3). Posterior types may be associated with persistent hyaloid remnant (Mittendorf's dot).
punctate cataract See blue-dot cataract.
pyramidal cataract See polar cataract.
senile cataract See age-related cataract.
secondary cataract 1. Syn. for complicated cataract. 2. Syn. for after-cataract.
snowflake cataract A cataract characterized by greyish or whitish flakelike opacities. It is usually found in young diabetics or severe cases of diabetes (Fig. C3).
soft cataract Cataract in which the lens nucleus is soft. See crystalline lens.
subcapsular cataract An age-related opacity located beneath the anterior or posterior capsule. It may spread from the periphery of the cortex like spokes on a wheel (cuneiform cataract). This is the most common type of cortical cataract. The opacities may also be confined to the posterior layers of the cortex with a granular or lace-like appearance (cupuliform cataract). Subcapsular cataracts are often the result of radiation exposure, age, toxic damage (e.g. from corticosteroids), or secondary to eye diseases (e.g. uveitis, retinitis pigmentosa). (Fig. C3).
sunflower cataract See chalcosis lentis.
cataract surgery See capsulectomy; capsulorhexis; capsulotomy; extracapsular cataract extraction; intracapsular cataract extraction; phacoemulsification.
sutural cataract A congenital cataract in which the opacities are found along the anterior and/or posterior lens sutures. The opacities may appear Y-shaped or flower-shaped. The condition is often associated with Fabry's disease.
thermal cataract See heat-ray cataract.
traumatic cataract Cataract following injury to the lens, its capsule, or to the eyeball itself. It is commonly unilateral. Penetrating trauma of the lens causes rapid opacification of the cortex or even most of the lens contents. Concussion of the lens may result in capsular, subcapsular or cortical opacities. See Vossius' ring.
zonular cataract See lamellar cataract.
Fig. C3 Examples of cataracts (A, bipolar; B, pyramidal; C, axial; D, subcapsular (cupuliform); E, nuclear; F, coronary; G, snowflake; H, cuneiform)enlarge picture
Fig. C3 Examples of cataracts (A, bipolar; B, pyramidal; C, axial; D, subcapsular (cupuliform); E, nuclear; F, coronary; G, snowflake; H, cuneiform)
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann


Complete or partial opacity of the ocular lens.
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about cataract

Q. What Is a Cataract? My father has cataract in his eye, which interferes a lot with his vision. What is cataract?

A. A senile cataract (or clouding of the eye), 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. This condition as an effect on ones vision, and it is important to treat it early, as it becomes harder to treat as time goes by, and may eventually lead to blindness in that eye.

Q. What vitamin through diet shall I take to prevent cataract and how can I help my dad? My father recently had a cataract surgery. This was his second cataract surgery. After this surgery I got scared as what’s going wrong with my dad and he had the cataract the second time. As per the doctor, my dad must be short in vitamins in his diet. He has been given some vitamin tablets. I know that cataract is genetic. I guess I may also have cataract in my old age. What vitamin through diet shall I take to prevent cataract and how can I help my dad?

A. Yes, vitamins if not taken in required amount through diet may lead to vitamin deficiency. As deficiency in vitamin E -an antioxidant and vitamin B1 and B2 can lead to cataract. You must take them in required amount. Foods which have vitamin E are all vegetable oil, green leafy vegetables and egg. Cereals and fish are good source for vitamin B1 and vitamin B2 is surplus in milk and dairy products; eggs, cereals and green leafy vegetables.

Q. I had cataract surgery with iol implant, and ever since I have awful light sensitivity. Any ideas? I can't go into a "super store" without my sunglasses. My eyes ache at the end of the day. My doctor says "I don't know!"

A. May sound a bit silly question, but have you tried to consult your ophthalmologist (eye doctor, e.g. the one that performed the operation) about it? Cataract surgery, although considered very successful, isn't problem-free. Primary physician may not have the necessary specialization to deal with these subjects.

More discussions about cataract
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