cataract

Definition

A cataract is a cloudiness or opacity in the normally transparent crystalline lens of the eye. This cloudiness can cause a decrease in vision and may lead to eventual blindness.

Description

The human eye has several parts. The outer layer of the eyeball consists of a transparent dome-shaped cornea and an opaque, white sclera. The cornea and sclera help protect the eye. The next layer includes the iris, pupil, and ciliary body. The iris is the colored part of the eye and the pupil is the small dark round hole in the middle of the iris. The pupil and iris allow light into the eye. The ciliary body contains muscles that help in the eye's focusing ability. The lens lies behind the pupil and iris. It is covered by a cellophane-like capsule. The lens is normally transparent, elliptical in shape, and somewhat elastic. This elasticity allows the lens to focus on both near and far objects. The lens is attached to the ciliary body by fibers (zonules of Zinn). Muscles in the ciliary body act on the zonules, which then change the shape of the lens. This process is called accommodation—the lens focuses images to help make vision clear. As people age, the lens hardens and changes shape less easily. As a result, the accommodation process becomes more difficult, making it harder to see things up close. This generally occurs around the age of 40 and continues until about age 65. The condition is called presbyopia. It is a normal condition of aging, generally resulting in the need for reading glasses.

The lens is made up of approximately 35% protein and 65% water. As people age, degenerative changes in the lens' proteins occur. Changes in the proteins, water content, enzymes, and other chemicals are some of the reasons for the formation of a cataract.

The major areas of the lens are the nucleus, the cortex, and the capsule. The nucleus is in the center of the lens, the cortex surrounds the nucleus, and the capsule is the outer layer. Opacities can occur in any area of the lens. Cataracts, then, can be classified according to location (nuclear, cortical, or posterior subcapular cataracts). The density and location of the cataract determines the amount of vision affected. If the cataract forms in the area of the lens directly behind the pupil, vision may be significantly impaired. A cataract that occurs on the outer edges or side of the lens will create less of a visual problem.

Cataracts in the elderly are so common that they are thought to be a normal part of the aging process. Between the ages of 52 and 64, there is a 50% chance of having a cataract, while at least 70% of those 70 and older are affected. Cataracts associated with aging (senile or age-related cataracts) most often occur in both eyes, with each cataract progressing at a different rate. Initially, cataracts may not affect vision. If the cataract remains small or at the periphery of the lens, the visual changes may be minor.

Cataracts that occur in people other than the elderly are much less common. Congenital cataracts occur very rarely in newborns. Genetic defects or an infection or disease in the mother during pregnancy are among the causes of congenital cataracts. Traumatic cataracts may develop after a foreign body or trauma injures the lens or eye. Systemic illnesses, such as diabetes, may result in cataracts. Cataracts can also occur secondary to other eye diseases—for example, an inflammation of the inner layer of the eye (uveitis) or glaucoma. Such cataracts are called complicated cataracts. Toxic cataracts result from chemical toxicity, such as steroid use. Cataracts can also result from exposure to the sun's ultraviolet (UV) rays.

— Cynthia L. Frozena, RN

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

[Middle English cataracte, from Old French, from Latin cataracta, from Greek katarraktēs, kataraktēs, downrush, waterfall, portcullis, probably from katarassein, to dash down (kat-, kata-, cata- + arassein, to strike). Sense 3, from a comparison to a portcullis or other falling impediment or covering.]

(KAT-uh-rakt)

noun
1. A clouding of the naturally occurring crystalline lens.
2. A waterfall.

Etymology
From Latin cataracta (waterfall, portcullis), from Greek katarahaktes (downpour), from Greek katarassein (down rush), from Greek kata (down) + arassein (to strike). The medical term cataract stems from the sense of portcullis which is a falling gate or covering

The whitish appearance of onrushing water, cascading down a waterfall, is exactly what a dense cataract looks like through the pupil -- it can be a whitish, sometimes vertically streaked density. The cataract itself, in medical terms, is a clouding of the normally clear crystalline lens.
In the 1500s, the term cataract began to be applied to the whitish clouding of dense clouding of the crystalline lens. The lens, along with the cornea, focuses light rays onto the retina, which is how we see. As a cataract develops, our vision progressively blurs and objects become duskier and browner (brunescent) because blue and violet rays are preferentially absorbed by the cataractous lens, leaving largely the murkier reds and browns to pass through.
The last works of the French impressionist painter Claude Monet (1840-1926), especially his Japanese footbridge paintings and the "House from the Rose Garden" series painted at his home at Giverny, show this brunescent change over time. Monet's right cataract was removed in January, 1923, and works painted after this time show a return of the blues and violets to his artistic palette. In fact, his magisterial "Waterlilies" series of 22 murals (Les Nympheas), finally completed right before his death in 1926 and now spectacularly viewable in the refurbished Orangerie in Paris, show the subtle blues and greens of the lily pads on the ponds.
The other definition of cataract is waterfall. The six large waterfalls of the Nile river are usually called the cataracts of the Nile, near one of which was built the Aswan Dam.
-Guest wordsmith Vincent de Luise, MD (eyemusic73ATaol.com)

Any clouding or opacity of the crystalline lens of the eye. The essential biochemical change in a cataractous lens is the coagulation of its protein. Cataracts vary markedly in degree of density and may be due to many causes, but the majority are associated with aging. Cataracts are the single leading cause of blindness in the world.

Senile cataract occurs with aging and is by far the most common type. Progressively blurred vision is the only symptom. There are a number of other varieties (congenital, metabolic, secondary, or traumatic) and causes (such as a reaction to certain drugs or irradiation). Cataracts may also be associated with systemic diseases such as hypoparathyroidism, myotonic dystrophy, atopic dermatitis, galactosemia, and Lowe's, Werner's, and Down syndromes.

At present the treatment for cataracts, when they are sufficiently advanced to impair the vision, is surgical removal. When a cataract is surgically removed, the crystalline lens of the eye is removed much as a lens would be removed from a camera. In order to restore normal vision after surgery, any of a number of methods may be followed: cataract glasses may be prescribed; contact lenses may be fitted; or intraocular lenses made of the plastic polymethylmethacrylate can be inserted into the eye to replace the cataractous lens. See also Eye (vertebrate).

noun

An abundant, usually overwhelming flow or fall, as of a river or rain: alluvion, cataclysm, deluge, downpour, flood, freshet, inundation, Niagara, overflow, torrent. Chiefly British spate. See big/small/amount.

An abnormal progressive condition of the lens of the eye, characterized by loss of transparency.

Definition

A cataract is a cloudiness or opacity in the normally transparent crystalline lens of the eye. This cloudiness can cause loss of vision and may lead to eventual blindness.

Description

The human eye has several parts. The outer layer of the eyeball consists of a transparent dome-shaped cornea and an opaque white sclera, which is a fibrous membrane. The cornea and sclera help protect the eye. The next layer includes the iris, pupil, and ciliary body. The iris is the colored part of the eye; the pupil is the small dark round hole in the middle of the iris. The pupil and iris allow light into the eye. The ciliary body contains muscles that help the eye to focus. The lens lies behind the pupil and iris. It is covered by a cellophane-like capsule. The lens is normally transparent, elliptical in shape, and somewhat elastic. This elasticity allows the lens to focus on both near and far objects. The lens is attached to the ciliary body by fibers (zonules of Zinn). Muscles in the ciliary body act on the zonules, which then change the shape of the lens. This changing of shape is called accommodation. As people age, the lens hardens and accommodates less easily, which makes it harder for the person to see close objects. This hardening of the lens generally occurs around the age of 40 and continues until about age 65. The condition is called presbyopia. It is a normal condition of aging, generally resulting in the need for reading glasses.

The lens is made up of approximately 35% protein and 65% water. As people age, the proteins in the lens begin to degenerate. Changes in the proteins, water content, enzymes, and other chemicals are some of the causes of cataract formation.

The major parts of the lens are the nucleus, the cortex, and the capsule. The nucleus is in the center of the lens, the cortex surrounds the nucleus, and the capsule is the outer layer. Opaque areas can develop in any part of the lens. Cataracts, then, can be classified according to location (nuclear, cortical, or posterior subcapular cataracts). The density and location of the cataract determines the extent of vision affected. If the cataract forms in the area of the lens directly behind the pupil, the person's vision may be significantly impaired. A cataract that occurs on the outer edges or side of the lens will cause less severe impairment.

Cataracts in the elderly are so common that they are considered a normal part of the aging process. People between the ages of 52–64 have a 50% chance of developing a cataract, while at least 70% of those 70 and older are affected. Cataracts associated with aging (senile or age-related cataracts) most often occur in both eyes, with each cataract progressing at a different rate. At first, these cataracts may not affect vision. If the cataract remains small or at the periphery of the lens, the visual changes may be minor.

Cataracts that occur in people other than the elderly are much less common. Congenital cataracts occur very rarely in newborns. Genetic defects or an infection or disease in the mother during pregnancy are among the causes of congenital cataracts. There is a condition called blue cataracts, which is inheritance-linked and affects primarily Tibetans and some other Asians. Traumatic cataracts may develop after an injury or foreign body damages the lens or eye. Systemic illnesses like diabetes may result in cataracts. Cataracts can also occur secondary to other eye diseases—for example, an inflammation of the inner layer of the eye (uveitis) or glaucoma. Such cataracts are called complicated cataracts. Toxic cataracts result from chemical toxicity, such as steroid use. Cataracts can also result from exposure to the sun's ultraviolet (UV) rays.

Causes & Symptoms

Recent studies have been conducted to determine whether diet or the use of vitamins might have an effect on the formation of cataracts in older people. Although debate continues, several studies reported in late 2001 that a diet rich in certain caretenoids may protect against development of cataracts. Likewise, there has been considerable interest in the use of antioxidant supplements as a protection against cataracts. Such antioxidant vitamins as vitamins A, C, E, and beta-carotene protect body tissues against free radicals, which are byproducts of oxidation. Vitamin C in particular, has shown the strongest impact on lower rates of cataracts. Some vitamins are marketed specifically for the eyes. Patients should speak to their doctors about the use of such vitamins.

Studies also have recently linked changes in lens proteins to cataract formation. Soluble proteins in the lens begin to condense and form clumps, leading to cataracts. Researchers have identified mutations in genes that likely lead to protein changes resulting in juvenile cataracts. The next step is to study a possible genetic relationship to formation of age-related cataracts as well.

Smoking and alcohol intake have been implicated in cataract formation. Some studies have determined that a diet high in fat will increase the likelihood of cataract formation, while eating more foods rich in antioxidants will lower the risk. More research is needed to determine if diet, smoking, alcohol consumption, or vitamins have any connection to the formation of cataracts.

Cataracts may have the following symptoms:

• gradual, painless onset of blurry, filmy, or fuzzy vision
• poor central vision
• frequent changes in eyeglass prescription
• changes in color vision
• increased glare from lights, especially oncoming headlights when driving at night
• "second sight" improvement in near vision (no longer needing reading glasses), but a decrease in distance vision
• spoor vision in sunlight
• the presence of a milky whiteness in the pupil as the cataract progresses

Diagnosis

Both ophthalmologists and optometrists may detect and monitor cataract growth and prescribe prescription lenses for visual deficits. Only an ophthalmologist, however, can perform cataract extraction.

Cataracts are easily diagnosed from the reporting of symptoms, a visual acuity examination using an eye chart, and by a physician or optometrist's examination of the eye. Shining a penlight into the pupil may reveal opacities or a color change of the lens even before the patient develops visual symptoms. A slit lamp, which is basically a large microscope, allows the doctor to examine the front of the eye and the lens, and to determine the location of the cataract.

Some other diagnostic tests may be used to determine if cataracts are present or how much improvement the patient may have after surgery. These tests include a glare test, potential vision test, and contrast sensitivity test.

Treatment

Because free radicals have been implicated as a cause of cataracts, alternative therapies emphasize the importance of a healthful diet, nutritional supplements and/or herbal remedies to prevent and slow down the progression of cataracts.

Nutritional Therapy

A naturopathic doctor or a nutritionist may recommend the following dietary changes:

• Reduce consumption of salty or fatty foods. Diabetics should also limit their intake of milk and other dairy products.
• Increase intake of foods that are high in beta-carotene: peaches, apricots, berries, carrots, and leafy green vegetables. Beta-carotene and other antioxidants can protect against or slow down the development of cataracts.
• Stop cigarette smoking and avoid exposure to secondhand smoke.
• Eat a diet rich in fruits and vegetables with high concentrations of vitamin C. Take supplemental vitamin C (1 g three times daily) and vitamin A (25,000 IU per day).
• Take supplemental beta-carotene (25,000–100,000 IU per day) and selenium (400 mcg per day). Low selenium levels may increase the risk of cataracts.
• Increase intake of L-cysteine (400 mg per day), L-glutamine (200 mg per day), and L-glycine (200 mg per day). These three amino acids may be beneficial to some cataract patients.
• Add other supplements: zinc, lutein, riboflavin, and cod liver oil.

Herbal Therapy

There are two herbal remedies that may help protect the eyes against cataracts:

• Bilberries (40–80 mg daily). Early research indicates that eating bilberries may halt cataract progression.
• Hachimijiogan. Hachimijiogan is an ancient Chinese herbal formula. Animal studies suggest that it may protect the eyes against cataracts by increasing the glutathione content of the lens.

Allopathic Treatment

Cataracts that cause no symptoms or only minor visual changes may not require any treatment. An ophthalmologist or optometrist should continue to monitor and assess the cataract at scheduled office visits. Stronger prescription eyeglasses or contact lenses may be helpful.

Cataract surgery is the only option for patients whose cataracts interfere with vision to the extent of affecting their daily lives. It is the most frequently performed surgery in the United States. It generally improves vision in over 90% of patients. Some people have heard that a cataract should be "ripe" before being removed. A "ripe" or mature cataract means that the lens is completely opaque. Most cataracts are removed before they reach that stage. Sometimes cataracts need to be removed so that the doctor can examine the back of the eye more carefully. Patients with diseases that may affect the eye may require cataract surgery for this reason. If cataracts are present in both eyes, only one eye at a time should be operated on. Healing occurs in the first eye before the second cataract is removed, sometimes as early as the following week. A final eyeglass prescription is usually given about four to six weeks after surgery. Patients will still need reading glasses. The overall health of the patient needs to be considered in making the decision to operate. Age alone, however, need not preclude effective surgical treatment of cataracts; people in their 90s can benefit from cataract surgery.

Patients are given antibiotic drops to prevent infection and steroids to reduce inflammation after surgery. An eye shield or glasses during the day will protect the eye from injury while it heals. At night, the patient should wear an eye shield. The patient returns to the doctor the day after surgery for assessment, with several follow-up visits over the next two months to monitor the healing process.

Expected Results

The success rate of cataract extraction is very high, with a good prognosis. Visual acuity of 20/40 or better may be achieved. If an extracapsular cataract extraction was performed, a secondary cataract may develop in the remaining back portion of the capsule one to two years after surgery. YAG capsulotomy is most often used to treat this type of cataract. YAG stands for yttrium aluminum garnet, the name of the laser used for this procedure. The laser beam makes a small opening in the remaining back part of the capsule, allowing light through.

Complications occur in a very small percentage (3–5%) of surgical cataract extractions. Infections, swelling of the cornea (edema), bleeding, retinal detachment, and the onset of glaucoma have been reported. Any haziness, redness, decrease in vision, nausea, or pain should be reported to the surgeon immediately.

Prevention

Preventive measures emphasize protecting the eyes from UV radiation by wearing glasses with a special coating to protect against UV rays. Dark lenses alone are not sufficient. The lenses must protect against UV light (specifically, UV-A and UV-B). Antioxidants and herbal remedies may also provide some protection by reducing free radicals that can damage lens proteins. A healthful diet rich in sources of antioxidants, including citrus fruits, sweet potatoes, carrots, green leafy vegetables, and/or vitamin supplements may be helpful. When taking certain medications, such as steroids, more frequent eye exams may be necessary. Patients should speak to their doctors to see if medications may affect their eyes.

Resources

Books

"Cataract." Medical-Surgical Nursing: Concepts and Clinical Practice, fifth edition. Edited by Wilma J. Phipps et al. St. Louis, MO: Mosby-Year Book, Inc., 1995.

Liberman, Shari, and Nancy Bruning. The Real Vitamin & Mineral Book: Using Supplements for Optimal Health,, 2nd ed. Garden City Park, NY: Avery Publishing Group, 1997.

Murray, Michael, and Joseph Pizzorno. Encyclopedia of Natural Medicine. Revised second ed. Rocklin, CA: Prima Health, 1997.

Periodicals

Friedrich, MJ. "Insight Into Opacity: Clues to Cataract Formation." JAMA, The Journal of the American Medical Association 286 no. 14 (October 10, 2001): 1705.

"Nutrients May Prevent Age-Related Eye Diseases." Health and Medicine Week (November 26,2001): 2.

Organizations

American Academy of Ophthalmology (National Eyecare Project). P.O. Box 429098. San Francisco, CA 94142-9098. (800) 222-EYES. http://www.eyenet.org.

American Optometric Association. 243 North Lindbergh Blvd. St. Louis, MO 63141. (314) 991-4100. http://www.aoanet.org.

The Lighthouse. 111 East 59th Street. New York, NY 10022. (800) 334-5497. http://www.lighthouse.org.

Prevent Blindness America. 500 East Remington Road. Schaumburg, IL 60173. (800) 331-2020. http://www.prevent-blindness.org.

[Article by: Teresa G. Odle]

Cataract, the leading cause of blindness worldwide, is a clouding of the crystalline lens of the eye. Symptoms of cataract include blurred vision, difficulty reading print and street signs, light sensitivity, and glare disability. Most cataracts are agerelated, but environmental factors such as ultraviolet light exposure, tobacco smoking, diabetes mellitus, trauma, certain congenital infections, and some medications can accelerate their growth. In some hereditary conditions, such as galactosemia, a single gene defect is responsible. Treatment of visually significant cataract, which is highly successful, involves surgically removing the cloudy lens and implanting a clear plastic replacement lens.

(SEE ALSO: Vision Disorders)

— KEVIN M. MILLER

A step-like succession of waterfalls. Cataracts, such as those on the Nile, are often associated with the ‘rungs’ formed by the erosion of horizontally bedded rocks.

For more information on cataract, visit Britannica.com.

A loss in the transparency of the lens of the eye, which reduces a person's ability to see. The condition can be treated by surgically removing the lens and replacing it with an artificial one, or with corrective eyeglasses or contact lenses.

For other uses, see Cataract (disambiguation).

Cataract
Classification and 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

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. 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. Cataracts typically progress slowly to cause vision loss and are potentially blinding if untreated. The condition usually affects both the eyes, but almost always one eye is affected earlier than the other.^[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. 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 some perception of light was restored in the cataractous patients.

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]). 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". 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]

Contents 1 Causes 2 Symptoms 3 Epidemiology 4 Cataract surgery 5 Historical 6 Current surgical practices 7 Prevention 8 Recent research 9 Types of cataracts 10 Associations with systemic conditions 11 See also 12 References and notes 13 External links

Causes

Cataracts develop from a variety of reasons, including long-term exposure to ultraviolet light, exposure to radiation, secondary effects of diseases such as diabetes, hypertension and advanced age, or trauma (possibly much earlier); they are usually a result of denaturation of lens protein. 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 are 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.^[7] 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. Atopic or allergic conditions are also known to quicken the progression of cataracts, especially in children.^[8]

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

Some drugs can induce cataract development, such as corticosteroids^[9] and Ezetimibe^{[citation needed]} and Seroquel.

There are various types of cataracts, e.g. nuclear, cortical, mature, and hypermature. Cataracts are also classified by their location, e.g. posterior (classically due to steroid use^[9][10]) and anterior (common (senile) cataract related to aging).

Symptoms

As a cataract becomes more opaque, clear vision is compromised. A loss of visual acuity is noted. Contrast sensitivity is also lost, so that contours, shadows and color vision are less vivid. Veiling glare can be a problem as light is scattered by the cataract into the eye. A contrast sensitivity test should be performed and if a loss in contrast sensitivity is demonstrated an eye specialist consultation is recommended.

In the developed world, particularly in high-risk groups such as diabetics, it may be advisable to seek medical opinion if a 'halo' is observed around street lights at night, especially if this phenomenon appears to be confined to one eye only.

Epidemiology

Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people, according to the World Health Organization (WHO).^[11] 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,^[12] 60% of those between the ages 65 and 74,^[13] and 91% of those between the ages of 75 and 85.^[12]

The increase in ultraviolet radiation resulting from depletion of the ozone layer is expected to increase the incidence of cataracts.^[14]

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

Historical

The earliest records are from the Bible as well as early Hindu records.^[15] Early cataract surgery was developed by the Indian surgeon, Sushruta (6th century BCE).^[16] The Indian tradition of cataract surgery was performed with a special tool called the Jabamukhi Salaka, a curved needle used to loosen the lens and push the cataract out of the field of vision.^[16] The eye would later be soaked with warm butter and then bandaged.^[16] Though this method was successful, Sushruta cautioned that it should only be used when necessary.^[16] Greek physicians and philosophers traveled to India where these surgeries were performed by physicians.^[16] The removal of cataract by surgery was also introduced into China from India.^[17]

The first references to cataract and its treatment in Ancient Rome are found in 29 AD in De Medicinae, the work of the Latin encyclopedist Aulus Cornelius Celsus.^[18] The Romans were pioneers in the health arena—particularly in the area of eye care.^[19]

The Iraqi ophthalmologist Ammar ibn Ali of Mosul performed the first extraction of cataracts through suction. He invented a hollow metallic syringe hypodermic needle, which he applied through the sclerotic and extracted the cataracts using suction.^[20] In his Choice of Eye Diseases, written in circa 1000, he wrote of his invention of the hypodermic needle and how he discovered the technique of cataract extraction while experimenting with it on a patient.^[21]

Current surgical practices

When a cataract is 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. 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).

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.

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.

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.

Complications are possible after cataract surgery, including endophthalmitis, posterior capsular opacification and retinal detachment.

In ICCE there is the issue of the Jack in the box phenomenon ^[22] 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.^[23][24] 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.^[25]

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 an at-risk population may be associated with a lower risk of developing nuclear cataract disease.^[26]

Research is scant and mixed but weakly positive for the nutrients lutein and zeaxanthin.^{[27][28][29][30]} Bilberry extract shows promise in rat models ^[31][32] and in clinical studies.^[33]

In the past few years, eye drops containing acetyl-carnosine have been used by several thousands cataract patients across the world. The drops are believed to work by reducing oxidation and glycation damage in the lens, particularly reducing cristallin cross-linking ^[34], ^[35]. The use of these drops remains controversial due to lack of large properly designed trials.

Types of cataracts

Bilateral cataracts in an infant due to Congenital rubella syndrome

The following is a classification of the various types of cataracts. This is not comprehensive and other unusual types may be noted.

• Classified by etiology

• Age-related cataract

• Cortical Senile 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

• Senile Nuclear Cataract

• Cataracta brunescens
• cataracta nigra
• cataracta rubra

• 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 (PCO) subsequent to a successful extracapsular cataract surgery (usually within three months to two years) with or without IOL implantation. Requires a quick & painless office procedure with Nd:YAG laser capsulotomy to restore optical clarity.

Associations with systemic conditions

• Chromosomal disorders

• 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

• Atopic dermatitis
• Basal-cell nevus syndrome
• Ichthyosis
• Pemphigus

• Metabolic and nutrition diseases

• Aminoaciduria (Lowe's syndrome)
• Diabetes mellitus
• Fabry's disease
• Galactosemia / galactosemic cataract
• Homocystinuria
• Hypervitaminosis D
• Hyperparathyroidism
• Hypothyroidism
• Mucopolysaccharidoses
• Wilson's disease

• Infectious diseases

• Congenital

• Congenital herpes simplex
• Congenital syphilis
• Cytomegalic inclusion disease
• Rubella

• Others

• Cysticercosis
• Leprosy
• Onchocerciasis
• Toxoplasmosis

• Toxic substances introduced systemically

• Corticosteroids
• Haloperidol
• Miotics
• Triparanol

See also

• List of eye diseases and disorders
• List of systemic diseases with ocular manifestations
• List of eye diseases

References and notes

• Pavan-Langston, Deborah (1990). Manual of Ocular Diagnosis and Therapy. Little, Brown and Company.

1. ^ Common Causes of Vision Loss in Elderly Patients - July 1999 - American Academy of Family Physicians
2. ^ eMedicine - Cataract, Senile : Article by Vicente Victor D Ocampo. From eMedicine The Continually Updated Clinical Reference
3. ^ Dictionary.com/Word of the Day Archive/cataract
4. ^ Online Etymology Dictionary
5. ^ Mistaken Science - Topic Powered by eve community. Wordcraft Forums
6. ^ 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
7. ^ Rafnsson, V; Olafsdottir E, Hrafnkelsson J, Sasaki H, Arnarsson A, Jonasson F (2005). "Cosmic radiation increases the risk of nuclear cataract in airline pilots: a population-based case-control study". Arch Ophthalmol 123: 1102–1105. doi:10.1001/archopht.123.8.1102. PMID 16087845. 
8. ^ Chen CC, Huang JL, Yang KD, Chen HJ (March 2000). "Atopic cataracts in a child with atopic dermatitis: a case report and review of the literature". Asian Pac. J. Allergy Immunol. 18 (1): 69–71. PMID 12546060. 
9. ^ ^{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. 
10. ^ Greiner J, Chylack L (1979). "Posterior subcapsular cataracts: histopathologic study of steroid-associated cataracts". Arch Ophthalmol 97 (1): 135–44. PMID 758890. 
11. ^ WHO | Priority eye diseases.
12. ^ ^{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.
13. ^ 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.
14. ^ Dobson, R. (2005). "Ozone depletion will bring big rise in number of cataracts". BMJ 331 (7528): 1292. doi:10.1136/bmj.331.7528.1292-d. PMID 16322012.  edit
15. ^ A short history of cataract surgery
16. ^ ^{a b c d e} Finger, page 66
17. ^ Lade & Svoboda, page 85
18. ^ Cataract history
19. ^ The Romans carried out cataract ops, February 9, 2008, BBC News
20. ^ Ibrahim B. Syed PhD, "Islamic Medicine: 1000 years ahead of its times", Journal of the International Society for the History of Islamic Medicine 2 (2002): 2-9 [7].
21. ^ Finger, Stanley (1994), Origins of Neuroscience: A History of Explorations Into Brain Function, Oxford University Press, p. 70, ISBN 0195146948 
22. ^ [http://i498.photobucket.com/albums/rr347/medicinedecoded/jackinbox.jpg Roving ring scotoma &Jack-in-the-box Phenomenon in Aphakic spectacles - December 2008 - Medicine Decoded
23. ^ Neale, RE; JL Purdie, LW Hirst, and AC Green (2003-11). "Sun exposure as a risk factor for nuclear cataract". Epidemiology (journal)/Epidemiology 14 (6): 707-712. PMID 14569187. 
24. ^ 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
25. ^ 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
26. ^ Klein, Barbara; Ronald Klein, Kristine Lee, and Lisa Grady (2006). "Statin Use and Incident Nuclear Cataract". Journal of the American Medical Association 295 (23): 2752–2758. doi:10.1001/jama.295.23.2752. PMID 16788130. 
27. ^ 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
28. ^ Invest Ophthalmol Vis Sci. 2006 Sep;47(9):3783-6. Lutein and zeaxanthin and the risk of cataract: the Melbourne visual impairment project
29. ^ 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
30. ^ J Am Coll Nutr. 2004 Dec;23(6 Suppl):567S-587S Lutein and zeaxanthin and their potential roles in disease prevention
31. ^ Dietary supplementation with bilberry extract prevents macular degeneration and cataracts in senesce-accelerated OXYS rats Adv Gerontol. 2005;16:76-9
32. ^ Yamakoshi J, et al. J Agric Food Chem. 2002 Aug 14;50(17):4983-8.
33. ^ Ann Ottalmol Clin Ocul, 1989
34. ^ Williams DL, Munday P. The effect of a topical antioxidant formulation including N-acetyl carnosine on canine cataract: a preliminary study. Vet Ophthalmol. 2006;9(5):311-6
35. ^ Guo Y, Yan H. Preventive effect of carnosine on cataract development. Yan Ke Xue Bao. 2006; 22(2):85-8

External links

• Cataract Resource Guide from the National Eye Institute (NEI).
• eMedicine Health
• The Childhood Cataract Network
• Pediatric Glaucoma and Cataract Family Association

v • d • e Eye disease · pathology of the eye (H00-H59, 360-379) Adnexa eyelid: inflammation (Stye, Chalazion, Blepharitis) · Entropion · Ectropion · Lagophthalmos · Blepharochalasis · Ptosis · Blepharophimosis · Xanthelasma · Trichiasis · Madarosis lacrimal system: Dacryoadenitis · Epiphora · Dacryocystitis orbit: Exophthalmos · Enophthalmos Globe Conjunctiva Conjunctivitis (Allergic conjunctivitis) · Pterygium · Pinguecula · Subconjunctival hemorrhage Fibrous tunic sclera: Scleritis cornea: Keratitis (Herpetic keratitis, Acanthamoeba keratitis, Fungal keratitis) · Corneal ulcer · Snow blindness · Thygeson's superficial punctate keratopathy · Corneal dystrophy (Fuchs', Meesmann) · Keratoconus · Keratoconjunctivitis sicca · Arc eye · Keratoconjunctivitis · Corneal neovascularization  · Kayser-Fleischer ring · Arcus senilis · Band keratopathy Iris and ciliary body Iritis · Uveitis (Intermediate uveitis) · Iridocyclitis · Hyphema · Rubeosis iridis · Persistent pupillary membrane · Iridodialysis · Synechia Lens Cataract · Aphakia · Ectopia lentis Choroid Choroideremia · Choroiditis (Chorioretinitis) Retina Retinitis (Chorioretinitis, Cytomegalovirus retinitis) · Retinal detachment · Retinoschisis · Ocular ischemic syndrome/Central retinal vein occlusion · Retinopathy (Bietti's crystalline dystrophy, Coats disease, Diabetic retinopathy, Hypertensive retinopathy, Retinopathy of prematurity) · Macular degeneration · Retinitis pigmentosa · Retinal haemorrhage · Central serous retinopathy · Macular edema · Epiretinal membrane · Macular pucker · Vitelliform macular dystrophy · Leber's congenital amaurosis · Birdshot chorioretinopathy Optic nerve and visual pathways Optic neuritis · Papilledema · Optic atrophy · Leber's hereditary optic neuropathy · Dominant optic atrophy · Optic disc drusen · Glaucoma · Toxic and nutritional optic neuropathy · Anterior ischemic optic neuropathy Ocular muscles, binocular movement, accommodation and refraction Paralytic strabismus: Ophthalmoparesis · Progressive external ophthalmoplegia · Palsy (III, IV, VI) · Kearns-Sayre syndrome Other strabismus: Esotropia/Exotropia · Hypertropia · Heterophoria (Esophoria, Exophoria) · Brown's syndrome · Duane syndrome Other binocular: Conjugate gaze palsy · Convergence insufficiency · Internuclear ophthalmoplegia · One and a half syndrome Refractive error: Hyperopia/Myopia · Astigmatism · Anisometropia/Aniseikonia · Presbyopia Visual disturbances and blindness Amblyopia · Leber's congenital amaurosis  · Subjective (Asthenopia, Hemeralopia, Photophobia, Scintillating scotoma) · Diplopia · Scotoma · Anopsia (Binasal hemianopsia, Bitemporal hemianopsia, Homonymous hemianopsia, Quadrantanopia) · Color blindness (Achromatopsia, Dichromacy, Monochromacy) · Nyctalopia (Oguchi disease) · Blindness/Low vision Pupil Anisocoria · Argyll Robertson pupil · Marcus Gunn pupil · Adie syndrome · Miosis · Mydriasis · Cycloplegia Eye infections Trachoma · Onchocerciasis Other Nystagmus · Glaucoma/Ocular hypertension · Floater · Leber's hereditary optic neuropathy · Red eye · Keratomycosis · Xerophthalmia · Phthisis bulbi eye navs: anat/adnexa anat/pathways/physio/dev, noncongen/congen/neoplasia, eponymous signs, proc

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Dansk (Danish)
n. - vandfald, syndflod, grå stær

Nederlands (Dutch)
cataract, grauwe staar, stortbui, waterval

Français (French)
n. - (Méd) cataracte, cataracte, cascade

Deutsch (German)
n. - Wasserfall, grauer Star

Ελληνική (Greek)
n. - καταρράκτης, (παθολ.) καταρράκτης

Italiano (Italian)
cascata, cateratta, cataratta

Português (Portuguese)
n. - catarata (f), cachoeira (f), inundação (f)

Русский (Russian)
катаракта, водопад, ливень

Español (Spanish)
n. - catarata, cataratas

Svenska (Swedish)
n. - vattenfall, grå starr

中文（简体）(Chinese (Simplified))
大瀑布, 白内障, 奔流

中文（繁體）(Chinese (Traditional))
n. - 大瀑布, 白內障, 奔流

한국어 (Korean)
n. - 큰 폭포, 백내장, 수력 절동기

日本語 (Japanese)
n. - 大滝, 瀑布, 豪雨, 白内障, 混濁部, 大雨

العربيه (Arabic)
‏(الاسم) مرض سد الماء الأزرق (أو ألابيض) في العيون, شلال‏

עברית (Hebrew)
n. - ‮מפל-מים, ירוד (מחלה), תבלול‬

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