senile cataract

WordNet

1. an eye disease that involves the clouding or opacification of the natural lens of the eye
2. a large waterfall; violent rush of water over a precipice

PrepTutorEJDIC

1. 〈C〉大滝 / 〈C〉《複数形で》奔流 / 〈U〉〈C〉白内障,白そこひ
2. 老年の,老衰の,(特に)もうろくした

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/05 16:47:50」(JST)

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For other uses, see Cataract (disambiguation).

Cataract
Magnified view of a cataract seen on examination with a slit lamp
Classification and external resources
Specialty	Ophthalmology
ICD-10	H25-H26, H28, Q12.0
ICD-9-CM	366
DiseasesDB	2179
MedlinePlus	001001
eMedicine	article/1210914
MeSH	D002386

A cataract is a clouding of the lens in the eye leading to a decrease in vision. It can affect one or both eyes. Often it develops slowly. Symptoms may include faded colors, blurry vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision may also result in an increased risk of falling and depression. Cataracts are the cause of half of blindness and 33% of visual impairment worldwide.

Cataracts are most commonly due to aging, but may also occur due to trauma, radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, smoking tobacco, prolonged exposure to sunlight, and alcohol. Either clumps of protein or yellow-brown pigment may be deposited in the lens reducing the transmission of light to the retina at the back of the eye. Diagnosis is by an eye examination.

Prevention includes wearing sunglasses and not smoking. Early on the symptoms may be improved with eyeglasses. If this does not help, surgery to remove the cloudy lens and replace it with an artificial lens is the only effective treatment. Surgery is only needed if the cataracts are causing problems. Surgery generally results in an improved quality of life. Cataract surgery is not easily available in many countries, which is especially true for women.

About 20 million people globally are blind due to cataracts. It is the cause of about 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America. Blindness from cataracts occurs in about 10 to 40 per 100,000 children in the developing world and 1 to 4 per 100,000 children in the developed world. Cataracts become more common with age. About half the people in the United States have had cataracts by the age of 80.

Signs and symptoms

An example of normal vision on the left versus vision with cataracts on the right

Bilateral cataracts in an infant due to congenital rubella syndrome

Signs and symptoms vary depending on the type of cataract, though considerable overlap occurs. People with nuclear sclerotic or brunescent cataracts often notice a reduction of vision. Those with posterior subcapsular cataracts usually complain of glare as their major symptom.

The severity of cataract formation, assuming no other eye disease is present, is judged primarily by a visual acuity test. The appropriateness of surgery depends on a patient's particular functional and visual needs and other risk factors, all of which may vary widely.

Causes

Age

Age is the most common cause. Lens proteins denature and degrade over time, and this process is accelerated by diseases such as diabetes mellitus and hypertension. Environmental factors, including toxins, radiation, and ultraviolet light, have cumulative effects, which are worsened by the loss of protective and restorative mechanisms due to alterations in gene expression and chemical processes within the eye.

Trauma

Blunt trauma causes swelling, thickening, and whitening of the lens fibers. While the swelling normally resolves with time, the white color may remain. In severe blunt trauma, or injuries which penetrate the eye, the capsule in which the lens sits can be damaged. This allows water from other parts of the eye to rapidly enter the lens leading to swelling and then whitening, obstructing light from reaching the retina at the back of the eye. Cataracts may develop in 0.7 to 8.0% of cases following electrical injuries.

Radiation

Ultraviolet light, specifically UVB, has been shown to cause cataracts, and some evidence indicates sunglasses worn at an early age can slow its development in later life. The lens filters UV light; so once it is removed via surgery, one may be able to see UV light. Microwave radiation has also been found to cause cataracts. The mechanism is unclear, but may include changes in heat-sensitive enzymes that normally protect cell proteins in the lens. Another possible mechanism is direct damage to the lens from pressure waves induced in the aqueous humor. Cataracts have also been associated with ionizing radiation such as X-rays. The addition of damage to the DNA of the lens cells also has been considered. Finally, electric and heat injuries denature and whiten the lens as a result of direct protein coagulation. This same process makes the clear albumin of an egg become white and opaque after cooking. Cataracts of this type are often seen in glassblowers and furnace workers. Lasers of sufficient power output are known to damage the eyes and skin.

Genetics

The genetic component is strong in the development of cataracts, most commonly through mechanisms that protect and maintain the lens. The presence of cataracts in childhood or early life can occasionally be due to a particular syndrome. Examples of chromosome abnormalities associated with cataracts include 1q21.1 deletion syndrome, cri-du-chat syndrome, Down syndrome, Patau's syndrome, trisomy 18 (Edward's syndrome), and Turner's syndrome, and in the case of neurofibromatosis type 2, juvenile cataract on one or both sides may be noted. Examples of single-gene disorder include Alport's syndrome, Conradi's syndrome, myotonic dystrophy, and oculocerebrorenal syndrome or Lowe syndrome.

Skin diseases

The skin and the lens have the same embryological origin and can be affected by similar diseases. Those with atopic dermatitis and eczema occasionally develop shield ulcers cataracts. Ichthyosis is an autosomal recessive disorder associated with cuneiform cataracts and nuclear sclerosis. Basal-cell nevus and pemphigus have similar associations.

Drug use

Cigarette smoking has been shown to double the rate of nuclear sclerotic cataracts and triple the rate of posterior subcapsular cataracts. Evidence is conflicting over the effect of alcohol. Some surveys have shown a link, but others which followed patients over longer terms have not.

Medications

Some drugs, such as corticosteroids, can induce cataract development. People with schizophrenia often have risk factors for lens opacities (such as diabetes, hypertension, and poor nutrition) but antipsychotic medications are unlikely to contribute to cataract formation. Miotics and triparanol may increase the risk.

Iatrogenic

Nearly every person who undergoes a vitrectomy - without ever having had cataract surgery - will experience progression of nuclear sclerosis at 6-months and 12-month after the operation. This may be because the native vitreous humour contains ascorbic acid which helps neutralize oxidative damage to the lens. Traditional vitreous substitutes such as balanced salt solution do not contain ascorbic acid. As such, for phakic patients requiring a vitrectomy it is becoming increasingly common for ophthalmologists to offer the vitrectomy with a combined prophylactic cataract surgery procedure to prophylactically prevent cataract formation.

Other diseases

• Metabolic and nutrition diseases
  • Aminoaciduria or Lowe's syndrome
  • Diabetes mellitus
  • Fabry's disease
  • Galactosemia / galactosemic cataract
  • Homocystinuria
  • Hyperparathyroidism
  • Hypoparathyroidism
  • Hypervitaminosis D
  • Hypothyroidism
  • Hypocalcaemia
  • Mucopolysaccharidoses
  • Wilson's disease
• Congenital
  • Congenital syphilis
  • Cytomegalic inclusion disease
  • Rubella
  • Cockayne syndrome

• Genetic syndromes
  • Down syndrome
  • Patau syndrome
  • Edwards syndrome
• Infections:
  • Cysticercosis
  • Leprosy
  • Onchocerciasis
  • Toxoplasmosis
  • Varicella
• Secondary to other eye diseases:
  • Retinopathy of prematurity
  • Aniridia
  • Uveitis
  • Retinal detachment
  • Retinitis pigmentosa

A cat with cataracts in both eyes.

Classification

Cross-sectional view, showing the position of the human lens

Cataracts may be partial or complete, stationary or progressive, or hard or soft. The main types of age-related cataracts are nuclear sclerosis, cortical, and posterior subcapsular.

Nuclear sclerosis, the most common type of cataract, involves the central or 'nuclear' part of the lens. Over time, this becomes hard or 'sclerotic' due to condensation of lens nucleus and deposition of brown pigment within the lens. In advanced stages, it is called brunescent cataract. This type of cataract can present with a shift to nearsightedness and causes problems with distance vision, while reading is less affected.

Cortical cataracts are due to the lens cortex (outer layer) becoming opaque. They occur when changes in the water content of the periphery of the lens causes fissuring. When these cataracts are viewed through an ophthalmoscope or other magnification system, the appearance is similar to white spokes of a wheel. Symptoms often include problems with glare and light scatter at night.

Posterior subcapsular cataracts are cloudy at back of the lens adjacent to the capsule (or bag) in which the lens sits. Because light becomes more focused toward the back of the lens, they can cause disproportionate symptoms for their size.

An immature cataract has some transparent protein, but with a mature cataract, all the lens protein is opaque. In a hypermature or Morgagnian cataract, the lens proteins have become liquid. Congenital cataract, which may be detected in adulthood, has a different classification and includes lamellar, polar, and sutural cataracts.

Cataracts can be classified by using the lens opacities classification system LOCS III. In this system, cataracts are classified based on type as nuclear, cortical, or posterior. The cataracts are further classified based on severity on a scale from 1 to 5. The LOCS III system is highly reproducible.

Prevention

Risk factors such as UVB exposure and smoking can be addressed, but are unlikely to make large difference to visual function. Although no means of preventing cataracts has been scientifically proven, wearing ultraviolet-protecting sunglasses may slow the development. While regular intake of antioxidants (such as vitamins A, C, and E) has been thought to protect against the risk of cataracts, clinical trials have shown it does not. Evidence is mixed, but weakly positive, for a potential protective effect of the nutrients lutein and zeaxanthin. Statin use is somewhat associated with a lower risk of nuclear sclerotic cataract.

Treatment

Surgical

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

Slit lamp photo of posterior capsular opacification visible a few months after implantation of intraocular lens in eye, seen on retroillumination

Cataract removal can be performed at any stage and no longer requires ripening of the lens. Surgery is usually 'outpatient' and performed using local anesthesia. About 9 of 10 patients can achieve a corrected vision of 20/40 or better after surgery.

Several recent evaluations found surgery can only meet expectations when significant functional impairment from poor vision exists prior to surgery. Visual function estimates such as VF-14 have been found to give more realistic estimates than visual acuity testing alone. In some developed countries, a trend to overuse cataract surgery has been noted, which may lead to disappointing results.

Phacoemulsification is the most widely used cataract surgery. This procedure uses ultrasonic energy to emulsify the cataract lens. Phacoemulsification typically comprises six steps:

• Anaesthetic - The eye is numbed with either a subtenon injection around the eye or using simple eye drops.
• Corneal incision - Two cuts are made through the clear cornea to allow insertion of instruments into the eye.
• Capsulorhexis - A needle or small pair of forceps is used to create a circular hole in the capsule in which the lens sits.
• Phacoemulsification - A handheld probe is used to break up and emulsify the lens into liquid using the energy of ultrasound waves. The resulting 'emulsion' is sucked away.
• Irrigation and aspiration - The cortex, which is the soft outer layer of the cataract, is aspirated or sucked away. Fluid removed is continually replaced with a saline solution to prevent collapse of the structure of the anterior chamber (the front part of the eye).
• Lens insertion - A plastic, foldable lens is inserted into the capsular bag that formerly contained the natural lens. Some surgeons also inject an antibiotic into the eye to reduce the risk of infection. The final step is to inject salt water into the corneal wounds to cause the area to swell and seal the incision.

Extracapsular cataract extraction (ECCE) consists of removing the lens manually, but leaving the majority of the capsule intact. The lens is expressed through a 10– to 12-mm incision which is closed with sutures at the end of surgery. ECCE is less frequently performed than phacoemulsification, but can be useful when dealing with very hard cataracts or other situations where emulsification is problematic. Manual small incision cataract surgery (MSICS) has evolved from ECCE. In MSICS, the lens is removed through a self-sealing scleral tunnel wound in the sclera which, ideally, is watertight and does not require suturing. Although "small", the incision is still markedly larger than the portal in phacoemulsion. This surgery is increasingly popular in the developing world where access to phacoemulsification is still limited.

Intracapsular cataract extraction (ICCE) is rarely performed. The lens and surrounding capsule are removed in one piece through a large incision while pressure is applied to the vitreous membrane. The surgery has a high rate of complications.

Prognosis

Postoperative care

Slit lamp photo of anterior capsular opacification visible a few months after implantation of intraocular lens in eye, magnified view

The postoperative recovery period (after removing the cataract) is usually short. The patient is usually ambulatory on the day of surgery, but is advised to move cautiously and avoid straining or heavy lifting for about a month. The eye is usually patched on the day of surgery and use of an eye shield at night is often suggested for several days after surgery.

In all types of surgery, the cataractous lens is removed and replaced with an artificial lens, known as an intraocular lens, which stays in the eye permanently. Intraocular lenses are usually monofocal, correcting for either distance or near vision. Multifocal lenses may be implanted to improve near and distance vision simultaneously, but these lenses may increase the chance of unsatisfactory vision.

Complications

Serious complications of cataract surgery are retinal detachment and endophthalmitis. In both cases, patients notice a sudden decrease in vision. In endophthalmitis, patients often describe pain. Retinal detachment frequently presents with unilateral visual field defects, blurring of vision, flashes of light, or floating spots.

The risk of retinal detachment was estimated as about 0.4% within 5.5 years, corresponding to a 2.3-fold risk increase compared to naturally expected incidence, with older studies reporting a substantially higher risk. The incidence is increasing over time in a somewhat linear manner, and the risk increase lasts for at least 20 years after the procedure. Particular risk factors are younger age, male sex, longer axial length, and complications during surgery. In the highest risk group of patients, the incidence of pseudophakic retinal detachment may be as high as 20%.

The risk of endophthalmitis occurring after surgery is less than one in 1000.

Corneal oedema and cystoid macular oedema are less serious but more common, and occur because of persistent swelling at the front of the eye in corneal oedema or back of the eye in cystoid macular oedema. They are normally the result of excessive inflammation following surgery, and in both cases, patients may notice blurred, foggy vision. They normally improve with time and with application of anti-inflammatory drops. The risk of either occurring is around one in 100.

Posterior capsular opacification, also known as after-cataract, is a condition in which months or years after successful cataract surgery, vision deteriorates or problems with glare and light scattering recur, usually due to thickening of the back or posterior capsule surrounding the implanted lens, so-called 'posterior lens capsule opacification'. Growth of natural lens cells remaining after the natural lens was removed may be the cause, and the younger the patient, the greater the chance of this occurring. Management involves cutting a small, circular area in the posterior capsule with targeted beams of energy from a laser, called Nd:YAG laser capsulotomy, after the type of laser used. The laser can be aimed very accurately, and the small part of the capsule which is cut falls harmlessly to the bottom of the inside of the eye. This procedure leaves sufficient capsule to hold the lens in place, but removes enough to allow light to pass directly through to the retina. Serious side effects are rare. Posterior capsular opacification is common and occurs following up to one in four operations, but these rates are decreasing following the introduction of modern intraocular lenses together with a better understanding of the causes.

Vitreous touch syndrome is a possible complication of intracapsular cataract extraction.

Epidemiology

Disability-adjusted life year for cataracts per 100,000 inhabitants in 2004:

  no data

  <90

  90–180

  180–270

  270–360

  360–450

  450–540

  540–630

  630–720

  720–810

  810–900

  900–990

  >990

Age-related cataracts are responsible for 51% of world blindness, about 20 million people. Globally, cataracts cause moderate to severe disability in 53.8 million (2004), 52.2 million of whom are in low and middle income countries.

In many countries, surgical services are inadequate, and cataracts remain the leading cause of blindness. Even where surgical services are available, low vision associated with cataracts may still be prevalent as a result of long waits for, and barriers to, surgery, such as cost, lack of information and transportation problems.

In the United States, age-related lens changes have been reported in 42% between the ages of 52 and 64, 60% between the ages 65 and 74, and 91% between the ages of 75 and 85. Cataracts affect nearly 22 million Americans age 40 and older. By age 80, more than half of all Americans have cataracts. Direct medical costs for cataract treatment are estimated at $6.8 billion annually.

In the eastern Mediterranean region, cataracts are responsible for over 51% of blindness. Access to eye care in many countries in this region is limited.

History

See also: Cataract surgery § History

The first references to cataracts and their treatment in Ancient Rome are found in 29 AD in De Medicinae, the work of the Latin encyclopedist Aulus Cornelius Celsus. Archaeological evidence of eye surgery in the Roman era also exists.

Other early accounts are found in Sanskrit. Cataract surgery was described by the Indian physician, Suśruta (about 200 AD).

Muslim ophthalmologist Ammar ibn Ali, in his Choice of Eye Diseases, written circa 1000, wrote of his invention of a syringe and the technique of cataract extraction while experimenting with it on a patient.

Etymology

"Cataract" is derived from the Latin cataracta, meaning "waterfall", and from the Ancient Greek καταρράκτης (katarrhaktēs), "down-rushing", from καταράσσω (katarassō) meaning "to dash down" (from kata-, "down"; arassein, "to strike, dash"). As rapidly running water turns white, so the term may have been used metaphorically to describe the similar appearance of mature ocular opacities. In Latin, cataracta had the alternative meaning "portcullis" and the name possibly passed through French to form the English meaning "eye disease" (early 15th century), on the notion 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.

Research

A South African woman experiences newfound eyesight after a patch was removed after surgery to remove an eye cataract.

N-Acetylcarnosine drops have been investigated as a medical treatment for cataracts. The drops are believed to work by reducing oxidation and glycation damage in the lens, particularly reducing crystallin crosslinking. Some benefit has been shown in small manufacturer sponsored randomized controlled trials but further independent corroboration is still required.

Femtosecond laser mode-locking, used during cataract surgery, was originally used to cut accurate and predictable flaps in LASIK surgery, and has been introduced to cataract surgery. The incision at the junction of the sclera and cornea and the hole in capsule during capsulorhexis, traditionally made with a handheld blade, needle, and forceps, are dependent on skill and experience of the surgeon. Sophisticated three-dimensional images of the eyes can be used to guide lasers to make these incisions. Nd:YAG laser can also then break up the cataract as in phacoemulsification.

References

Bibliography

• Yanoff, Myron; Duker, Jay S. (2008). Ophthalmology (3rd ed.). Edinburgh: Mosby. ISBN 978-0323057516. 

External links

• Pictures of Different types of Cataract s
• Cataract at DMOZ
• Video describing history and science of seeing cataracts in your own eye on YouTube

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

• 1. 成人における白内障 cataract in adults
• 2. ステロイドの全身投与の主な副作用 major side effects of systemic glucocorticoids
• 3. 眼の待機手術に対する麻酔 anesthesia for elective eye surgery
• 4. 小児における白内障 cataract in children
• 5. 白色瞳孔を有する小児に対するアプローチ approach to the child with leukocoria

English Journal

• Determination of the density of human nuclear cataract lenses.

• Xu K, Hao Y.SourceDepartment of Ophthalmology, Peking University Third Hospital, Haidian, Beijing 100191, P.R. China.
• Molecular medicine reports.Mol Med Rep.2013 Nov;8(5):1300-4. doi: 10.3892/mmr.2013.1673. Epub 2013 Sep 9.
• The aim of the present study was to detect senile nuclear cataract lens density and provide a quantitative measurement of lens density for the long-term clinical observation of cataracts. An Anterior Segment Analysis System was used to detect the lens density of 422 simple senile cataract eyes and
• PMID 24026512

• Defining the seriousness of proliferative vitreoretinopathy by aspiration of cytokines from the anterior chamber.

• Rusnak S, Vrzalova J, Hecová L, Kozova M, Topolcan O, Ricarova R.SourceDepartment of Ophthalmology, University Hospital in Pilsen, Alej Svobody 80, Pilsen, 304 60, Czech Republic.
• Biomarkers in medicine.Biomark Med.2013 Oct;7(5):759-67. doi: 10.2217/bmm.13.65.
• Aim: Proliferative vitreoretinopathy is the major cause of retinal detachment surgery failure. Our prospective cohort study of 27 eyes aimed to determine intraocular levels of growth factors and cytokines in patients with retinal detachment with various degrees of severity of proliferative vitreoret
• PMID 24044568

Japanese Journal

• S1-3 Truncations in αA-crystallins : Molecular Basis for Senile Cataract(Symposium 1,The 37^<th> Annual Meeting of the SSOEL-Japan)

• Anbarasu K.,Ramkumar S.,Thankappan Bency,Abraham E.C.
• Viva origino 40(Supplement), 9, 2012-03-01
• NAID 110009470548

• Experiment to Evaluate Visibility with Street Luminaires with Different Upward Light Output Ratios and the Use of Calculated Veiling Luminance to Determine Contrast Performance

• IWATA Michico,UCHIDA Shigemi
• Journal of light and visual environment 35(1), 42-54, 2011-04-01
• NAID 10028106591

• Difference in Redox Status of Serum and Aqueous Humor in Senile Cataract Patients as Monitored via the Albumin Thiol-Redox State

• Kawai Kenji,Hayashi Tomoya,Matsuyama Yukie [他],MINAMI Takeshi,ERA Seiichi
• Japanese journal of ophthalmology 54(6), 584-588, 2010-11-01
• NAID 10027666349

Related Links

• senile cataract - definition of senile cataract in the Medical ...

cataract /cat·a·ract/ (-rakt) an opacity of the crystalline lens of the eye or its capsule.catarac´tous after-cataract a recurrent capsular cataract. atopic cataract cataract in those with long-standing atopic dermatitis. black cataract see senile nuclear sclerotic c.

• Senile Cataract

Dr Tarek Maamoun Eye Center offers the highest quality medical services regarding eye surgery and diseases. Our services include vision correction of myopia, hypermetropia and astigmatism, lasik, optimized lasik , customized ...

Related Pictures

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★リンクテーブル★

リンク元	「加齢白内障」
拡張検索	「foveal hypoplasia and presenile cataract syndrome」
関連記事	「senile」

「加齢白内障」

　　[★]

英

age-related cataract

同

老人性白内障 senile cataract

関

白内障

分類 (SOP.66)

• 皮質白内障：加齢白内障で最も多い。水晶体周辺から楔錠に混濁が存在。
• 核白内障　：近視眼に多い。
• 嚢下白内障：前極/後極を中心に水晶体嚢近くに混濁が存在。

「foveal hypoplasia and presenile cataract syndrome」

　　[★]

参考

• OMIM

http://omim.org/entry/136520

「senile」

　　[★]

• adj.

• 老年性の、老人性の、老年期の、老衰の、老化の

関

ageing、aging、geriatric、senescence、senescent、senility、senium